CN110052777B - On-site repairing method suitable for pit cavity space - Google Patents
On-site repairing method suitable for pit cavity space Download PDFInfo
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Abstract
The invention provides a field repairing method suitable for a pit cavity space, which adopts an arc welding robot, field numerical control machining and medium-frequency induction internal and external heating technology, eliminates the defects of body cracks, valve seat cracks and the like of an inner cavity of a valve body of a main steam high-pressure regulating valve, ensures the safety of power generation equipment as the repaired valve reaches the factory level, and provides a method and a technical route for solving the major equipment hidden troubles of high-temperature high-pressure steam valves of the same type of units in a short time on site.
Description
The present application is a divisional application of the following original applications:
application date of the original application: 09 month and 30 days 2018
- -application number of the original application: 201811163163.6
- -name of invention of original applicationWeighing: on-site repairing method suitable for pit cavity space
Technical Field
The invention relates to the field of on-site repair of a unit, in particular to an on-site repair method suitable for a pit cavity space, and particularly relates to an on-site repair method of a main steam regulating valve of a gas turbine unit based on an arc welding robot.
Background
The power plant has higher requirements on the annual start-stop times of the units of the single-shaft gas-steam combined cycle and the like, and the annual start-stop times are not less than 200 generally. In the disassembly maintenance of the main steam regulating valve, the valve seat sealing surface is one of the objects to be maintained. For the condition that a plurality of cracks exist at the position of the sealing surface of the valve seat, the main characteristics are that the cracks are radially and circumferentially arranged on the outer circle along the radial direction, and the economy of the generator set and the normal operation of equipment are directly influenced. However, the space in the valve cavity is narrow, and the valve seat is positioned in a deep pit position, so that the valve seat is not suitable for returning to a factory for repair, and therefore on-site automatic equipment and technology are needed to be adopted for repairing the valve seat.
Disclosure of Invention
In view of the defects in the prior art, the invention aims to provide an on-site repairing method suitable for a pit cavity space.
The invention provides an on-site repairing method suitable for a pit cavity space, which comprises the following steps:
turning and removing the part of the surface to be processed with the defects;
planning to perform arc welding by using a robot;
heating inside and outside through medium frequency induction;
and welding and repairing the part of the surface to be processed by using the robot.
Preferably, the turned areas include a weld overlay material and a weld heat affected zone; after the turning is finished, the optical spectrum inspection is confirmed and the coloring inspection is carried out to ensure that the defects are all cleared.
Preferably, the step of arc welding by robot includes:
an off-line simulation step: establishing a virtual model of the pit cavity in an off-line manner, determining the length, the shape and the posture of a matched welding gun according to the structure of the pit cavity, virtually teaching the movement track and the movement path of the welding gun, and determining that the welding track and the posture are not in conflict with the internal structure of the pit cavity;
parameter transplanting step: the robot is linked with a positioner in a laboratory to simulate the position and the posture of a part of a surface to be processed on site, a working state and a mode which are the same as those of an on-site on-line repair environment are constructed, a whole set of process parameters are obtained through simulation, and the parameters of off-line simulation are transplanted to the site;
a robot three-point teaching step: calculating the circle center through three-point positioning, thereby planning the track of a circle and completing teaching work;
and (3) planning a welding bead and a track: multilayer multi-pass welding is required, and when welding is actually carried out, the multilayer multi-pass welding path planning is completed according to the established space geometric coordinate diagram by the following steps:
1) three-point position finding;
2) calculating a new tool coordinate system according to the height difference and the radius difference of the flange edge of the part of the welding surface and the surface to be processed in the drawing;
3) for multilayer and multi-pass surfacing, determining offset according to the welding thickness of each pass, and performing welding track precision calibration; then, dividing and deviating the track of the circle according to the process requirements, and determining different initial and end welding positions according to the geometric positions to meet the technical requirements of welding joint staggering;
determining the extra height and width of each welding seam according to welding current, wire feeding speed and welding speed parameters through a process test, and further completing the implementation of multilayer welding beads by utilizing a welding offset program, namely determining the position height of the welding bead in the Z direction and determining the relative offset position of the welding bead in the Y direction; inputting Z-direction and Y-direction position deviation values of a subsequent welding pass in the arc welding robot in the whole welding process to realize welding according to a pre-planned track and speed.
