A turbine bolt tightening apparatus and method

Abstract

The present application relates to the technical field of auxiliary power device assembly, and more particularly to a turbine bolt tightening device and a tightening method, wherein the device comprises a turbine bolt tightening test device and a turbine bolt tightening device; the turbine bolt is tested by the tightening test device; the fitting torque and the tightening angle are determined through the test; and the turbine bolts with the mutual elongation difference meeting the requirements are selected into groups; the selected turbine bolts are assembled by the turbine bolt tightening device according to the determined fitting torque and the tightening angle; the full fitting between the connected parts and between the turbine bolt, the nut end face and the connected part can be realized; and the elongation of the turbine bolt can be controlled to achieve the purpose of controlling the pre-tightening force. The present application can accurately control the elongation, reduce the pre-tightening force dispersion, realize the bolt grouping and selection, and improve the assembly consistency.

Description

Technical Field

[0001] This invention relates to the technical field of auxiliary power unit assembly, and more specifically, to a turbine bolt tightening device and tightening method. Background Technology

[0002] The auxiliary power unit turbine is a single-rotor, two-stage axial-flow turbine. Its function is to convert the thermal energy of the gas into mechanical energy to drive accessories such as centrifugal compressors and alternators. It mainly consists of a turbine shaft, a first-stage turbine disk, a second-stage turbine disk, and turbine bolts. The first-stage turbine disk has three bolt holes, and the disk is connected to the turbine shaft via turbine bolts. The second-stage turbine disk has three bolt holes at the same angular position as the first-stage turbine disk. The second-stage turbine disk and the first-stage turbine disk are fitted together with an interference fit using a stop, and the first-stage turbine disk, second-stage turbine disk, and turbine shaft are all fastened together with turbine bolts.

[0003] The dynamic performance of aero-engine rotors is significantly affected by the assembly quality of bolted connections. Engineering projects have revealed numerous problems of functional and performance degradation in rotating engine components due to unreliable bolt connection quality, particularly preload degradation under large lateral loads and loosening under high temperature and pressure environments. Uncontrollable bolt connection interface quality and preload degradation lead to unstable bolted joint performance, exhibiting uncertainty with changing external loads. This directly causes changes in the stiffness and damping characteristics of the joint and the overall rotating component structure, while also increasing rotor imbalance, subsequently causing deviations in the dynamic performance of the rotating components and the entire rotor system. Therefore, controlling the turbine bolt preload is particularly crucial.

[0004] Within its elastic range, the elongation of a bolt is directly proportional to the tensile force (preload), following Hooke's Law. Traditional methods (such as the torque method) indirectly obtain preload by controlling the tightening torque. However, most of the torque is used to overcome the friction between the bolt head and the threaded joint, with only a very small portion being converted into the bolt's preload. Even small fluctuations in the coefficient of friction can lead to significant dispersion in the preload.

[0005] In contrast, elongation has a direct physical relationship with preload and is unaffected by the coefficient of friction, thus offering extremely high precision. Directly measuring or controlling bolt elongation is equivalent to directly controlling bolt preload. This method minimizes preload dispersion caused by unstable friction coefficients and tool precision issues, making it one of the most precise bolt preload methods currently available.

[0006] According to the bolt tightening process, due to the existence of fit tolerances and clearances, the relationship between the angle and the preload can only be determined after all mating surfaces are fully engaged. Therefore, whether to directly use the torque method for tightening or to use elongation control requires research on tightening control strategies to better control the preload.

[0007] Aero engines commonly use the torque method for tightening, which is affected by factors such as self-locking torque, friction coefficient, and lubrication conditions. Due to the lack of automated tooling on-site, the torque method is frequently used for tightening, resulting in low precision in preload control. Furthermore, there are no regulations specifying the testing parameters for incoming bolts, making it difficult to identify bolts with poor tightening quality. In addition, the tightening process lacks monitoring methods, making it impossible to identify bolts with excessive preload.

[0008] Existing measurement methods can only measure the static length of tension bolts, but it is difficult to accurately measure the elongation of tension bolts before and after applying torque. The requirement that the tension bolts of the two-stage turbine disc of the 45-80kW auxiliary power unit be grouped according to the difference in elongation before and after applying torque (not greater than 0.01mm) before assembly further increases the difficulty of control.

