LU504608B1 - A method for determining the tightness of high-strength bolts in wind turbines - Google Patents

Abstract

The invention discloses a wind turbine high strength bolt tightening determination method, comprising step one, selecting a number of wind turbines as judgment examples; step two, extracting judgment examples to set self-reaction washers; step three, obtaining the change trend of bolt preload force and loosening in real time; step four, setting batches and increasing the number of judgment examples per batch; step five, selecting the optimal tightening method as the tightening method for the unit ; by verifying the degree of tightening of bolts by different methods in the same unit, the optimal method is selected to ensure reliability and accuracy in the process of bolt tightening.

Description

A method for determining the tightness of high-strength bolts in wind turbiné$/°04608

TECHNICAL FIELD

The present invention relates to the technical field of wind turbines and more specifically to a method for determining the tightness of high strength bolts in wind turbines.

BACKGROUND

In recent years, high strength bolt breakage has occurred from time to time, seriously affecting the safe operation of wind turbines; in addition, if the tower barrel high strength bolt loosens or breaks, it will lead to increased vibration of the tower barrel and even cause collapse of the tower accident;

At present, the problems in the use of high-strength bolts in wind turbines are: due to the irregular use of high-strength bolt calibration tools, torque spanners are not calibrated before use or unqualified torque spanners are used, which can lead to uncertainty in the overhaul process and overhaul quality; during the calibration process of high-strength bolts, the responsibility, technical ability and even physical strength of the overhaul personnel are all decisive factors in the quality of the calibration; in the actual on-site In the actual maintenance work on site, there have been cases where the maintenance personnel lowered the bolt calibration torque without permission, resulting in poor maintenance of the bolts; the calibration time of high-strength bolts follows the regular maintenance cycle; over-maintenance and under-maintenance of high-strength bolts are hidden dangers for the safe operation of wind turbines; over-maintenance of high-strength bolts will lead to metal fatigue, affecting the service life of the bolts, resulting in fracture, plastic deformation, failure and other consequences Under-maintenance will lead to a reduction in the friction of the connection, resulting in a weakening of the preload and loosening;

Since the location of wind turbines varies and the use of the same fastening method can be affected by temperature and other factors, it is a technical problem to be solved in the art to provide a method of determining which fastening method is used in wind turbines so that they do not break.

SUMMARY

To solve the above problems, the present invention provides the following technical solutions:

A method for determining the tightness of high-strength bolts for wind turbines, comprising abolt, a nut and a hydraulic machine, the threaded end of said bolt being threaded through a flange to said nut:

Step 1, a number of wind turbines of the same type and in a similar location and operating condition are selected as examples for determination;

Step 2, taking any number of judgment cases and providing them with self-reaction washek$/504608 at said bolt-nut connection; for those judgment cases in which said self-reaction washers are equally fitted, the tightness is determined using the yield limit control method and the torque - angle control method respectively; for those judgment cases in which said self-reaction washers are not fitted, the tightness is determined using the torque control method,

Step 3, detecting in real time the tightening data during the tightening process by means of said detection device and analysing said tightening data to obtain trends in the preload force and looseness of the bolts;

Step 4, set batches, increase the number of determination cases per batch and repeat steps 2 to 3;

Step 5, summarise the fastening data of all batches, compare the fastening data of the three fastening methods and select the best fastening method as the fastening method for the unit.

Preferably, in the above method of determining the tightness of a high strength bolt for a wind turbine, said self-reaction washer includes:

A main body, said main body being of cylindrical construction with a circular hole opened in its centre; said main body having a smooth surface

A centring screw ring, which is provided on the inner wall of said circular hole; said centring screw ring has threads on the inner wall matching said bolt for connecting said body to said bolt by means of threads

Guiding teeth, which are provided uniformly on the outer ring of said body;

Knurled striped teeth, which are uniformly provided on the connecting surface of said body and said flange, for increasing the friction between said body and said flange.

Preferably, in the above-mentioned method for determining the tightness of a high strength bolt for a wind turbine, said hydraulic machine tool includes:

Oil pumps, which are used to provide kinetic energy for the fastening process;

A hydraulic spanner, which is connected to the output of said oil pump for converting kinetic energy into mechanical energy;

Transmission member, which is connected to said hydraulic spanner; for carrying out tightening operations on said bolts;

Said drive sleeve, the top of which is fixedly attached to said hydraulic spanner, and the bottom of which is provided with teeth capable of engaging with said guide teeth.