Preferably, the step of heating inside and outside by medium frequency induction comprises:
for the inner wall heat treatment, an internal heating induction heating coil is fixed on an L-shaped movable plate, and a water-cooling cable for connecting a heating power supply and the internal heating induction coil is well connected; before welding or repairing, the internal heating induction coil is moved to a flange opening of the pit cavity through a lifting table tool, and then enters the cavity of the pit cavity until reaching the position of a surface to be processed;
for the outer wall heat treatment, the flexible air-cooled heating cable is directly wound on the outer wall of the part to which the surface to be processed belongs, the flexible air-cooled heating cable is in a working state all the time from the preheating of the part to which the surface to be processed belongs to the whole welding process, and a heat dam is formed on the outer wall of the flexible air-cooled heating cable;
the inner wall and the outer wall are subjected to heat treatment simultaneously, only the internal heating induction heating coil is removed after the preheating temperature is constant, and the outer wall is subjected to heat treatment at a constant temperature to ensure the interlayer temperature in the welding or repairing process; after welding or repairing is finished, the internal heating induction heating coil enters, and the post-welding heat treatment is started at the same temperature rise rate, constant temperature time and temperature reduction rate as the external heating coil until the whole heat treatment process is completely finished.
Preferably, the step of performing welding repair on the surface part to be processed by using a robot includes:
preheating: preheating before welding and preserving heat by adopting field heat treatment equipment, measuring the temperature by using an infrared thermometer after the heat preservation is finished, and executing the next repair welding step after the range is met;
repair welding: overlaying the defect eliminating part of the surface to be processed by adopting an arc welding robot, and restoring the overlaying size to the original size; adopting layered and divided welding; after repair welding, heat preservation and heat treatment are carried out, and finally, the heat treatment is carried out after overlaying welding of the sealing surface;
turning a surfacing groove: carrying out surfacing groove machining on the surfacing surface by adopting numerical control machining equipment, and carrying out coloring inspection on the groove surface and the surfacing position;
surfacing: preheating the surfacing welding, and performing surfacing welding by adopting layering and shunting;
a heat treatment step: the heat treatment temperature is consistent with the tempering temperature of the base material, and the heating rate, the heat preservation temperature, the heat preservation time, the cooling rate and the unpacking temperature are all displayed by monitoring thermocouples as the standard;
and (3) forming and machining: confirming the contour dimension of the final surface to be processed, carrying out numerical control programming and confirming the program to be correct, and finally carrying out forming processing on the surface to be processed.
Preferably, the surface to be processed is a sealing surface, and the part to which the surface to be processed belongs is a valve seat.
Preferably, a post-repair inspection step is also included.
Compared with the prior art, the invention has the following beneficial effects:
the invention adopts the arc welding robot, the on-site numerical control processing and the medium-frequency induction internal and external heating technology, eliminates the defects of body cracks, valve seat cracks and the like of the inner cavity of the valve body of the main steam high-pressure regulating valve, ensures the safety of power generation equipment as the repaired valve reaches the delivery level, and provides a method and a technical route for solving the major equipment hidden trouble of the high-temperature high-pressure steam valve of the same type of unit on site in a short time.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
fig. 1 is a schematic structural diagram of a valve seat in a valve.
FIG. 2 is a route diagram of a main steam regulating valve field repair technology.
FIG. 3 is a secondary machining path planning diagram.
Fig. 4 is a schematic diagram of the correlation between the three-point teaching and the weld bead planning.
Fig. 5 is a schematic diagram of an inner wall induction coil structure.
The figures show that:
valve seat sealing surface 101
Bonnet bore 102
Screw hole 103
Valve cover position 104
Valve seat end face position 105
Arc surface lower edge 106
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
The invention provides an on-site repairing method suitable for a pit cavity space, which comprises the following steps:
turning and removing the part of the surface to be processed with the defects;
planning to perform arc welding by using a robot;
heating inside and outside through medium frequency induction;
and welding and repairing the part of the surface to be processed by using the robot.