[0009] For the tensioning bolts of the two-stage turbine disc in auxiliary power units with power ranging from 45 to 80 kW, the existing technology generally has the following technical problems: the elongation is difficult to measure accurately and dynamically; before assembly, the bolts need to be grouped according to the difference in elongation before and after applying torque not exceeding 0.01 mm, which is extremely difficult to control; the determination method of contact torque and angle in the torque-angle method is not precise enough, and there is a lack of monitoring and verification means; the preload is highly discrete and the contact surface is poor, which can easily lead to huge eccentricity and imbalance when the rotor exceeds the critical speed, causing engine rubbing and excessive vibration. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a turbine bolt tightening device and tightening method that can accurately control the elongation, reduce the preload dispersion, realize bolt grouping and matching, and improve assembly consistency.

[0011] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A turbine bolt tightening device is provided, comprising a turbine bolt tightening test device and a turbine bolt tightening device; the turbine bolt tightening test device includes a base, a positioning plate, a sleeve, a mounting base, an ultrasonic preload sensor, an electric tightening tool, a dynamic torque sensor, and a signal acquisition card. The positioning plate and the sleeve are mounted on the top of the base. The positioning plate has a through hole for mounting the electric tightening tool and an observation window for observing the tightening of the nut. The mounting base has a limiting part for circumferentially limiting the head of the turbine bolt with the mounting edge. The sleeve is sleeved on the outer periphery of the turbine bolt, and the end face of the sleeve is flush with the mounting edge of the turbine bolt. The sleeve is in contact with the turbine disc and the axial height of the sleeve is equal to the mating height of the two-stage turbine disc and the turbine bolt. The threaded end of the turbine bolt extends into the through hole. The dynamic torque sensor is connected to the electric tightening tool, and the ultrasonic preload sensor is installed on the mounting base. The dynamic torque sensor and the ultrasonic preload sensor are respectively connected to the signal acquisition card. The turbine bolt tightening device includes a base, a spline sleeve, and a wrench head. The base is fixed on the worktable. The spline sleeve is fixedly connected to the base by fasteners. The spline sleeve has an internal spline that mates with the external spline of the turbine shaft. One end of the wrench head mates with the head of the turbine bolt, and the other end of the wrench head mates with a torque wrench.

[0012] In this invention, the turbine bolt tightening device is used by placing the base horizontally, with the positioning plate and sleeve mounted on top of the base. The turbine bolt to be tested passes through the mounting base and sleeve, with the threaded end of the turbine bolt extending into the through hole and the head located at the limiting part. This ensures that the turbine bolt rotates synchronously with the mounting base, guaranteeing effective torque transmission when needed. An electric tightening tool is used to tighten the nut in the through hole, and the tightening status is observed through an observation window. Torque and rotation angle signals are acquired by a dynamic torque sensor, and elongation and preload signals are collected by an ultrasonic preload sensor. The two signals are then analyzed. The signal enters the signal acquisition card, calculates the contact torque and tightening angle, and selects three turbine bolts with mutually satisfying elongation differences as a group. The base is fixed to the worktable, and the spline sleeve is fixedly connected to the base. The two-stage turbine disk and turbine shaft are flipped and installed onto the spline sleeve and base, ensuring a good fit between the outer spline of the turbine shaft and the inner spline of the spline sleeve to prevent axial rotation. The three selected turbine bolts are passed through the two-stage turbine disk, nuts are tightened, and the bolts are tightened using a torque wrench and wrench head according to the contact torque and tightening angle until the elongation of all three turbine bolts simultaneously meets the requirements, completing the turbine bolt tightening. In this invention, elongation and preload are dynamically monitored in real time during the tightening process, allowing for precise control of elongation, reducing preload dispersion, enabling bolt grouping and matching, and improving assembly consistency. This invention is applicable to the testing, selection, and assembly of turbine bolts for two-stage turbine disks in 45-80kW auxiliary power units.

[0013] Furthermore, the top of the base is provided with a first bracket, a second bracket, and a third bracket in sequence. The positioning plate is positioned and installed on the first bracket. The two ends of the sleeve are respectively supported by the second bracket and the third bracket, and the mounting base is supported by the third bracket.

[0014] Furthermore, the first bracket has a centering hole, the positioning disk includes a positioning disk body, one side of the positioning disk body has a protruding ring, the other side of the positioning disk body has a centering shaft, the protruding ring cooperates with the centering hole, the positioning disk body is attached to and fixedly connected to the first bracket, and the through hole and the observation window are opened on the centering shaft.

[0015] Furthermore, one end of both the second bracket and the third bracket is provided with a V-shaped block and a pressing block, and the inscribed circle diameter of the V-shaped block and the pressing block is consistent with the outer diameter of the sleeve.