Preferably, in a wind turbine high strength bolt tightness determination method as describéd/504608 above, said detection device includes:

A torque detection component, which is provided on said oil pump for detecting in real time the difference in torque of said bolts;

A corner detection component, which is provided on said oil pump for detecting in real time the difference in twist angle of said bolt;

Ultrasonic elongation meters, which calculate elongation by measuring the difference in sound time of flight between the ultrasonic longitudinal wave in the fastener in its free and fastened state, and derive the fastener preload,

The digital micrometer, which calculates the deformation of the bolt by measuring the effective length of the bolt in the free and tightened state respectively, generates the loosening of the bolt according to the deformation variables.

Preferably, in the above method of determining the tightness of a high strength bolt for a wind turbine, said process of tightening said bolt using the yield limit control method includes:

Step 1, engagement of said drive sleeve's snap teeth with said body's guide teeth;

Step 2, activating said oil pump, driving said drive member to drive said nut to rotate positively on said bolt, tightening said bolt;

Step 3, when a reaction force is generated, said hydraulic spanner is forced to rotate in reverse, driving said drive sleeve to rotate in reverse; as said drive sleeve is engaged and connected to said self-reaction washer, this in turn drives said self-reaction washer to rotate in reverse; as said self- reaction washer is threaded to said bolt, this causes said self-reaction washer to squeeze said flange, increasing the distance between said nut and said flange; ;

Step 4, taking the difference in torque of said bolts and the difference in torsion angle during tightening and calculating the tightening gradient and its yield limit value;

Step 5, when the tightening gradient drops to the yield limit value, said oil pump is braked, tightening is stopped and its preload and looseness are continuously obtained by means of said ultrasonic length gauge and said digital micrometer.

Preferably, in the above method of determining the tightness of a high strength bolt for a wind turbine, said tightness gradient isAM / Ag » WhereinAM denotes the difference in torque of said bolts, andA6 denotes the difference in torsional angle of said bolt

The stated yield limit value isAM / Ag 50% of the maximum value (the maximum tightening gradient in the elastic deformation phase) determined by the straight line segment.

Preferably, in a wind turbine high strength bolt tightening determination method as described above, said process of tightening operation of said bolts by said torque-turn angle control method includes:

Step 1, engaging said drive sleeve's snap teeth with said body's guide teeth to obtain the current preload force to be achieved for the fastener by means of the bolt's specifications;

Step 2, activating said oil pump to drive said drive member to drive said nut on said bolt to turn a pre-set threshold torque;

Step 3, after turning to the threshold torque, add a specified angle of rotation to bring it to preload;

Step 4, the preload and looseness of which is continuously obtained by means of said ultrasonic length gauge and said digital micrometer.

Preferably, in a wind turbine high strength bolt tightening determination method as described above, said process of tightening operation of said bolt by said torque control method includes:

Step 1, activating said oil pump to drive said drive member to rotate said nut to the current preload of the fastener, depending on the specification of the bolt;

Step 2, the preload and looseness of which is continuously obtained by means of said ultrasonic length gauge and said digital micrometer.

Preferably, in the above-mentioned method for determining the fastening of high-strength bolts in a wind turbine, said aggregating the fastening data of the entire batch, comparing the fastening data of the three fastening methods and selecting the optimal fastening method as the fastening method for the unit includes the steps of:

Step 1, the detected preload data and the looseness are classified according to the fastening method;

Step 2, image plotting the preload force data in each fastening method, determining the trend of said preload force changes and ranking the trends based on the steepness of the changes;

Step 3, determining the loosening of said bolts within a set time in each fastening method and ranking them based on the severity of the loosening;

Step 4, the method with the least change in preload force and the weakest looseness is selected as the fastening method for the unit.

As can be seen from the above technical solutions, the beneficial effect of the present application compared to the prior art is that

1. The wind turbine high-strength bolt tightening determination method provided by thé/504608 present invention ensures reliability and accuracy in the bolt tightening process by verifying the degree of tightness of the bolt in the same unit by different methods and monitoring the loosening after a long time, and selecting the optimal method. 5 2. The invention uses three fastening methods and several batches of tests to enhance the accuracy of the experimental results; 3. In the yield limit control method and torque - angle control method to add self-reaction shims, reduce the tightening process of the bolt and the nut is not the center of the eccentric generated eccentric load, bending moment, can obtain greater than the ordinary torque tightening preload, and will not cause the bolt overload, bolt pull off and so on.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to illustrate more clearly the technical solutions in the examples or prior art of the invention, the following is a brief description of the accompanying drawings which are required for the description of the examples or prior art. It will be obvious that the accompanying drawings in the following description are only examples of the invention and that other accompanying drawings may be obtained by those of ordinary skill in the art without creative effort in accordance with the accompanying drawings provided.