Preferably, the turned areas include a weld overlay material and a weld heat affected zone; after the turning is finished, the optical spectrum inspection is confirmed and the coloring inspection is carried out to ensure that the defects are all cleared.
Preferably, the step of arc welding by robot includes:
an off-line simulation step: establishing a virtual model of the pit cavity in an off-line manner, determining the length, the shape and the posture of a matched welding gun according to the structure of the pit cavity, virtually teaching the movement track and the movement path of the welding gun, and determining that the welding track and the posture are not in conflict with the internal structure of the pit cavity;
parameter transplanting step: the robot is linked with a positioner in a laboratory to simulate the position and the posture of a part of a surface to be processed on site, a working state and a mode which are the same as those of an on-site on-line repair environment are constructed, a whole set of process parameters are obtained through simulation, and the parameters of off-line simulation are transplanted to the site;
a robot three-point teaching step: calculating the circle center through three-point positioning, thereby planning the track of a circle and completing teaching work;
and (3) planning a welding bead and a track: multilayer multi-pass welding is required, and when welding is actually carried out, the multilayer multi-pass welding path planning is completed according to the established space geometric coordinate diagram by the following steps:
1) three-point position finding;
2) calculating a new tool coordinate system according to the height difference and the radius difference of the flange edge of the part of the welding surface and the surface to be processed in the drawing;
3) for multilayer and multi-pass surfacing, determining offset according to the welding thickness of each pass, and performing welding track precision calibration; then, dividing and deviating the track of the circle according to the process requirements, and determining different initial and end welding positions according to the geometric positions to meet the technical requirements of welding joint staggering;
determining the extra height and width of each welding seam according to welding current, wire feeding speed and welding speed parameters through a process test, and further completing the implementation of multilayer welding beads by utilizing a welding offset program, namely determining the position height of the welding bead in the Z direction and determining the relative offset position of the welding bead in the Y direction; inputting Z-direction and Y-direction position deviation values of a subsequent welding pass in the arc welding robot in the whole welding process to realize welding according to a pre-planned track and speed.
Preferably, the step of heating inside and outside by medium frequency induction comprises:
for the inner wall heat treatment, an internal heating induction heating coil is fixed on an L-shaped movable plate, and a water-cooling cable for connecting a heating power supply and the internal heating induction coil is well connected; before welding or repairing, the internal heating induction coil is moved to a flange opening of the pit cavity through a lifting table tool, and then enters the cavity of the pit cavity until reaching the position of a surface to be processed;
for the outer wall heat treatment, the flexible air-cooled heating cable is directly wound on the outer wall of the part to which the surface to be processed belongs, the flexible air-cooled heating cable is in a working state all the time from the preheating of the part to which the surface to be processed belongs to the whole welding process, and a heat dam is formed on the outer wall of the flexible air-cooled heating cable;
the inner wall and the outer wall are subjected to heat treatment simultaneously, only the internal heating induction heating coil is removed after the preheating temperature is constant, and the outer wall is subjected to heat treatment at a constant temperature to ensure the interlayer temperature in the welding or repairing process; after welding or repairing is finished, the internal heating induction heating coil enters, and the post-welding heat treatment is started at the same temperature rise rate, constant temperature time and temperature reduction rate as the external heating coil until the whole heat treatment process is completely finished.