[0016] The present invention also provides a method for tightening turbine bolts, applied to the aforementioned turbine bolt tightening equipment; comprising the following steps: S1: The torque-angle method is adopted as the tightening strategy. The turbine bolt tightening test device is used to tighten the turbine bolt under test. First, the torque method is used to apply the contact torque to make the connected parts fit together. Then, the angle method is used to apply the designed angle to achieve the target preload force, and the contact torque and tightening angle of the turbine bolt are obtained. S2: Apply a specified torque to the turbine bolts, and select three turbine bolts whose elongation before and after applying the torque meets the requirements to form a group for assembly; S3: Install the first-stage turbine disk, the second-stage turbine disk, and the turbine shaft onto the turbine bolt tightening device, and secure them with the selected 3 turbine bolts and nuts; S4: Use a wrench head to tighten the three turbine bolts according to the contact torque and tightening angle.

[0017] The turbine bolt tightening method of the present invention involves testing the turbine bolts using a tightening test device to determine the contact torque and tightening angle. Turbine bolts with mutually satisfying elongation differences are then selected and grouped together. The selected turbine bolts are assembled using a turbine bolt tightening device according to the determined contact torque and tightening angle. This method not only achieves full contact between the connected parts and between the turbine bolt and nut end faces and the connected parts, but also controls the elongation of the turbine bolts to control the preload.

[0018] Preferably, in step S1, the process of using the turbine bolt tightening test device to perform a tightening test on the turbine bolt under test includes: S101: Apply a patch to the head of the turbine bolt and calibrate each turbine bolt, then save the bolt calibration file; S102: Based on the measurement principle, install the turbine bolt to be tested, use the distributed tightening method, and use an electric tightening tool to apply tightening torque and rotation angle to the turbine bolt to be tested, and tighten the nut to the target torque; S103: The dynamic input torque during the tightening process is recorded by a dynamic torque sensor, and the preload is obtained by an ultrasonic preload sensor; S104: Based on the test data, plot the rotation angle-torque tightening curves for each group of turbine bolts and nuts during the tightening process; S105: Calculate the contact torque of multiple sets of turbine bolts and nuts using linear fitting or differentiation methods, and take the average value as the contact torque of the turbine bolts in this batch under the torque-angle method. S106: Based on the pre-tightening force, target pre-tightening force and test angle of the tightening test measured in the test, obtain the slope value of the angle-pre-tightening force curve during the tightening process, that is, the angle-pre-tightening force change rate, and determine the tightening angle.

[0019] Preferably, in step S106, the process of determining the tightening angle is as follows: ; ; ; ; In the formula, Indicates the rate of change of angle versus preload; Indicates the target preload; Indicates the preload force for the fit; Indicates the test angle for the tightening test; Indicates the maximum design angle; Indicates the minimum design rotation angle; Indicates the minimum preload for bonding; Indicates the maximum preload force for bonding; This represents the minimum rotation angle versus the rate of change of preload. This represents the maximum rotation angle versus the rate of change of preload. This indicates tightening the corner.

[0020] Preferably, during the tightening test, the monitoring torque is calculated: ; ; In the formula, Indicates the maximum monitored torque; Indicates the minimum monitored torque; Indicates the maximum torque coefficient; Indicates the minimum torque coefficient; Indicates the target preload; This represents the average value of the self-locking torque; Indicates the pitch diameter of the turbine bolt; If the final torque of the torque-angle tightening process exceeds the monitored torque range, the turbine bolts need to be retightened until the monitored torque range requirement is met.

[0021] Preferably, the dispersion of the torque-angle method is set to determine the maximum and minimum values ​​of the preload during the angle stage, and the final installation preload range is calculated: ; ; In the formula, This indicates the dispersion of the torque-angle method; This indicates the maximum installation preload of the turbine bolts after verification using the torque-angle method; This indicates the minimum installation preload of the turbine bolt after verification using the torque-angle method; Indicates the maximum preload force for bonding; Indicates the minimum preload for bonding; Indicates tightening the corner; This represents the minimum rotation angle versus the rate of change of preload. This represents the maximum rotation angle versus the rate of change of preload. If the minimum installation preload is greater than the design preload, and the maximum installation preload does not exceed the bolt's allowable installation preload, the check is passed; if the minimum installation preload is less than the design preload, the threaded fastener selection must be repeated.

[0022] Preferably, in step S4, the tightening process includes: using a dial indicator stand and a dial indicator head, pressing it against the bottom end face of the worm gear bolt with the nut on the side without applying torque, zeroing the dial indicator and recording the initial position; tightening with a wrench head according to the contact torque and tightening angle, observing the change in the dial indicator reading until the elongation of the worm gear bolt meets the requirements.