Fig. 1 shows a schematic diagram of the process for determining the tightness of high-strength bolts in wind turbines of the present invention,

Fig. 2 shows a schematic diagram of the structural connection of the method for determining the tightness of high-strength bolts in wind turbines of the present invention;

Where 1, bolt; 2, nut; 3, flange; 4, self-reacting washer; 401, guide tooth; 5, hydraulic machine; 6, transmission component; 7, drive sleeve; 701, snap tooth.

DETAILED DESCRIPTION

The technical solutions in the examples of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the examples of the present invention, and it is clear that the examples described are only a part of the examples of the present invention, and not all of them. Based on the examples in the present invention, all other examples obtained without creative labour by a person of ordinary skill in the art fall within the scope of protection of the present invention. The technical solutions in the examples of the invention will be clearly and completely described below in conjunction with the accompanying drawings in the examples of the invention, and it is clear that the examples described are only a part of the examples of the invention and not all of them. Based on the examples in the preseht/504608 invention, all other examples obtained without creative labour by a person of ordinary skill in the art fall within the scope of protection of the present invention.

In the present invention, the terms "first", "second" and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; the terms "plurality" refers to two or more, unless otherwise expressly limited. The terms "fitted", "connected", "joined", "fixed", etc. are to be understood in a broad sense, for example For example, "connected" may be a fixed connection, a removable connection or a one-piece connection, "connected" may be a direct connection or an indirect connection through an intermediate medium.

For a person of ordinary skill in the art, the specific meaning of the above terms in the context of the present invention may be understood in the light of the specific circumstances.

In the description of the present invention, it is to be understood that the terms "top", "bottom", "left", "right", "front", "rear", etc. indicate orientation or positional relationships based on the accompanying drawings and are intended only to facilitate and simplify the description, "front", "rear", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings and are intended only to facilitate and simplify the description of the invention, not to indicate or imply that the device or unit referred to must have a particular orientation, be constructed and operate in a particular It is not intended to indicate or imply that the device or unit referred to must be constructed and operated in a particular orientation, in a particular orientation, and is therefore not to be construed as a limitation of the invention.

In the description of this specification, the terms "an example", "some examples", "specific examples" and the like are used to describe specific features, structures, materials or characteristics that are described in connection with the example or illustration of implementation. In this specification, the schematic expressions of the above terms do not necessarily refer to the same example or embodiment Furthermore, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more of the example or illustration of implementation.

Example 1

In one example, see Figures 1-3, a method for determining the tightness of high-strength bolts for wind turbines, comprising a bolt 1, a nut 2 and a hydraulic machine 5, the threaded end of the bolt 1 being threaded through a flange 3 to the nut 2:

Step 1, a number of wind turbines of the same type and in a similar location and operating condition are selected as examples for determination;

Step 2, taking any number of judgment cases and providing them with self-reaction washek$/504608 at said bolt-nut connection; for those judgment cases in which said self-reaction washers are equally fitted, the tightness is determined using the yield limit control method and the torque - angle control method respectively; for those judgment cases in which said self-reaction washers are not fitted, the tightness is determined using the torque control method,

Step 3, detecting in real time the tightening data during the tightening process by means of said detection device and analysing said tightening data to obtain trends in the preload force and looseness of the bolts;

Step 4, set batches, increase the number of determination cases per batch and repeat steps 2 to 3;

Step 5, summarise the fastening data of all batches, compare the fastening data of the three fastening methods and select the best fastening method as the fastening method for the unit.

The principle of the above example is that a self-reacting washer 4 is used underneath the conventional nut 2 of the wind turbine high-strength bolt 1, replacing the conventional flat washer; the most suitable fastening method for this unit is found by setting a fixed number of units from a fixed batch as an comparative example.

The beneficial effects of the above examples are: by verifying the degree of tightening of bolts in the same unit by different methods and monitoring the loosening situation after a long time, the optimal method is selected to ensure the reliability and accuracy of the bolt tightening process; by adopting the self-reaction tightening method, the eccentric load and bending moment generated by the uncenteredness of bolt 1 and nut 2 in the tightening process is reduced; in the first and second flange of the wind turbine tower 3 High-strength bolts 1 are tightened using the "yield limit control method" and the "torque-turning angle method" using an oil pump, and the process of tightening bolt 1 is basically unaffected by friction, which is much better than ordinary torque tightening, and can obtain a greater preload than ordinary torque tightening. The whole system is monitored by intelligent tightening and does not cause overloading of bolt 1, bolt 1 pull-off, etc.

