CN113909800A - Resistance heating control device and method for hot-fastening bolt - Google Patents
Resistance heating control device and method for hot-fastening bolt Download PDFInfo
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- CN113909800A CN113909800A CN202111210125.3A CN202111210125A CN113909800A CN 113909800 A CN113909800 A CN 113909800A CN 202111210125 A CN202111210125 A CN 202111210125A CN 113909800 A CN113909800 A CN 113909800A
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- heating
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P11/00—Connecting or disconnecting metal parts or objects by metal-working techniques not otherwise provided for
- B23P11/02—Connecting or disconnecting metal parts or objects by metal-working techniques not otherwise provided for by first expanding and then shrinking or vice versa, e.g. by using pressure fluids; by making force fits
- B23P11/025—Connecting or disconnecting metal parts or objects by metal-working techniques not otherwise provided for by first expanding and then shrinking or vice versa, e.g. by using pressure fluids; by making force fits by using heat or cold
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P19/00—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes
- B23P19/04—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes for assembling or disassembling parts
- B23P19/06—Screw or nut setting or loosening machines
Abstract
The invention belongs to the field of machinery, and particularly relates to a resistance heating control device and method for a hot-tightening bolt. At present, a resistance heater is mainly adopted in domestic power plants to heat bolts, and problems of undefined control standard, long heating time and the like exist in the heating fastening and dismounting processes, so that screw thread deformation, middle-section steam leakage and even bolt failure are caused, and further the overhaul period is delayed. The device comprises a direct-current electrical cabinet, a resistance heating rod, a temperature monitoring and feedback device, an elongation measuring device, an intelligent control center and a bolt fastening device; the direct current electrical cabinet is connected with a resistance heating rod through a cable, and the resistance heating rod is inserted into a hot-tightening bolt. The invention can effectively shorten the heating time and reduce the failure rate of the bolt.
Description
Technical Field
The invention belongs to the field of machinery, and particularly relates to a resistance heating control device and method for a hot-tightening bolt.
Background
Power plant steam turbine cylinder generally adopts large-scale high strength bolt to tightly heat the bolt and fastens, and hot tight bolt central processing has the through-hole, heats the bolt for the convenience uses the heating rod. At present, a resistance heater is mainly adopted in domestic power plants to heat bolts, and problems of undefined control standard, long heating time and the like exist in the heating fastening and dismounting processes, so that screw thread deformation, middle-section steam leakage and even bolt failure are caused, and further the overhaul period is delayed.
In order to avoid the problems in the resistance heating process of the hot-fastened bolt, the highest temperature, the maximum temperature difference and the maximum temperature rise rate in the heating process need to be determined aiming at bolts of different materials and specifications, the maximum temperature and the maximum stress allowed by the bolts are guaranteed not to be exceeded, the heating time can be effectively shortened, and the fault rate of the bolts can be reduced.
Disclosure of Invention
1. The purpose is as follows:
the invention discloses a resistance heating intelligent control device for a steam turbine hot-fastening bolt, which is used for heating a cylinder hot-fastening bolt, can effectively shorten the heating time, improve the dismounting efficiency and reduce the bolt failure rate.
2. The technical scheme is as follows:
a resistance heating control device for a hot-fastened bolt comprises a direct-current electrical cabinet, a resistance heating rod, a temperature monitoring and feedback device, an elongation measuring device, an intelligent control center and a bolt fastening device; the direct current electrical cabinet is connected with a resistance heating rod through a cable, and the resistance heating rod is inserted into a hot-tightening bolt.
The bolt fastening device comprises a nut, a hot-tightening bolt, a convex washer and a concave washer; the nut is fixedly connected to the upper surface of the flange of the steam turbine cylinder, and the surface of the nut is provided with the adsorption type temperature measuring probe; the concave washer and the convex washer are tightly matched to form a group of washers.