Preferably, the step of performing welding repair on the surface part to be processed by using a robot includes:
preheating: preheating before welding and preserving heat by adopting field heat treatment equipment, measuring the temperature by using an infrared thermometer after the heat preservation is finished, and executing the next repair welding step after the range is met;
repair welding: overlaying the defect eliminating part of the surface to be processed by adopting an arc welding robot, and restoring the overlaying size to the original size; adopting layered and divided welding; after repair welding, heat preservation and heat treatment are carried out, and finally, the heat treatment is carried out after overlaying welding of the sealing surface;
turning a surfacing groove: carrying out surfacing groove machining on the surfacing surface by adopting numerical control machining equipment, and carrying out coloring inspection on the groove surface and the surfacing position;
surfacing: preheating the surfacing welding, and performing surfacing welding by adopting layering and shunting;
a heat treatment step: the heat treatment temperature is consistent with the tempering temperature of the base material, and the heating rate, the heat preservation temperature, the heat preservation time, the cooling rate and the unpacking temperature are all displayed by monitoring thermocouples as the standard;
and (3) forming and machining: confirming the contour dimension of the final surface to be processed, carrying out numerical control programming and confirming the program to be correct, and finally carrying out forming processing on the surface to be processed.
Preferably, the surface to be processed is a sealing surface, and the part to which the surface to be processed belongs is a valve seat.
Preferably, a post-repair inspection step is also included.
The invention is further illustrated in detail below by a preferred embodiment, exemplified by a class F single shaft gas steam combined cycle unit.
Step 1: survey main steam regulating valve technical requirement and field mapping
1.1: investigating the technical requirements of the main steam regulating valve
The valve body material of the main steam regulating valve conforms to the standard SA182-F22, the valve seat is of an integrated structure, namely, a sealing surface is directly welded on the valve body in a surfacing mode, and the surfacing material is 12% Cr Steel (AWS ER-410). The sealing surface of the valve core of the main steam regulating valve is subjected to Stellite6 alloy surfacing, and the valve core and the sealing surface are combined in a relatively soft and hard mode, so that the tightness of the sealing surface of a gas turbine unit is guaranteed under the condition of high-frequency starting and stopping.
1.2: on-site surveying and mapping
After on-site surveying and mapping and size rechecking, the valve seat of the main steam regulating valve is of a cambered surface structure; the maximum diameter of the sealing surface of the valve seat is 289.17 mm; the diameter of the inner hole of the valve cover is 345.5 mm; the center distance of the screw hole is 520 mm; the height from the valve cover to the end face of the valve seat is 770mm, and the height from the valve cover to the lower edge of the arc surface is 855.01 mm; the throat diameter is 184mm, see figure 1. According to the measurement result, the space in the valve cavity is narrow, the valve seat is positioned at the deep pit part, the surface to be repaired cannot be repaired according to a conventional manual method, and in order to ensure the repair quality and the repair feasibility, an automatic field repair scheme of a robot, numerical control machining and online heat treatment is formulated.
Step 2: drawing up the technical route of field repair
In order to ensure that the repair quality of the valve seat of the main steam regulating valve reaches the factory level, after mastering the manufacturing process, aiming at the field environment and conditions, according to the field measurement result, the invention sets up the field repair work technical route shown in figure 2. If blowing damage, cracks, air holes and falling-off do not exist, the object needing to be repaired is not found, and the work is finished; if the technical requirements are not met, returning to execute the damaged surface machining again; if the preheating temperature does not reach the requirement, returning to perform heating of the inner wall and the outer wall again; if the overlaying quality does not meet the requirement, returning to perform the robot pit overlaying again; if the heat treatment is not finished, returning to continue to use the internal heating device for heating; if the machining size and the surface hardness do not meet the requirements, returning to execute the repairing surface machining again; and if the grinding precision and the sealing surface combination do not meet the requirements, returning to execute the grinding device again.
And step 3: on-site numerical control machining
3.1: processing tool of manufacturing machine
The key core of the field machining is how to position the machining, the machining reference is determined, the concentric surface of the surface to be machined and the flange surface are considered, the positioning tool is manufactured according to the size mapping of the field equipment, wherein the positioning tool comprises a fixed flange, a supporting upright post, a positioning block and the like which are matched with a valve cover, and the auxiliary tools can ensure the strength and precision requirements of the field machining equipment. The technical personnel in the field can combine the prior art to realize the processing of the auxiliary tool, and the auxiliary tool is not the key point of the invention and is not described herein again.