[0023] Compared with the prior art, the beneficial effects of this invention are: it can achieve full fit between the connected parts and between the end faces of the turbine bolts and nuts and the connected parts, and can also control the elongation of the turbine bolts to achieve the purpose of controlling the preload. It can accurately control the elongation, reduce the dispersion of the preload, realize the grouping and matching of bolts and improve the assembly consistency. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the turbine bolt tightening test device in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the first support in an embodiment of the present invention; Figure 3This is a schematic diagram of the positioning disk in an embodiment of the present invention; Figure 4 This is a schematic diagram of the mounting base in an embodiment of the present invention; Figure 5 This is a schematic diagram of the turbine bolt tightening device in use according to an embodiment of the present invention; Figure 6 This is a rotation angle-torque tightening curve diagram of the turbine bolt and nut during the tightening process in an embodiment of the present invention.

[0025] In the attached diagram: 1-base; 11-first bracket; 111-centering hole; 12-second bracket; 13-third bracket; 2-positioning plate; 21-positioning plate body; 22-convex ring; 23-centering shaft; 231-through hole; 232-observation window; 3-sleeve; 4-mounting base; 41-limiting part; 5-base; 6-spline sleeve; 7-wrench head; 8-first-stage turbine disk; 9-second-stage turbine disk; 10-turbine shaft. Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments. The accompanying drawings are for illustrative purposes only, representing schematic diagrams rather than actual physical objects, and should not be construed as limiting the scope of this patent. To better illustrate the embodiments of the present invention, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0027] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0028] Example 1 A turbine bolt tightening device, such as Figure 1 , Figure 3 and Figure 5As shown, the device includes a turbine bolt tightening test apparatus and a turbine bolt tightening device. The turbine bolt tightening test apparatus includes a base 1, a positioning plate 2, a sleeve 3, a mounting base 4, an ultrasonic preload sensor, an electric tightening tool, a dynamic torque sensor, and a signal acquisition card. The positioning plate 2 and the sleeve 3 are mounted on the top of the base 1. The positioning plate 2 has a through hole 231 for mounting the electric tightening tool and an observation window 232 for observing the tightening of the nut. The mounting base 4 has a limiting part 41 for circumferentially limiting the head of the turbine bolt with the mounting edge. The sleeve 3 is sleeved on the outer circumference of the turbine bolt, and the end face of the sleeve 3 contacts the mounting edge of the turbine bolt. The axial height of 3 is equal to the mating height of the two-stage turbine disk and the turbine bolt. The threaded end of the turbine bolt extends into the through hole 231. The dynamic torque sensor is connected to the electric tightening tool, and the ultrasonic preload sensor is installed on the mounting base 4. The dynamic torque sensor and the ultrasonic preload sensor are respectively connected to the signal acquisition card. The turbine bolt tightening device includes a base 5, a spline sleeve 6 and a wrench head 7. The base 5 is fixed on the worktable. The spline sleeve 6 is fixedly connected to the base 5 by fasteners. The spline sleeve 6 is provided with an internal spline that mates with the external spline of the turbine shaft 10. One end of the wrench head 7 mates with the head of the turbine bolt, and the other end of the wrench head 7 mates with the torque wrench.

[0029] In use, the aforementioned turbine bolt tightening device involves placing the base 1 horizontally, mounting the positioning plate 2 on top of the base 1 via the sleeve 3, and passing the turbine bolt to be tested through the mounting base 4 and the sleeve 3. The threaded end of the turbine bolt extends into the through hole 231, with the head located at the limiting part 41, ensuring that the turbine bolt rotates synchronously with the mounting base 4, guaranteeing effective torque transmission when needed. An electric tightening tool is used to tighten the nut in the through hole 231, and the tightening status is observed through the observation window 232. Torque and rotation angle signals are acquired through a dynamic torque sensor, and elongation and preload signals are collected through an ultrasonic preload sensor. The two signals are then analyzed. The signal acquisition card is used to calculate the contact torque and tightening angle, and three turbine bolts with mutually satisfying elongation differences are selected as a group. The base 5 is fixed to the worktable, and the spline sleeve 6 is fixedly connected to the base 5. The two-stage turbine disks and turbine shaft 10 are flipped and installed onto the spline sleeve 6 and base 5, ensuring a good fit between the external spline of the turbine shaft 10 and the internal spline of the spline sleeve 6 to prevent axial rotation. The three selected turbine bolts are passed through the first-stage turbine disk 8 and the second-stage turbine disk 9, and nuts are tightened. A torque wrench and wrench head 7 are used to tighten the bolts according to the contact torque and tightening angle until the elongation of all three turbine bolts simultaneously meets the requirements, completing the tightening of the turbine bolts. In this embodiment, the elongation and preload are dynamically monitored in real time during the tightening process, which can accurately control the elongation, reduce the preload dispersion, achieve bolt grouping and matching, and improve assembly consistency. This method is applicable to the testing, selection, and assembly of turbine bolts for two-stage turbine disks in 45-80kW auxiliary power units.