The steam turbine cylinder flange comprises a lower flange and an upper flange; the middle position of the upper surface of the upper flange is sunken, and the gasket is positioned at the sunken position.
The nut is in threaded connection with the hot-tightening bolt; the nut and the upper flange are spaced by a washer.
The elongation measuring device is connected with the intelligent control center.
The adsorption type temperature measuring probe is connected with a temperature measuring instrument, and the temperature measuring instrument is further connected with an intelligent control center.
A resistance heating control method for a hot-fastened bolt comprises the following steps: collecting parameters of the hot tightening bolt, and setting an electric power input curve; step two: assembling devices and establishing conditions; step three: monitoring the heating temperature change; step four: monitoring the disassembly and assembly of the elongation; the third step is that: monitoring the heating temperature change specifically comprises: the resistance heating rod is inserted into the central hole of the hot-fastening bolt, and the effective heating section is set at the polished rod of the hot-fastening bolt; the adsorption type temperature measuring probe tracks and records the temperature of the hot-fastening bolt, and the detection device starts to heat after being normal; during bolt heating, the temperature change of the wall of the nut is monitored at any time, the input power is adjusted according to the change condition, and if the temperature of the nut is found to exceed 100 ℃, the heating is stopped.
The first step is as follows: collecting hot tightening bolt parameters and setting an electric power input curve, and specifically comprises the following steps: collecting information of specifications and models of the hot-tightened bolt and the nut and material, and determining maximum allowable heating temperature, yield strength, maximum allowable stress, maximum allowable temperature change rate of the bolt and maximum allowable temperature parameters of the internal thread of the nut; customizing an optimal heating tool according to the diameter of the bolt, the effective length and the structural information of the heating aperture, wherein control parameters comprise the length, the diameter and the mounting position of a heating rod; after the above data is determined, the electric power input time-varying curve is calculated and changed to be input into the intelligent control center.
The second step is that: the assembling device and the establishing conditions specifically comprise: a bolt resistance heating workbench is built, and the surrounding environment is determined to meet the use requirement of the heater: the temperature of the surrounding medium is not higher than 50 ℃ and not lower than-10 ℃; the relative humidity of air is not more than 95%; the space does not contain chemical corrosion and explosion gases; no vibration and bump are generated, and the installation inclination does not exceed 5 degrees; before the direct current electrical cabinet is electrified, the shell is reliably grounded, and the voltage is regulated to the position of 0.
The fourth step is that: monitoring elongation dismouting specifically includes: before hot tightening, the screwing angle position of the nut 5 is recorded by marking notes, the thread part and the pressure bearing surface of the nut are lubricated by an anti-seizure agent, and the bottom of the central hole is cleaned by compressed air; measuring the elongation change of the bolt in real time by using a bolt elongation measuring device and feeding the elongation change back to an intelligent control center, screwing the nut when the elongation of the bolt reaches the required elongation, checking whether the nut reaches a screwing angle, and stopping heating if the elongation does not reach the required elongation after heating for 60 min; when the bolt elongation measuring device displays that the elongation begins to change during thermal loosening, the nut is disassembled
3. The effect is as follows:
1) ensure the safe operation of the resistance heating process of the hot-tightening bolt
By adopting a direct current heating mode, the output voltage is 0-130V, the waveform is stable, the peak voltage born by the electric heater in the heating process can be reduced by nearly 10 percent compared with the voltage heated by alternating current, the service life of the electric heater is greatly prolonged, and the operation is safer.
Meanwhile, the system software is used for each type of bolt to perform technical analysis and simulation calculation, and fine adjustment and correction are performed on monitoring and adjusting parameters in implementation through multiple heating tests in a laboratory, so that the bolt can be maintained in a usable state even after being heated for 100 times.