3.2: installation and commissioning device
And installing a positioning tool and a numerical control machining device on the valve cover of the main steam regulating valve, and performing numerical control machining programming and equipment debugging according to the size technical requirement of the valve seat of the main steam regulating valve.
3.3: machining process control
3.3.1: in situ machining and inspection
The part of the sealing surface of the valve seat with defects is turned completely, and the turning area comprises an original overlaying layer material and a welding heat affected area (the thickness is determined to be 10mm), and then the spectrum inspection and the coloring inspection are carried out to ensure that the defects of the valve body are completely removed.
3.3.2: secondary machining path planning
In the implementation process of the repair scheme, the nondestructive test result shows that the valve body also has defects, and the depth of the crack is about 35mm, so that the second turning is carried out on part of the defects. At the same time, in order to prevent the damage of the turning to the valve body, the turning size is further planned, and the planning can reduce the damage of the valve body as much as possible, as shown in fig. 3.
3.3.3: content of machining
According to the defect condition of the main steam regulating valve, the field machining work is divided into three parts, including original overlaying layer defect elimination, valve body defect machining and valve seat sealing surface forming after repair overlaying.
And 4, step 4: planning for arc welding with robotic arc welding techniques
Because the depth of the part to be subjected to surfacing repair is larger than 800mm, the method belongs to deep pit surfacing in a narrow space. Meanwhile, the on-site maintenance period is short, and the quality of the repaired product can reach or exceed the factory level only by adopting a hot welding method. Thus, the possibility of manual repair is substantially eliminated. The method can better overcome the limitations of field environment and conditions by utilizing the technologies of off-line simulation, parameter transplantation, three-point teaching, welding bead and track planning in a narrow space and the like of the arc welding robot.
4.1: off-line simulation
Considering that the valve has a special structure, a welding gun and a certain posture are required to be adopted to finish a repair task, so that whether the length, the shape and the posture of the welding gun can meet the welding requirement or not needs to be determined before the integral design, and meanwhile, the welding track and the posture need to be determined to have no conflict with the internal structure of the valve. In order to optimize the design, a valve virtual model is established off line, and the movement track and path of a welding gun are taught virtually in the Robot studio, so that the pre-design of the track, the posture and the path of the welding gun, the tool, the clamp and the size of the welding gun is realized.
4.2: parameter migration
Because the period of on-site on-line repair is generally short and the time for on-site on-line construction is limited, basic parameters such as the motion track, the welding current, the voltage, the speed, the welding gun track and the like of the robot must be acquired before the robot enters the site. Therefore, the robot and the high-tonnage positioner are linked in a laboratory to simulate the position and the posture of a field valve, the working state and the mode which are the same as those of a field online repair environment are constructed, a whole set of process parameters are obtained through simulation, the parameters of offline simulation are transplanted to the field, and the high efficiency and the high quality of field repair can be ensured only through online fine adjustment.
4.3: robot three-point teaching
The internal space of the valve is relatively narrow, which is also a main reason why manual repair is impossible. Similarly, certain technical difficulty is caused to the teaching work of the robot. According to the structural design and the manufacturing and processing process characteristics of the valve body, the valve sealing surface and the end surface of the valve cover flange are a circle center circle, and the concentricity is good. Meanwhile, according to the geometric principle, only 3 points are needed to determine a circle. Therefore, when the robot teaches, the center of a circle can be calculated through three-point positioning by utilizing the internal operation function of the robot, so that the track of a circle is planned, and teaching work is completed quickly.
4.4: weld bead and trajectory planning in narrow spaces
The valve body and the part of the sealing surface needing surfacing have certain thickness, and meanwhile, the dilution rate of the welding process needs to be controlled, and a single layer and a single channel cannot complete the repair scheme, so that multiple layers and multiple channels of welding need to be adopted. When actually welding, under the premise of establishing a space geometric coordinate diagram, the multi-layer and multi-channel welding bead planning can be completed only by the following steps:
1) three-point seek (by teach or laser seek);
2) calculating a new tool coordinate system according to the height difference and the radius difference between a welding surface and the flange edge in a drawing, namely only the difference between the delta H value and the delta r value needs to be input;
3) for multi-layer and multi-path surfacing, establishing an offset according to the welding thickness of each path, and performing welding track precision calibration, namely only inputting a delta H1 value and a delta r1 value; then, the tracks of the circles are segmented and deviated according to the process requirements, so that different initial welding positions and different final welding positions can be determined according to the geometric positions, and the technical requirement of staggering welding joints is met.