[0030] The limiting part 41 has an opening on one side, and the dimension of the opening along the axial direction of the mounting base 4 is greater than the thickness of the turbine bolt head, so as to facilitate adjustment and ensure full contact of the mating parts. The inner cavity shape of the limiting part 41 matches the head of the turbine bolt, so that the turbine bolt can be synchronized with the mounting base 4 when rotating in the circumferential direction, and ensure that torque can be effectively transmitted when needed.

[0031] like Figure 4 As shown, mounting base 4 has a squirrel cage structure, which allows for easy observation of the working status of the turbine bolt under test and the ultrasonic preload sensor.

[0032] like Figure 1 As shown, the top of the base 1 is provided with a first bracket 11, a second bracket 12 and a third bracket 13 in sequence. The positioning plate 2 is positioned and installed on the first bracket 11. The two ends of the sleeve 3 are supported on the second bracket 12 and the third bracket 13 respectively. The mounting base 4 is supported on the third bracket 13.

[0033] like Figure 2 , Figure 3 As shown, the first bracket 11 has a centering hole 111, and the positioning disk 2 includes a positioning disk body 21. A protruding ring 22 is provided on one side of the positioning disk body 21, and a centering shaft 23 is provided on the other side. The protruding ring 22 engages with the centering hole 111, and the positioning disk body 21 is fitted and fixedly connected to the first bracket 11. A through hole 231 and an observation window 232 are provided on the centering shaft 23. Specifically, by engaging the protruding ring 22 with the centering hole 111 and fitting the positioning disk body 21 against the first bracket 11, a centering effect is achieved. The positioning disk body 21 and the first bracket 11 have several corresponding connecting holes. Screws are used to tighten the positioning disk body 21 at the connecting holes to fix the positioning disk 2.

[0034] Both the second bracket 12 and the third bracket 13 have a V-shaped block and a clamping block at one end, and the inner diameter of the V-shaped block and the clamping block is the same as the outer diameter of the sleeve 3. The sleeve 3 can be supported by the V-shaped block, and the sleeve 3 can be fixed by the clamping block in conjunction with the V-shaped block.

[0035] The base 5 has slots on both sides, which can be used to fix the base 5 to the workbench. When installing the spline sleeve 6 onto the base 5, it can be tightened with hexagonal head bolts.

[0036] Each turbine bolt tightening device has three wrench heads 7, and the three wrench heads 7 are at different heights to avoid interference when torque is applied.

[0037] Example 2 A method for tightening turbine bolts, applied to the turbine bolt tightening equipment of Embodiment 1, includes the following steps: S1: The torque-angle method is adopted as the tightening strategy. The turbine bolt tightening test device is used to tighten the turbine bolt under test. First, the torque method is used to apply the contact torque to make the connected parts fit together. Then, the angle method is used to apply the designed angle to achieve the target preload force, and the contact torque and tightening angle of the turbine bolt are obtained. S2: Apply a specified torque to the turbine bolts, and select three turbine bolts whose elongation before and after applying the torque meets the requirements to form a group for assembly; S3: Install the first-stage turbine disk 8, the second-stage turbine disk 9 and the turbine shaft 10 to the turbine bolt tightening device, and fix them with the selected 3 turbine bolts and nuts; S4: Use wrench head 7 to tighten the three turbine bolts according to the contact torque and tightening angle.

[0038] The aforementioned turbine bolt tightening method involves testing the turbine bolts using a tightening test device to determine the contact torque and tightening angle. Turbine bolts with acceptable elongation differences are then grouped together. The selected turbine bolts are assembled using a turbine bolt tightening device according to the determined contact torque and tightening angle. This method ensures a thorough fit between the connected components and between the turbine bolt / nut end faces and the connected components. Furthermore, it allows for control of the turbine bolt elongation to regulate the preload. This embodiment ensures assembly efficiency, enhances assembly stability, reduces assembly difficulty, and effectively avoids situations where poor turbine bolt selection due to preload dispersion leads to excessive vibration values ​​in the entire machine.