2) Intelligent and automatic regulation and control
The bolt can monitor and intelligently analyze and regulate numerical values such as the surface of the nut, the inner wall and the outer wall of the bolt, the flange of the cylinder body, the temperature of a working environment, the elongation of the bolt and the like in a heating process, so that operation and monitoring deviation can be avoided, the dismounting speed is accelerated, and the defect rate of the bolt is reduced. For each bolt, an intelligent control center presets a curve of the change relation of electric power input with time, and the electric power can be automatically adjusted and controlled through monitored temperature and elongation data, so that intelligent and automatic adjustment is realized.
3) Effectively shorten bolt dismouting time, reduce bolt fault rate, improve economic benefits.
Can effectively shorten the heating time, improve dismouting efficiency, can avoid the bolt to take place defects such as seizing, deformation, material degeneration simultaneously, effectively guarantee the fastening requirement of steam turbine cylinder body mid-split.
Drawings
FIG. 1 is a schematic view of a resistance heating apparatus for a steam turbine hot-fastening bolt
FIG. 2 Heat and temperature, elongation measurement of Hot clinch bolts
FIG. 3 is a flow chart
In the figure: 1. the device comprises a power supply, 2, a direct-current electrical cabinet, 3, an intelligent control center, 4, a resistance heating rod, 5, a nut, 6, an elongation measuring device, 7, an adsorption type temperature measuring probe, 8, a turbine cylinder flange, 9, a temperature measuring instrument, 10, a lower flange, 11, an upper flange, 12, a convex gasket, 13, a concave gasket, 14 and a hot-tightening bolt.
Detailed Description
As shown in fig. 1 and 2, the resistance heating intelligent control device for the steam turbine hot-fastening bolt mainly comprises a power-adjustable direct current electric cabinet 2, a resistance heating rod 4, a temperature monitoring and feedback device, an elongation measuring device 6 and an intelligent control center 3:
1) power adjustable dc electrical cabinet 2: the equipment is connected with three-phase alternating current (380V and 50HZ), and is changed into direct current after passing through a rectifier bridge inside the frequency converter, the output voltage is 0-130V (the main loop is continuously adjustable), the waveform is stable, the peak voltage borne by the electric heater in the heating process is reduced by nearly 10 percent compared with the voltage heated by the alternating current, the service life of the electric heater can be greatly prolonged, the output voltage is adjustable, the voltage control is accurate, the service life of the electric heater can be effectively prolonged, and the working efficiency is improved. The load form of the electric appliance cabinet is twelve paths of output, each path of power is positioned by 10KW, and the total power is 120 KW.
2) Resistance heating rod 4: through the finite element analysis model, carry out 4 optimal designs of resistance heating rod to different materials, specification model, fastening mode bolt, confirm 4 parameters of resistance heating rod that the heating effect is optimal: the method comprises the steps of analyzing and researching the heating working condition of the hot-fastening bolt 14, including the diameter, the length, the installation position and the like of the resistance heating rod 4, and determining the installation range of the heating rod and the influence on the temperature, the stress and the elongation of the hot-fastening bolt 14.
3) Temperature monitoring and feedback device: an adsorption temperature measuring probe is arranged on the surface of the nut 5 and connected with a temperature measuring instrument, the surface temperature and the change of the nut 5 are monitored in real time, data measured by the temperature measuring instrument 9 are uploaded to the intelligent control center 3 in time, the intelligent control center 3 analyzes the maximum temperature, the maximum temperature difference, the maximum temperature rise rate and the thread temperature of the nut 5 of the hot-tightening bolt 14 according to the power of the heating rod and the recorded temperature, and the heating power is adjusted in real time.
4) Bolt elongation measuring device 6: and an elongation measuring device 6 is arranged on the nut 5, and is used for measuring the elongation of the bolt and feeding back the elongation to the intelligent control center 3.