Example 2

In one example, see Figures 1-3, a method for determining the tightness of high strength bolts for wind turbines, the self-reaction washer 4 comprising:

Main body with a cylindrical structure with a circular hole opened in its centre; smooth surface of the main body

A centring screw ring, which is provided on the inner wall of the circular hole; the inner wall of the centring screw ring is provided with threads matching the bolt 1 for connecting the body to the bolt 1 by means of threads;

Guiding teeth 401, which are provided uniformly on the outer ring of the body; LU504608 knurled striped teeth, which are uniformly provided on the connection surface of the body and the flange 3 for increasing the friction between the body and the flange 3;

Hydraulic machines 5 include:

Oil pumps, which are used to provide kinetic energy for the fastening process;

Hydraulic spanners, which are connected to the output of an oil pump for converting kinetic energy into mechanical energy;

Transmission part 6, which is connected to the hydraulic spanner; for the tightening operation of the bolt 1;

The drive sleeve 7, the top of which is fixedly attached to the hydraulic spanner, is provided at the bottom with a catch 701 capable of engaging with the guide teeth 401.

In this case, the reaction forces generated by the tightening process of the hydraulic machine 5 are evenly distributed on the knurled surface of the washer in combination with the machine, since the reaction forces are distributed circumferentially and are automatically balanced against each other over the entire circumference, so that no additional reaction arms are required; the outer housing of the special double-layer driver is combined with the outer edge guide teeth 401 of the washer to transmit the reaction forces and the inner hexagonal sleeve to transmit the The nut 2 is stretched axially without the need for any other reaction support; there is no bias load during the tightening of bolt 1 and the bending moment on bolt 1 is greatly reduced.

The beneficial effect of the above example is that the lower end of the hydraulically driven sleeve 7 engages with the guiding teeth 401 of the washer, transferring the reaction force to the teeth of the washer, and the bolt 1 is stretched vertically during tightening without bias load, allowing the accuracy of the preload of the bolt 1 to be controlled between +5% and 10%.

In one example, the detection device includes:

A torque detection component, which is provided on the oil pump for real-time detection of the difference in torque of bolt 1;

Torsion angle detection component, which is provided on the oil pump for real-time detection of the difference in torsion angle of the bolt 1;

Ultrasonic elongation meters, which calculate elongation by measuring the difference in sound time of flight between the ultrasonic longitudinal wave in the fastener in its free and fastened state, and derive the fastener preload,

The digital micrometer, which calculates the deformation of the bolt by measuring the effective length of the bolt in the free and tightened state respectively, generates the loosening of the bolt according to the deformation variables.

Among them, torque detection components and torsion angle detection components for thé/504608 existing technology; which, ultrasonic length measuring instrument for the existing technology means, with longitudinal ultrasonic measurement function, equipment hardware ultrasonic part of high sensitivity weak signal transceiver technology, digital control 50-400V excitation adjustable, 0-80dB gain adjustable, adjustable pulse width, 200M high-speed sampling and digital signal processing technology, with the help of high-performance filtering, echo intelligent capture, identification, tracking and other technologies, can be automated to complete the preload force and temperature of real-time measurement and calculation;

Digital micrometer to measure the effective length of bolt 1 in the free state and fastened state respectively, calculate the deformation of bolt 1, and then calculate the fastener preload according to Hooke's law in reverse;

Wherein the digital micrometer, as a second instrumentation for measuring the preload force of the bolts, has a range of 300 mm - 400 mm and a measurement accuracy of 0.001 mm, adapted to the length of said wind turbine high-strength bolt 1;

The principle of the above example is that the ultrasonic length measuring instrument for testing the preload of the bolt works as follows: the ultrasonic length measuring instrument transmits and receives the ultrasonic pulse electrical signals, measures and calculates the time difference between the transmitted and returned electrical signals; the time difference between the transmitted and received electrical signals is TO when the bolt is in the free state, and the time difference between the transmitted and received electrical signals is T1 when the bolt is in the fastened state, thus Based on the relationship between the time difference between the electrical signal transmission and reception and the deformation of the bolt, the deformation of the bolt is obtained as follows