Meanwhile, the extra height and the width of each welding bead can be established according to parameters such as welding current, wire feeding speed, welding speed and the like through a series of process tests, and then the implementation of multilayer welding beads is completed by utilizing a welding offset program, namely the position height of the welding bead is established in the Z direction, and the relative offset position of the welding bead is established in the Y direction. Therefore, in the whole welding process, the welding can be carried out according to the pre-planned track and speed only by inputting the Z-direction and Y-direction position offset values of the subsequent welding pass in the arc welding robot, and the re-teaching work for each welding seam is not needed.
And 5: medium frequency induction internal and external heating
The valve body and the sealing surface of the main steam regulating valve are complex in appearance and changeable in wall thickness. If the traditional outer wall heating conduction heating method is adopted, the temperature difference is large. The medium-frequency induction internal and external heating technology can ensure that the requirements of a heating process and a working time sequence are met in the welding or repairing process according to the sealing surface structure of the on-site high-temperature and high-pressure steam valve and the complexity of the environment. As shown in table 1.
TABLE 1 heating operation sequence
When heat treatment is needed, the tool is fixed on the valve cover by utilizing a valve end cover bolt, then the internal heating induction heating coil is fixed on the L-shaped movable disc, and the heating power supply and the water-cooling cable of the induction coil are connected. Before welding or repairing, the induction coil is moved to a valve cover flange opening of the valve body through the lifting table tool, and then enters the valve cavity until the inner hole position of the sealing surface. For the outer wall heat treatment, a flexible air cooling heating cable can be directly wound on the outer wall of the irregular valve body, the flexible air cooling heating cable is in a working state all the time from the beginning of preheating of the valve to the end of the whole welding process, a thermal dam is formed on the outer wall of the valve to prevent excessive heat dissipation so as to ensure the heating effect of a sealing surface, the inner wall and the outer wall start to work simultaneously during the heat treatment, only the inner heating coil is withdrawn after the preheating temperature is constant, the outer wall continues to be at a constant temperature so as to ensure the interlayer temperature in the welding or repairing process, and after the welding or repairing is finished, the inner heating coil enters and starts to perform the post-welding heat treatment at the same heating rate, constant temperature time and.
Step 6: repair process control
The repair work comprises two parts, namely a main steam regulating valve seat sealing surface and an adjacent valve body, and the valve body must be repaired first and then the sealing surface is subjected to surfacing welding. The materials are different, and the selected repairing and surfacing materials are different in different processes, which is shown in table 2. Therefore, the technical difficulty is high and the process is complex. Therefore, the repair process must be made reasonably and accurately, and the whole process is strictly controlled.
TABLE 2 repair and build-up welding materials
6.1: preheating
On the premise of confirming that all turning defects are eliminated, on-site heat treatment equipment is adopted for preheating before welding, so that the installation and debugging of the heat treatment equipment are completed, and preheating is carried out after the defects are confirmed to be correct. The preheating temperature is 250 ℃ and 300 ℃, and the heat preservation is carried out for 1 h. And after the heat preservation is finished, the temperature is measured by using an infrared thermometer, and the next procedure can be executed after the meeting range is met.
6.2: repair welding of valve body
And (4) performing surfacing welding on the missing part of the valve body by adopting an arc welding robot, and recovering the surfacing welding size to the original sealing surface size. The layered and divided welding is adopted, the interlayer temperature is strictly controlled to be 300-350 ℃, the welding seam is well formed, the appearance is smooth, and the defects of undercut and the like are avoided. And after repair welding, performing heat treatment at 350-400 ℃ for 2h, and performing final heat treatment after overlaying welding of the sealing surface.