5) The intelligent control center 3: and a professional computer is equipped and comprises intelligent calculation and analysis software, and the software contains characteristic parameters (including bolt material, morphology, maximum allowable heating temperature, maximum allowable temperature difference, maximum allowable temperature variability, maximum allowable nut internal thread temperature, heating power output and process control curve, actual measurement and predicted heating time and the like) of the bolt with the required heating specification. The software can read and calculate the temperature of the selected point of the bolt in the heating process, and the calculated information such as the internal thread temperature of the nut 5, the maximum temperature in the hot-tightening bolt 14, the maximum temperature difference, the variation trend, the preset allowable threshold value and the like is obtained. When the difference between the actual monitored temperature distribution and the preset temperature distribution is within 10%, heating according to a preset value until the required elongation of the hot-tightened bolt 14 is reached; when the difference between the actual monitored temperature distribution and the preset temperature distribution is more than 10%, heating according to a predicted power curve is realized by properly adjusting the output power, and when the temperature monitoring parameter exceeds the standard (namely exceeds the highest heating allowable temperature, the maximum allowable temperature difference, the highest allowable temperature variability, the highest allowable temperature of the internal thread of the nut 5 and the like), the system sends out an alarm to stop heating, and the heating process is as follows.
The intelligent control center 3 is also provided with a relation model curve which is established by theoretical calculation and experimental verification and aims at the temperature change, the elongation change and the power output change of each type of bolt, and the intelligent control center can automatically adjust the power output according to the actually measured temperature and elongation change conditions. After the heating is finished, the power change and temperature change data of the heating are recorded in detail in seconds, and meanwhile, the data are stored and applied to the next bolt with the same specification.
The invention has the advantages that
1) The intelligent control center 3 software analysis method is based on a bolt thermal-stress coupling field finite element analysis model, aims at bolts and resistance heating rod 4 materials with different materials, specification models and fastening modes, takes the highest heating temperature, the maximum temperature difference, the maximum temperature rise rate and the thread temperature at a nut as limiting conditions, and determines an optimal heating power curve through simulation calculation.
2) Aiming at bolts of different materials, specifications and types and fastening modes, parameters such as the diameter of the heating rod, the effective heating length, the mounting position and the like are optimized and analyzed, 4 parameters of the resistance heating rod with the optimal heating effect are determined, and the optimal heating power output can be realized.
3) Temperature sensing probes are arranged on the surface of the nut 5, the inner wall and the outer wall of the stud and the flange of the cylinder body, the temperature sensing probes are read and displayed by a temperature recorder, the data measured by the temperature recorder are all input to the intelligent control center 3, the limiting parameters and the variation trend such as the thread temperature at the nut 5, the maximum temperature and the maximum temperature difference value in the hot-tightening bolt 14 and the like are calculated by analysis software in the intelligent control center 3 and are compared with a preset threshold value, and the intelligent regulation and control of the input power are realized.
4) The upper end face of the nut 5 is provided with an elongation measuring device for measuring the elongation change of the hot tightening bolt 14 in real time, and data are transmitted to the intelligent control center 3 and compared with a preset value and an elongation curve, so that excessive elongation is avoided.
The specific implementation steps are as follows:
1. setting electric power input curves according to different hot-tightening bolts before implementation
Before heating, collecting information such as specification, model and material of the hot-tightening bolt 14 and the nut 5, and determining maximum allowable heating temperature, yield strength, maximum allowable stress, maximum allowable temperature change rate of the bolt 14 and maximum allowable temperature parameters of the internal thread of the nut 5. Meanwhile, according to structural information such as the diameter, the effective length and the heating aperture of the bolt 14, an optimal heating tool is customized (control parameters comprise the length, the diameter and the mounting position of a heating rod). After the above data is determined, a curve of the change of electric power input with time is calculated and changed to be input into the intelligent control center 3.