Al = + {(F1-T0}v 2 , and

Where v is the speed of propagation of the mechanical longitudinal wave in the bolt, and the final preload force of the bolt in its current state can be obtained by the ultrasonic length gauge host based on AL and combined with the bolt calibration database (the database of the correspondence between the preload force F and the deformation AL of bolt 1 under torsion and tension for the same batch of bolts);

Using a digital micrometer to measure the effective length of the bolt in the free state and the tightened state respectively, calculate the deformation of bolt 1 and then calculate the preload according to Hooke's law in reverse:

Fo E-S-AL

L

Where F is the preload force of bolt 1; E is the modulus of elasticity of the bolt material; S 14504608 the cross-sectional area of the bolt; AL is the deformation of bolt 1; and L is the clamping length of the bolt pair.

The beneficial effect of the above example is that the auxiliary hydraulic machine 5 uses the yield limit control method to tighten the bolt 1.

Example 3

In one example, referring to Figures 1-3, a method for determining the tightening of high strength bolts for wind turbines, the process of performing a tightening operation on said bolts using a yield limit control method includes:

Step 1, engagement of the teeth of the drive sleeve with the guide teeth of the body;

Step 2, start the oil pump and drive the drive components to drive the nut on the bolt in a positive rotation to tighten the bolt;

Step 3, when a reaction force is generated, the hydraulic spanner is forced to rotate in reverse, driving the drive sleeve to rotate in reverse; as the drive sleeve is engaged and connected to the self-reaction washer, it in turn drives the self-reaction washer to rotate in reverse; as the self- reaction washer is threaded and connected to the bolt, it makes the self-reaction washer squeeze the flange, increasing the distance between the nut and the flange; and

Step 4, taking the difference in bolt torque and the difference in torsion angle during tightening and calculating the tightening gradient and its yield limit value;

Step 5, when the tightening gradient drops to the yield limit value, the brake oil pump is applied, the tightening is stopped and the preload and loosening is continuously obtained by means of an ultrasonic length gauge and a digital micrometer.

The principle of the above example is that bolt 1 is normally damaged by the cyclically varying amplitude of the stress, rather than being tightened to a higher preload (e.g. 95% of the yield limit); tightening to the yield limit point using the method of this example is not the yield limit point under pure tensile testing, but rather the bolt 1 is reached by the combined effect of torsion and the tension generated during the locking rotation of nut 2 "offset-yield-point", which is slightly lower than the actual 0.2 (the actual yield limit point of the bolt); after the tightening is completed, due to the disappearance of the torsional stress, bolt 1 shows a reduction of about 10-20% in the stress value corresponding to the actual preload force relative to the percentage of yield strength; during the tightening of nut 2 When bolt 1 is in the elastic region, the angle of locking rotation and the curve of torque obtained for nut 2 are similar to the stress-strain curve of the material, showing a linear proportional relationship; the intelligent pump obtains the angle of rotation and the value of output torque in real time and calculates this tightening gradient in real time; in the elastic region, the value is theoretically a constant, but the actual tightening has been under the influence of friction etc. When bolt 1 is tightened to the point of producing a slight plastt&/504608 deformation, the tightening gradient will start to decrease, usually the value drops to 50% of the maximum value determined by the linear section (the maximum tightening gradient in the elastic deformation phase) is considered to reach the yield limit point, the intelligent pump automatically stops tightening, bolt 1 reaches the "yield limit point" under the compound action of tension and torque ", some distance short of the actual yield limit point of bolt 1 in the tensile test condition; in one example, the tightening tightening factor aA can be designed and calculated using 1.0.

The beneficial effect of the above-mentioned example is that the tightening operation of the bolt 1 by means of the yield limit control method of tightening is achieved.

Example 4

In one example, see Figures 1-3, a wind turbine high strength bolt tightening determination method, where the oil pump and the detection device can be combined, preferentially selecting a

Kettec intelligent pump for tightening by the yield limit control method.

The principle of the above-mentioned example is: the use of KETEK intelligent pump (model:

Eco2Touch) for the tightening of the yield limit control method of tightening; the use of self- reaction arm hydraulic machine 5 (model: AVANTI-10) to tighten the wind turbine high-strength bolts, can be achieved to minimize the tightening process of the bolt 1 and the nut 2 is not the center of the resulting bias load, bending moment; when the bolt 1 is tightened to When the bolt 1 is tightened to the point of slight plastic deformation, the tightening gradient starts to decrease and usually the value decreases to 50% of the maximum value determined in a straight line (the maximum tightening gradient in the elastic deformation phase), the yield limit point is considered to be reached and the intelligent pump automatically stops tightening and the bolt 1 reaches the "yield limit point" under the combined action of tension and torque.