[0039] In step S4, the tightening process includes: using a dial indicator stand and a dial indicator head, pressing it against the bottom end face of the worm gear bolt with the nut on the side without applying torque, zeroing the dial indicator and recording the initial position; tightening with the wrench head 7 according to the contact torque and tightening angle, observing the change in the dial indicator reading until the elongation of the worm gear bolt meets the requirements.

[0040] Example 3 This embodiment is similar to Embodiment 2, except that in step S1, the process of using the turbine bolt tightening test device to perform a tightening test on the turbine bolt under test includes: S101: Apply a patch to the head of the turbine bolt and calibrate each turbine bolt, then save the bolt calibration file; S102: Based on the measurement principle, install the turbine bolt to be tested, use the distributed tightening method, and use an electric tightening tool to apply tightening torque and rotation angle to the turbine bolt to be tested, and tighten the nut to the target torque; S103: The dynamic input torque during the tightening process is recorded by a dynamic torque sensor, and the preload is obtained by an ultrasonic preload sensor; S104: Based on the test data, plot the rotation angle-torque tightening curves for each group of turbine bolts and nuts during the tightening process, such as... Figure 6 As shown; S105: Calculate the contact torque of multiple sets of turbine bolts and nuts using linear fitting or differentiation methods, and take the average value as the contact torque of the turbine bolts in this batch under the torque-angle method. S106: Based on the pre-tightening force, target pre-tightening force and test angle of the tightening test measured in the test, obtain the slope value of the angle-pre-tightening force curve during the tightening process, that is, the angle-pre-tightening force change rate, and determine the tightening angle.

[0041] In step S102, an electric tightening tool is used to apply tightening torque and rotation angle to the turbine bolt. The rotation speed of the electric tightening shaft is 3 rad / min, and grease / oil is applied to the first three threads of the turbine bolt. The target torque for measuring the turbine bolt contact torque is 22 Nm. The distributed tightening method involves using an electric tightening tool to tighten the nut to the target torque of the torque method. Loosen the nut completely, then tighten it to the target torque using the torque method. This distributed tightening method releases assembly stress twice during assembly, which is beneficial for assembly performance and stability.

[0042] During the tightening of turbine bolts, contact is a process variable, and a certain amount of time is required from the contact torque to the point of complete contact. Based on the angle-torque tightening curve of the turbine bolt, and according to the change in the curve's slope, the tightening process can be divided into three stages: the initial tightening stage, the contact tightening stage, and the stable tightening stage. The initial stage uses the torque method, the stable stage uses the angle method, and the contact torque needs to be determined in the contact stage. Clearly, the slopes of the curves in the three stages are significantly different. The slope of the curve can be expressed as the ratio of the instantaneous tightening torque to the instantaneous angle.

[0043] If a linear fitting method is used, the characteristic of the turbine bolt's angle-torque tightening curve is that it initially exhibits a nonlinear curve before entering a linear interval. To determine the boundary between the nonlinear and linear intervals, the angle-torque tightening curve can be linearly fitted from back to front, with slope change thresholds set at 0.01% and 3%, respectively. When the slope change after linear fitting exceeds the set threshold, the point is considered to have entered the nonlinear interval, and iteration is stopped. The torque at the point of termination is then taken as the contact torque. By obtaining the slope data of the linear segment of preload, the initial perfect contact point, contact torque, and angle-preload linear segment slope data are obtained.

[0044] When the initial torque is less than the contact torque, the preload dispersion of the torque-angle method for the worm bolt is relatively large. When the initial torque is 50% of the contact torque, the nonlinear segment of the angle-preload curve is relatively large, and the stiffness coefficient of the worm bolt is relatively large. However, when the initial torque is greater than the contact torque, the angle-preload curve of the worm bolt enters the linear segment, the stiffness coefficient of the worm bolt tends to stabilize, and the error of the bolt torque-angle method also tends to stabilize. Therefore, the initial torque of the worm bolt should be greater than the contact torque.

[0045] If the differentiation method is used, in order to find the critical point of each stage, the angle-torque tightening curve is fitted to a polynomial function and its derivative is calculated. The three stages of turbine bolt tightening can be determined according to the slope change of the derivative function.

[0046] In step S106, the process of determining the tightening angle is as follows: ; ; ; ; In the formula, Indicates the rate of change of angle versus preload; Indicates the target preload; Indicates the preload force for the fit; Indicates the test angle for the tightening test; Indicates the maximum design angle; Indicates the minimum design rotation angle; Indicates the minimum preload for bonding; Indicates the maximum preload force for bonding; This represents the minimum rotation angle versus the rate of change of preload. This represents the maximum rotation angle versus the rate of change of preload. This indicates tightening the corner.