2. Pre-enforcement assembly device and set-up conditions
As shown in the attached figure 1, a bolt resistance heating workbench is built, and the surrounding environment is determined to meet the use requirement of a heater: 1. the temperature of the surrounding medium is not higher than 50 ℃ and not lower than-10 ℃; 2. the relative humidity of air is not more than 95%; 3. the space does not contain chemical corrosion and explosion gases; 4. no vibration and bump are generated, and the installation inclination does not exceed 5 degrees; 5. before the control cabinet 2 is powered on, the shell should be reliably grounded, and the voltage should be adjusted to the '0' position.
3. Monitoring temperature changes during heating
As shown in fig. 2, the bolt fastening means is composed of a nut 5, a heat-tightened bolt 14, a male washer 12, and a female washer 13 for fastening the upper and lower flanges 8. The resistance heating rod 4 is inserted into the central hole of the hot-fastening bolt 14, and the effective heating section is set at the polished rod of the hot-fastening bolt, so that the internal thread of the nut is prevented from being overheated.
An adsorption temperature measuring probe 7 is arranged at the nut 5 and connected with a temperature measuring instrument 9 for tracking and recording the temperature of the hot-fastening bolt 14; and starting heating operation after the detection device is normal. During the heating of the screw 14, the wall temperature change of the nut 5 is monitored at all times, the input power is adjusted according to the change situation, and if the temperature of the nut 5 is found to exceed 100 ℃, the heating is stopped.
4. Monitoring elongation change and carrying out disassembly and assembly work in heating process
Before hot tightening, the screwing angle position of the nut 5 is recorded by marking notes, the threaded part and the pressure bearing surface of the nut 5 are lubricated by an anti-seizure agent, and the bottom of the central hole is cleaned by compressed air. And measuring the elongation change of the bolt 14 in real time by using the elongation measuring device 6 of the bolt 14 and feeding the elongation change back to the intelligent control center 3, screwing the nut 5 when the elongation of the bolt 14 reaches the required elongation, checking whether the nut 5 reaches a screwing angle, and stopping heating if the required elongation is not reached after heating for 60 min. When the bolt 14 is thermally loosened, the nut 5 can be removed when the elongation measuring device displays that the elongation begins to change.
Claims (10)
1. The utility model provides a hot tight bolt resistance heating controlling means which characterized in that: the device comprises a direct-current electrical cabinet (2), a resistance heating rod (4), a temperature monitoring and feedback device, an elongation measuring device (6), an intelligent control center (3) and a bolt fastening device; the direct current electrical cabinet (2) is connected with a resistance heating rod (4) through a cable, and the resistance heating rod (4) is inserted into a hot-tightening bolt (14).
2. A hot-water bolt resistance heating control device as claimed in claim 1, wherein: the bolt fastening device comprises a nut (5), a hot-tightening bolt (14), a convex gasket (12) and a concave gasket (13); the nut (5) is fixedly connected to the upper surface of a turbine cylinder flange (8), and an adsorption type temperature measuring probe (7) is arranged on the surface of the nut (5); the concave washer (12) and the convex washer (13) are tightly matched to form a group of washers.
3. A hot-water bolt resistance heating control device as claimed in claim 2, wherein: the steam turbine cylinder flange (8) comprises a lower flange (10) and an upper flange (11); the middle position of the upper surface of the upper flange (11) is sunken, and the gasket is positioned at the sunken position.
4. A hot-water bolt resistance heating control device as claimed in claim 2, wherein: the nut (5) is in threaded connection with the hot-tightening bolt (14); a washer is arranged between the nut (5) and the upper flange (11).
5. A hot-water bolt resistance heating control device as claimed in claim 1, wherein: the elongation measuring device (6) is connected with the intelligent control center (3).
6. A hot-water bolt resistance heating control device as claimed in claim 1, wherein: the adsorption type temperature measuring probe (7) is connected with a temperature measuring instrument (9), and the temperature measuring instrument (9) is further connected with the intelligent control center (3).