The beneficial effect of the above-mentioned example is that there is no need to install a separate detection device on the oil pump, and at the same time the intelligent pump can be used for real-time and rapid analysis and processing.

Example 5

In one example, see Figures 1-3, a method for determining the tightness of high strength bolts for wind turbines, with a tightness gradient of AM / Ag > WhereAM denotes the difference in bolt torque, andA@ denotes the difference in bolt torsion angle;

Yield limit values areÂM / Ag 50% of the maximum value (the maximum tightening gradient in the elastic deformation phase) determined by the straight line segment;

The principle of the above example is that after the bolt 1 has been tightened to the "yield/504608 limit point" by turning the nut 2, the bolt is expected to remain in the elastic zone after the tightening is completed, as the torsional stress disappears and the stress relaxes in the member; if a higher additional force is applied to the bolt, the bolt is still first loaded in the elastic zone, and the bolt is further loaded beyond the the yield limit point of the bolt material itself is immediately plasticised and the axial yield point is further increased (cold work-hardening properties of metallic materials), thus further improving the performance of the bolt1;

Performing the yield limit control method of tightening allows the entire connection system to be monitored. Tightening a group of fasteners to the yield point does not mean tightening each fastener to exactly the same preload, different bolts 1 individual in geometry and material will cause some load dispersion and therefore the angle of rotation when the yield limit is reached will be different; tightening by the method of the present invention is largely unaffected by friction and

It is much more effective than ordinary torque tightening and can also obtain a greater preload than ordinary torque tightening, and the whole system is monitored by intelligent tightening without causing bolt overload or bolt pull-off.

The beneficial effects of the above examples are: smaller bolt sizes are used; the number and diameter of bolts can be reduced; standard high-strength bolts are used for the connection; customised non-standard bolts are no longer required; standard high-strength bolts can be reused; standard high-strength bolts from different manufacturers can be used; the fatigue strength of the connection can be increased; tightening can be carried out in accordance with the requirements of certification bodies and auditing bodies; tightening can be carried out in accordance with directives (ISO; VDI-2862-2 Classification and minimum requirements for bolted joints); documentation of the tightening process enables absolute quality control; can be used in conjunction with existing standard hydraulic spanners.

Example 6

In one example, see Figures 1-3, a method for determining the tightening of high-strength bolts for wind turbines, the process of tightening the bolts by the torque-turn angle control method includes:

Step 1, engaging the teeth of the drive sleeve with the guide teeth of the body to obtain the current preload force to be achieved for the fastener by the specification of the bolt;

Step 2, start the oil pump and drive the drive components to drive the nut on the bolt to turn the preset threshold torque;

Step 3, after turning to the threshold torque, add a specified angle of rotation to bring it to preload;

Step 4, where preload and slack are continuously obtained by means of an ultrasonic lengH#504608 gauge and a digital micrometer;

The process of tightening bolts by the torque-controlled method consists of:

Step 1, start the oil pump and drive the drive component to rotate the nut to the current preload of the fastener according to the specification of the bolt;

Step 2, where preload and slack are continuously obtained by means of an ultrasonic length gauge and a digital micrometer;

The fastening data of the entire batch is aggregated, the fastening data of the three fastening methods are compared and the best fastening method is selected as the fastening method for the unit comprising the following steps:

Step 1, the detected preload data and the looseness are classified according to the fastening method;

Step 2, image plotting the preload force data in each fastening method, determining the trend in preload force variation and ranking the trends based on the steepness of the variation;

Step 3, determining the loosening of the bolts within a set time in each fastening method and ranking them based on the severity of the loosening;

Step 4, selecting the method with a gentle trend in preload force variation and the weakest loosening as the fastening method for the unit;

In one example, three wind turbines of the same model with similar locations and operating conditions were selected for the first batch, and using the Eco2Touch intelligent bolt tightening research-type workstation, AV-5 and AV-10 torque tensioners were selected as hydraulic machines to tighten the bolts using the torque-control method on the first and second flanges of the tower of wind turbine 1; on the first and second flanges of the tower of wind turbine 2 torque - angle control method (including self-reaction washers) on the flange of WTG 2; yield point control method (including self-reaction washers) on the first and second flange of WTG 3; continuous recording of preload force data and loosening;