6.3: turning of surfacing groove of sealing surface
Carrying out surfacing groove machining on the surfacing surface of the valve body by using numerical control machining equipment, wherein the depth of the groove is not less than 7 mm; and (4) carrying out coloring inspection on the bevel face and the surfacing position to meet NB/T47013, wherein the grade I is qualified.
6.4: surfacing of sealing surfaces
Preheating the surfacing welding at the preheating temperature of 300-350 ℃. And (4) performing surfacing welding on the sealing surface by adopting layering and shunting. The interlayer temperature is strictly controlled to be 300-350 ℃, the welding line is well formed, the appearance is smooth, and the defects of undercut and the like are avoided.
6.5: thermal treatment
As the surfacing material of the sealing surface of the valve seat is AWS ER-410, the valve seat needs to be cooled to below MS point after welding to perform martensite temperature transformation, and then temperature rise heat treatment is performed. The heat treatment temperature is kept consistent with the tempering temperature of the base material, the constant temperature time is delta/25 multiplied by 2(h), the temperature rise and reduction speed is 6250 delta and not more than 150 ℃/h, and the heat insulation cotton is disassembled at the temperature of not more than 80 ℃. The complete process curve, the heating rate, the heat preservation temperature and the heat preservation time are reserved
The cooling speed and the unpacking temperature are both based on the display of a monitoring thermocouple.
6.6: machining by forming machines
And confirming the final contour dimension of the sealing surface according to the manufacturing technical standard and the field surveying and mapping dimension of the main steam regulating valve, performing numerical control programming and confirming the program to be correct, and finally performing the forming processing of the sealing surface, wherein the surface processing precision is less than 0.4 mu m.
And 7: post repair inspection
The repaired main steam regulating valve must reach the quality acceptance standard of delivery, including nondestructive testing, hardness testing, check of a sealing surface valve line and the like. The hardness test is carried out after the heat treatment is finished and comprises a body and a valve seat sealing surface, and the hardness value range is HB (200-260). Through final inspection, the on-site repair quality of the main steam high-pressure regulating valve reaches the expected effect.
In summary, in the preferred embodiment, aiming at the repairing characteristics that the space in the valve cavity is narrow and the valve seat is located in the deep pit, the defects of body cracks, valve seat cracks and the like of the inner cavity of the main steam high-pressure governing valve body of the F-level single-shaft gas-steam combined cycle unit are eliminated by formulating and executing an automatic repairing scheme of robot, numerical control machining and online heat treatment, and the repaired quality meets various technical requirements. The comprehensive application of the technologies such as field numerical control processing, arc welding robot, intermediate frequency induction internal and external heating and the like provides a new technical route for eliminating the major defects of the inner cavities of the high-temperature and high-pressure steam valves of the same type and provides a method and a way for field maintenance of related equipment.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (5)
1. An on-site repairing method suitable for a pit cavity space is characterized by comprising the following steps:
turning and removing the part of the surface to be processed with the defects;
planning to perform arc welding by using a robot;
heating inside and outside through medium frequency induction;
welding and repairing the part of the surface to be processed by using a robot;
a step of arc welding by a robot, comprising:
an off-line simulation step: establishing a virtual model of the pit cavity in an off-line manner, determining the length, the shape and the posture of a matched welding gun according to the structure of the pit cavity, virtually teaching the movement track and the movement path of the welding gun, and determining that the welding track and the posture are not in conflict with the internal structure of the pit cavity;
parameter transplanting step: the robot is linked with a positioner in a laboratory to simulate the position and the posture of a part of a surface to be processed on site, a working state and a mode which are the same as those of an on-site on-line repair environment are constructed, a whole set of process parameters are obtained through simulation, and the parameters of off-line simulation are transplanted to the site;
a robot three-point teaching step: calculating the circle center through three-point positioning, thereby planning the track of a circle and completing teaching work;
and (3) planning a welding bead and a track: multilayer multi-pass welding is required, and when welding is actually carried out, the multilayer multi-pass welding path planning is completed according to the established space geometric coordinate diagram by the following steps:
1) three-point position finding;
2) calculating a new tool coordinate system according to the height difference and the radius difference of the flange edge of the part of the welding surface and the surface to be processed in the drawing;
3) for multilayer multi-pass welding, determining offset according to the welding thickness of each pass, and performing welding track precision calibration; then, dividing and deviating the track of the circle according to the process requirements, and determining different initial and end welding positions according to the geometric positions to meet the technical requirements of welding joint staggering;
determining the extra height and width of each welding seam according to welding current, wire feeding speed and welding speed parameters through a process test, and further completing the implementation of multilayer welding beads by utilizing a welding offset program, namely determining the position height of the welding bead in the Z direction and determining the relative offset position of the welding bead in the Y direction; inputting Z-direction and Y-direction position deviation values of a subsequent welding pass in the arc welding robot in the whole welding process to realize welding according to a pre-planned track and speed.