[0047] During the tightening test, the monitoring torque is calculated: ; ; In the formula, Indicates the maximum monitored torque; Indicates the minimum monitored torque; Indicates the maximum torque coefficient; Indicates the minimum torque coefficient; Indicates the target preload; This represents the average value of the self-locking torque; Indicates the pitch diameter of the turbine bolt; If the final torque of the torque-angle tightening process exceeds the monitored torque range, the turbine bolts need to be retightened until the monitored torque range requirement is met.

[0048] By setting the dispersion of the torque-angle method, determining the maximum and minimum values ​​of the preload during the angle phase, and calculating the final installation preload range: ; ; In the formula, This indicates the dispersion of the torque-angle method; This indicates the maximum installation preload of the turbine bolts after verification using the torque-angle method; This indicates the minimum installation preload of the turbine bolt after verification using the torque-angle method; Indicates the maximum preload force for bonding; Indicates the minimum preload for bonding; Indicates tightening the corner; This represents the minimum rotation angle versus the rate of change of preload. This represents the maximum rotation angle versus the rate of change of preload. If the minimum installation preload is greater than the design preload, and the maximum installation preload does not exceed the bolt's allowable installation preload, the check is passed; if the minimum installation preload is less than the design preload, the threaded fastener selection must be repeated.

[0049] In the specific implementation of the above embodiments, the technical features can be combined in any non-contradictory way. For the sake of brevity, not all possible combinations of the above technical features are described. However, as long as the combination of these technical features is not contradictory, it should be considered to be within the scope of this specification.

[0050] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A turbine bolt tightening device, characterized in that, Includes a turbine bolt tightening test device and a turbine bolt tightening device; The turbine bolt tightening test device includes a base (1), a positioning plate (2), a sleeve (3), a mounting base (4), an ultrasonic preload sensor, an electric tightening tool, a dynamic torque sensor, and a signal acquisition card. The positioning plate (2) and the sleeve (3) are mounted on the top of the base (1). The positioning plate (2) has a through hole (231) for mounting the electric tightening tool and an observation window (232) for observing the tightening of the nut. The mounting base (4) is provided with a circumferential limit for the head of the turbine bolt with the mounting edge. The limiting part (41) is sleeved on the outer periphery of the turbine bolt. The end face of the sleeve (3) contacts the mounting edge of the turbine bolt, and the axial height of the sleeve (3) is equal to the mating height of the two-stage turbine disk and the turbine bolt. The threaded end of the turbine bolt extends into the through hole (231). The dynamic torque sensor is connected to the electric tightening tool, and the ultrasonic preload sensor is installed on the mounting base (4). The dynamic torque sensor and the ultrasonic preload sensor are respectively connected to the signal acquisition card for communication. The turbine bolt tightening device includes a base (5), a spline sleeve (6), and a wrench head (7). The base (5) is fixed on the workbench. The spline sleeve (6) is fixedly connected to the base (5) by fasteners. The spline sleeve (6) is provided with an internal spline that mates with the external spline of the turbine shaft (10). One end of the wrench head (7) mates with the head of the turbine bolt, and the other end of the wrench head (7) mates with a torque wrench.

2. The turbine bolt tightening device according to claim 1, characterized in that, The base (1) is provided with a first bracket (11), a second bracket (12) and a third bracket (13) in sequence on the top. The positioning plate (2) is positioned and installed on the first bracket (11). The two ends of the sleeve (3) are supported on the second bracket (12) and the third bracket (13) respectively. The mounting base (4) is supported on the third bracket (13).

3. The turbine bolt tightening device according to claim 2, characterized in that, The first bracket (11) has a centering hole (111). The positioning disk (2) includes a positioning disk body (21). A protruding ring (22) is provided on one side of the positioning disk body (21), and a centering shaft (23) is provided on the other side of the positioning disk body (21). The protruding ring (22) cooperates with the centering hole (111). The positioning disk body (21) is attached to and fixedly connected to the first bracket (11). The through hole (231) and the observation window (232) are opened on the centering shaft (23).

4. The turbine bolt tightening device according to claim 2, characterized in that, The second bracket (12) and the third bracket (13) are each provided with a V-shaped block and a pressing block at one end. The inscribed circle diameter of the V-shaped block and the pressing block is consistent with the outer diameter of the sleeve (3).