After 6 months of experimentation on the platform of the first batch of units and after the experiments were verified to be correct, 10 wind turbines of the second batch were selected to use the torque-control method to tighten bolts on the first and second flanges of the towers of 2 wind turbines; the torque-angle control method (including self-reaction washers) was carried out on the first and second flanges of the towers of 4 wind turbines; the yield point (including self-reaction washers) was carried out on the first and second flanges of the towers of 4 wind turbines. controlled method (including self-reflex washers) experiments; continuous recording of preload data and loosening;

After six months of experimentation on the second batch of units, the torque control methdd/504608 was used to tighten bolts on the first and second flanges of the towers of two wind turbines; the torque - angle control method (including self-reaction washers) was carried out on the first and second flanges of the towers of seven wind turbines; and the yield point (including self-reaction washers) was carried out on the first and second flanges of the towers of seven wind turbines. controlled method (including self-reflex washers) experiments; continuous recording of preload force data and loosening;

The experimental data from 29 experimental units in three batches were compiled, and the preload data recorded were analysed to find out the trend of the bolt preload, to compare and study the effectiveness of the three fastening methods in preventing bolt breakage and loosening, and to select the most suitable fastening method as the fastening method for this wind turbine.

The beneficial effect of the above-mentioned examples is that the reasonableness of the determination of the fastening method is improved, the state of the bolts is continuously checked and it is possible to ensure that the final selection of the fastening method best meets the current fastening method of the unit.

It should be noted that the system provided by the above examples is only illustrated by the division of the above-mentioned functional modules. In practice, the above-mentioned functions can be assigned by different functional modules according to the needs, i.e. the modules or steps in the examples of the present invention can be further decomposed or combined, for example, the modules of the above examples can be combined into one module or further divided into several sub-modules, in order to accomplish all or part of the above described functions. to perform all or part of the functions described above. The names of the modules and steps involved in the examples of the present invention are only for the purpose of distinguishing the individual modules or steps and are not to be regarded as unduly limiting the present invention.

The term "includes" or any other similar term 1s intended to cover non-exclusive inclusion such that a process, method, article or equipment/apparatus comprising a range of elements includes not only those elements, but also other elements not expressly listed, or also elements inherent in those processes, methods, articles or equipment/apparatus. The process, method, article or apparatus/apparatus may also include elements that are not explicitly listed or that are inherent to the process, method, article or apparatus/apparatus.

The technical solutions of the invention have thus far been described in connection with the preferred examples shown in the accompanying drawings, but it is readily understood by those skilled in the art that the scope of protection of the invention is clearly not limited to these specific examples. Without departing from the principles of the invention, a person skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technickH504608 solutions after these changes or substitutions will fall within the scope of protection of the invention.

It is clear that a person skilled in the art may make various modifications and variations of the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the invention fall within the scope of the claims of the invention and their technical equivalents, the invention is also intended to include these modifications and variations in the above description of the disclosed examples to enable those skilled in the art to implement or use the invention. Various modifications to these examples will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other examples without departing from the spirit or scope of the invention. Accordingly, the invention will not be limited to these examples shown herein, but will be subject to the widest scope consistent with the principles and novel features disclosed herein.

Claims (9)

CLAIMS LU504608

1. A method for determining the tightness of high strength bolts for wind turbines, characterized in that it comprises a bolt, a nut and a hydraulic machine, the threaded end of said bolt being threaded through a flange to said nut: Step 1, a number of wind turbines of the same type and in a similar location and operating condition are selected as examples for determination; Step 2, taking any number of judgment cases and providing them with self-reaction washers at said bolt-nut connection; for those judgment cases in which said self-reaction washers are equally fitted, the tightness is determined using the yield limit control method and the torque - angle control method respectively; for those judgment cases in which said self-reaction washers are not fitted, the tightness is determined using the torque control method, Step 3, detecting in real time the tightening data during the tightening process by means of said detection device and analysing said tightening data to obtain trends in the preload force and looseness of the bolts; Step 4, set batches, increase the number of determination cases per batch and repeat steps 2 to 3; Step 5, summarise the fastening data of all batches, compare the fastening data of the three fastening methods and select the best fastening method as the fastening method for the unit.

2. The method for determining the tightness of high strength bolts for wind turbines according to claim 1, characterized in that said self-reacting washer comprises: a main body, said main body being of cylindrical construction with a circular hole opened in its centre; said main body having a smooth surface; a centring screw ring, which is provided on the inner wall of said circular hole; said centring screw ring has threads on the inner wall matching said bolt for connecting said body to said bolt by means of threads; guiding teeth, which are provided uniformly on the outer ring of said body; knurled striped teeth, which are uniformly provided on the connecting surface of said body and said flange, for increasing the friction between said body and said flange.