2. The method for in situ repair of a cavity space according to claim 1, wherein the turned areas comprise a raw weld overlay material and a weld heat affected zone; after the turning is finished, the optical spectrum inspection is confirmed and the coloring inspection is carried out to ensure that the defects are all cleared.
3. The in-situ remediation method for a cavity space of claim 1, wherein said step of heating inside and outside by medium frequency induction comprises:
for the inner wall heat treatment, an internal heating induction coil is fixed on an L-shaped movable disc, and a heating power supply and a water-cooling cable of the internal heating induction coil are connected; before welding or repairing, the internal heating induction coil is moved to a flange opening of the pit cavity through a lifting table tool, and then enters the cavity of the pit cavity until reaching the position of a surface to be processed;
for the outer wall heat treatment, the flexible air-cooled heating cable is directly wound on the outer wall of the part to which the surface to be processed belongs, the flexible air-cooled heating cable is in a working state from the preheating of the part to which the surface to be processed belongs to the end of the whole welding, and a heat dam is formed on the outer wall of the flexible air-cooled heating cable;
the inner wall and the outer wall are subjected to heat treatment simultaneously, after the preheating temperature is constant, only the inner heating induction coil is withdrawn, and the outer wall is subjected to heat treatment at a constant temperature to ensure the interlayer temperature in the welding or repairing process; and after welding or repairing is finished, the internal heating induction coil enters, and postweld heat treatment is started until the whole heat treatment process is completely finished.
4. The in-situ restoration method suitable for the pit cavity space according to claim 1, wherein the surface to be processed is a sealing surface, and the part to which the surface to be processed belongs is a valve seat.
5. The method for in situ remediation of a pit cavity space of claim 1 further comprising a post-repair inspection step.
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| CN201910407369.7A CN110052777B (en) | 2018-09-30 | 2018-09-30 | On-site repairing method suitable for pit cavity space |
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| CN201811163163.6A CN108971883B (en) | 2018-09-30 | 2018-09-30 | Suitable for cheating the field repairing method of cavity space |
| CN201910407369.7A CN110052777B (en) | 2018-09-30 | 2018-09-30 | On-site repairing method suitable for pit cavity space |
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| CN116175079A (en) * | 2023-03-03 | 2023-05-30 | 中国核电工程有限公司 | Furnace tapping pipe repair system and method |
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Also Published As
| Publication number | Publication date |
|---|---|
| CN110052777A (en) | 2019-07-26 |
| CN108971883B (en) | 2019-11-15 |
| CN108971883A (en) | 2018-12-11 |
| CN110125607A (en) | 2019-08-16 |
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Effective date of registration: 20211008 Address after: 201100 No. 5060, Longwu Road, Minhang District, Shanghai Patentee after: SHANGHAI ELECTRIC POWER Co.,Ltd. WUJING THERMAL POWER PLANT Address before: No. 5060, Longwu Road, Minhang District, Shanghai 200241 Patentee before: SHANGHAI WUJING POWER ENGINEERING Co.,Ltd. Patentee before: SHANGHAI ELECTRIC POWER Co.,Ltd. WUJING THERMAL POWER PLANT |