5. A method for tightening turbine bolts, applied to the turbine bolt tightening equipment according to any one of claims 1 to 4; characterized in that, Includes the following steps: S1: The torque-angle method is adopted as the tightening strategy. The turbine bolt tightening test device is used to tighten the turbine bolt under test. First, the torque method is used to apply the contact torque to make the connected parts fit together. Then, the angle method is used to apply the designed angle to achieve the target preload force, and the contact torque and tightening angle of the turbine bolt are obtained. S2: Apply a specified torque to the turbine bolts, and select three turbine bolts whose elongation before and after applying the torque meets the requirements to form a group for assembly; S3: Install the first-stage turbine disk (8), the second-stage turbine disk (9) and the turbine shaft (10) onto the turbine bolt tightening device, and fix them with the selected 3 turbine bolts and nuts; S4: Use the wrench head (7) to tighten the three turbine bolts according to the contact torque and tightening angle.

6. The turbine bolt tightening method according to claim 5, characterized in that, Step S1, the process of using the turbine bolt tightening test device to perform a tightening test on the turbine bolt under test includes: S101: Apply a patch to the head of the turbine bolt and calibrate each turbine bolt, then save the bolt calibration file; S102: Based on the measurement principle, install the turbine bolt to be tested, use the distributed tightening method, and use an electric tightening tool to apply tightening torque and rotation angle to the turbine bolt to be tested, and tighten the nut to the target torque; S103: The dynamic input torque during the tightening process is recorded by a dynamic torque sensor, and the preload is obtained by an ultrasonic preload sensor; S104: Based on the test data, plot the rotation angle-torque tightening curves for each group of turbine bolts and nuts during the tightening process; S105: Calculate the contact torque of multiple sets of turbine bolts and nuts using linear fitting or differentiation methods, and take the average value as the contact torque of the turbine bolts in this batch under the torque-angle method. S106: Based on the pre-tightening force, target pre-tightening force and test angle of the tightening test measured in the test, obtain the slope value of the angle-pre-tightening force curve during the tightening process, that is, the angle-pre-tightening force change rate, and determine the tightening angle.

7. The turbine bolt tightening method according to claim 6, characterized in that, In step S106, the process of determining the tightening angle is as follows: ； ； ； ； In the formula, Indicates the rate of change of angle versus preload; Indicates the target preload; Indicates the preload force for the fit; Indicates the test angle for the tightening test; Indicates the maximum design angle; Indicates the minimum design rotation angle; Indicates the minimum preload for bonding; Indicates the maximum preload force for bonding; This represents the minimum rotation angle versus the rate of change of preload. This represents the maximum rotation angle versus the rate of change of preload. This indicates tightening the corner.

8. The turbine bolt tightening method according to claim 7, characterized in that, During the tightening test, the monitoring torque is calculated: ； ； In the formula, Indicates the maximum monitored torque; Indicates the minimum monitored torque; Indicates the maximum torque coefficient; Indicates the minimum torque coefficient; Indicates the target preload; This represents the average value of the self-locking torque; Indicates the pitch diameter of the turbine bolt; If the final torque of the torque-angle tightening process exceeds the monitored torque range, the turbine bolts need to be retightened until the monitored torque range requirement is met.

9. The method for tightening turbine bolts according to claim 8, characterized in that, By setting the dispersion of the torque-angle method, determining the maximum and minimum values ​​of the preload during the angle phase, and calculating the final installation preload range: ； ； In the formula, This indicates the dispersion of the torque-angle method; This indicates the maximum installation preload of the turbine bolts after verification using the torque-angle method; This indicates the minimum installation preload of the turbine bolt after verification using the torque-angle method; Indicates the maximum preload force for bonding; Indicates the minimum preload for bonding; Indicates tightening the corner; This represents the minimum rotation angle versus the rate of change of preload. This represents the maximum rotation angle versus the rate of change of preload. If the minimum installation preload is greater than the design preload, and the maximum installation preload does not exceed the bolt's allowable installation preload, the check is passed; if the minimum installation preload is less than the design preload, the threaded fastener selection must be repeated.

10. The method for tightening turbine bolts according to any one of claims 5 to 9, characterized in that, In step S4, the tightening process includes: using a dial indicator stand and a dial indicator head, pressing on the bottom end face of the turbine bolt with the nut on the side without applying torque, setting the dial indicator to zero, and recording the initial position; tightening with a wrench head (7) according to the contact torque and tightening angle, observing the change in the dial indicator reading until the elongation of the turbine bolt meets the requirements.

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