3. The method for determining the tightness of high strength bolts for wind turbines according to claim 2, characterized in that said hydraulic machine comprises: oil pumps, which are used to provide kinetic energy for the fastening process; a hydraulic spanner, which is connected to the output of said oil pump for converting kinetic energy into mechanical energy;

transmission part, which is connected to said hydraulic spanner; for carrying out tightenid&/504608 operations on said bolts; said drive sleeve, the top of which is fixedly attached to said hydraulic spanner, and the bottom of which is provided with teeth capable of engaging with said guide teeth.

4. The method for determining the tightness of high strength bolts for wind turbines according to claim 3, characterized in that said testing device comprises: a torque detection component, which is provided on said oil pump for detecting in real time the difference in torque of said bolts; a corner detection component, which is provided on said oil pump for detecting in real time the difference in twist angle of said bolt; ultrasonic elongation meters, which calculate elongation by measuring the difference in sound time of flight between the ultrasonic longitudinal wave in the fastener in its free and fastened state, and derive the fastener preload, the digital micrometer, which calculates the deformation of the bolt by measuring the effective length of the bolt in the free and tightened state respectively, generates the loosening of the bolt according to the deformation variables.

5. The method for determining the tightening of high strength bolts for wind turbines according to claim 4, characterized in that said process of tightening operation of said bolts using the yield limit control method comprises: Step 1, engagement of said drive sleeve's snap teeth with said body's guide teeth; Step 2, activating said oil pump, driving said drive member to drive said nut to rotate positively on said bolt, tightening said bolt; Step 3, when a reaction force is generated, said hydraulic spanner is forced to rotate in reverse, driving said drive sleeve to rotate in reverse; as said drive sleeve is engaged and connected to said self-reaction washer, this in turn drives said self-reaction washer to rotate in reverse; as said self- reaction washer is threaded to said bolt, this causes said self-reaction washer to squeeze said flange, increasing the distance between said nut and said flange; Step 4, taking the difference in torque of said bolts and the difference in torsion angle during tightening and calculating the tightening gradient and its yield limit value; Step 5, when the tightening gradient drops to the yield limit value, said oil pump is braked, tightening is stopped and its preload and looseness are continuously obtained by means of said ultrasonic length gauge and said digital micrometer.

6. The method for determining the tightness of high strength bolts for wind turbines accordirg/504608 to claim 5, characterized in that said tightness gradient is “Mow wherein a denotes the difference in torque of said bolts, and 88 denotes the difference in torsional angle of said bolt; the stated yield limit value is “8 50% of the maximum value (the maximum tightening gradient in the elastic deformation phase) determined by the straight line segment.

7. The method for determining the tightness of high strength bolts for wind turbines according to claim 6, characterized in that said process of tightening operation of said bolts by said torque- turn angle control method comprises: Step 1, engaging said drive sleeve's snap teeth with said body's guide teeth to obtain the current preload force to be achieved for the fastener by means of the bolt's specifications; Step 2, activating said oil pump to drive said drive member to drive said nut on said bolt to turn a pre-set threshold torque; Step 3, after turning to the threshold torque, add a specified angle of rotation to bring it to preload; Step 4, the preload and looseness of which is continuously obtained by means of said ultrasonic length gauge and said digital micrometer.

8. The method for determining the tightness of high strength bolts for wind turbines according to claim 7, characterized in that said process of tightening operation of said bolts by said torque control method comprises: Step 1, activating said oil pump to drive said drive member to rotate said nut to the current preload of the fastener, depending on the specification of the bolt; Step 2, the preload and looseness of which is continuously obtained by means of said ultrasonic length gauge and said digital micrometer.

9. The method for determining the fastening of high-strength bolts for wind turbines according to claim 8, characterized in that said aggregating the fastening data of the entire batch, comparing the fastening data of the three fastening methods and selecting the optimal fastening method as the fastening method for the unit comprises the steps of: Step 1, the detected preload data and the looseness are classified according to the fastening method; Step 2, image plotting the preload force data in each fastening method, determining the trend of said preload force changes and ranking the trends based on the steepness of the changes; Step 3, determining the loosening of said bolts within a set time in each fastening method and ranking them based on the severity of the loosening;

Step 4, the method with the least change in preload force and the weakest looseness is selected 44504608 the fastening method for the unit.