7. A resistance heating control method for a hot-tightening bolt is characterized by comprising the following steps: the method comprises the following steps: collecting parameters of the hot-tightening bolt (14) and setting an electric power input curve; step two: assembling devices and establishing conditions; step three: monitoring the heating temperature change; step four: monitoring the disassembly and assembly of the elongation; the third step is that: monitoring the heating temperature change specifically comprises: the resistance heating rod (4) is inserted into a central hole of the hot-fastening bolt (14), and an effective heating section is set at the polished rod of the hot-fastening bolt; the adsorption type temperature measuring probe (7) tracks and records the temperature of the hot-tightening bolt (14), and the detection device starts to heat after being normal; during the heating of the bolt (14), the wall temperature change of the nut (5) is monitored at all times, the input power is adjusted according to the change situation, and if the temperature of the nut (5) is found to exceed 100 ℃, the heating is stopped.
8. The resistance heating control method for the hot-tightened bolt according to claim 7, characterized in that: the first step is as follows: collecting hot-fastening bolt (14) parameters and setting an electric power input curve, which specifically comprises the following steps: collecting specification, model and material information of the hot-tightening bolt (14) and the nut (5), and determining maximum allowable heating temperature, yield strength, maximum allowable stress, maximum allowable temperature change rate of the bolt (14) and maximum allowable temperature parameters of the internal thread of the nut (5); customizing an optimal heating tool according to the diameter, the effective length and the heating aperture structure information of the bolt (14), wherein control parameters comprise the length, the diameter and the mounting position of a heating rod; after the above data is determined, the curve of the electric power input with time is calculated and changed to be input into the intelligent control center (3).
9. The resistance heating control method for the hot-tightened bolt according to claim 7, characterized in that: the second step is that: the assembling device and the establishing conditions specifically comprise: a bolt resistance heating workbench is built, and the surrounding environment is determined to meet the use requirement of the heater: the temperature of the surrounding medium is not higher than 50 ℃ and not lower than-10 ℃; the relative humidity of air is not more than 95%; the space does not contain chemical corrosion and explosion gases; no vibration and bump are generated, and the installation inclination does not exceed 5 degrees; before the direct current electrical cabinet (2) is electrified, the shell is reliably grounded, and the voltage is regulated to the 0 position.
10. The resistance heating control method for the hot-tightened bolt according to claim 7, characterized in that: the fourth step is that: monitoring elongation dismouting specifically includes: before hot tightening, the screwing angle position of the nut 5 is recorded by marking notes, the thread part and the pressure bearing surface of the nut (5) are lubricated by an anti-seizure agent, and the bottom of the central hole is cleaned by compressed air; measuring the elongation change of the bolt (14) in real time by using the elongation measuring device (6) of the bolt (14) and feeding the elongation change back to the intelligent control center (3), screwing the nut (5) when the elongation of the bolt (14) reaches the required elongation, checking whether the nut (5) reaches the screwing angle, and stopping heating if the required elongation is not reached after heating for 60 min; when the bolt (14) is loosened thermally, the nut (5) is disassembled when the elongation measuring device displays that the elongation begins to change.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111210125.3A CN113909800A (en) | 2021-10-18 | 2021-10-18 | Resistance heating control device and method for hot-fastening bolt |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111210125.3A CN113909800A (en) | 2021-10-18 | 2021-10-18 | Resistance heating control device and method for hot-fastening bolt |
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| Publication Number | Publication Date |
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| CN113909800A true CN113909800A (en) | 2022-01-11 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202111210125.3A Pending CN113909800A (en) | 2021-10-18 | 2021-10-18 | Resistance heating control device and method for hot-fastening bolt |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114700681A (en) * | 2022-04-13 | 2022-07-05 | 西安交通大学 | Convection heating device for hot tightening of split bolt in cylinder and use method thereof |
-
2021
- 2021-10-18 CN CN202111210125.3A patent/CN113909800A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114700681A (en) * | 2022-04-13 | 2022-07-05 | 西安交通大学 | Convection heating device for hot tightening of split bolt in cylinder and use method thereof |
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