CN107876355B - Optimization process of strain gauge mounting method - Google Patents
Optimization process of strain gauge mounting method Download PDFInfo
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- CN107876355B CN107876355B CN201711099289.7A CN201711099289A CN107876355B CN 107876355 B CN107876355 B CN 107876355B CN 201711099289 A CN201711099289 A CN 201711099289A CN 107876355 B CN107876355 B CN 107876355B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
- B05D7/50—Multilayers
- B05D7/56—Three layers or more
- B05D7/58—No clear coat specified
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/10—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by other chemical means
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/12—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by mechanical means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
Abstract
The invention discloses an optimization process of a strain gauge mounting method, which comprises the following steps: setting a standard part which is made of the same material as the test piece to be tested; polishing an installation area of the standard component for supplying the variable gauge installation to roughen the surface of the installation area, and cleaning the installation area; spraying active spraying materials on the surface of one side of the standard part layer by layer to form a bonding layer and a pre-coating layer in sequence; spraying the active spray material on the pre-coating to form a final coating; testing the bonding strength of each coating sprayed on the standard part; according to the test result of the bonding strength, optimizing and adjusting the spraying parameters of each coating; and repeating the steps in sequence until the test result of the bonding strength meets a preset process requirement, taking the finally optimized and adjusted spraying parameters of each coating as the spraying parameters of each coating when the strain gauge is installed on the test piece, and curing to obtain the strain gauge installation method.
Description
Technical Field
The invention relates to the field of research and development testing of aircraft engines, in particular to an optimization process of a strain gauge installation method.
Background
In the development process of the existing aircraft engine, the stress measurement of a high-temperature part (test piece) applied to a temperature environment of 600-1000 ℃ mainly depends on a high-temperature strain gauge. The installation area of the test piece is processed, then a prefabricated coating is sprayed on the installation area of the test piece, and then the high-temperature strain gauge is fixedly covered on the prefabricated coating. For the optimized process of the installation method of the strain gauge, the invention patent of China (CN 102191446B) for improving the bonding strength of the substrate and the ceramic coating can be referred, and the bonding strength of the coating is improved mainly by preprocessing processing traces such as dovetail grooves on the surface of a test piece, adjusting the sand blowing process parameters and controlling the thickness of the coating.
However, the prior art, including the above-described optimization process, is directed to test pieces of the type that are primarily ceramic piston rods for hydraulic cylinders. When the test piece is of the type of a turbine blade of an aircraft engine, preprocessing traces such as a dovetail groove on the surface of the test piece of the type can change the stress state of the test piece, and if the existing optimization processing method is not adopted, other installation methods of the test piece which is suitable for a high-temperature environment of more than 600 ℃ do not exist in the prior art.
Disclosure of Invention
It is a primary object of the present invention to overcome at least one of the above-mentioned deficiencies of the prior art and to provide an optimized process for strain gauge mounting that avoids changing the stress state of the test piece surface.
In order to achieve the purpose, the invention adopts the following technical scheme:
according to one aspect of the present invention, there is provided an optimization process of a strain gauge mounting method for optimizing a mounting method of a strain gauge to a test piece, comprising the steps of:
setting a standard part, and setting a standard part which is made of the same material as the test part to be tested;
a grinding and cleaning process of grinding a surface of the standard component to which the supply gauge is attached to roughen the surface of the standard component and cleaning the surface of the standard component;
spraying a bonding layer and a pre-coating layer, and spraying an active spraying material on the surface of the standard component layer by layer to form the bonding layer and the pre-coating layer in sequence;
spraying the final coating, namely spraying the active spraying material on the pre-coating to form the final coating;
testing the bonding strength, namely testing the bonding strength of each coating sprayed on the standard part;
optimizing spraying parameters, and optimizing and adjusting the spraying parameters of each coating according to the test result of the bonding strength; and
and repeating the steps in sequence until the test result of the bonding strength meets a preset process requirement, taking the finally optimized and adjusted spraying parameters of each coating as the spraying parameters of each coating when the strain gauge is installed on the test piece, and curing to obtain the strain gauge installation method.
According to one embodiment of the invention, the surface of the standard is sanded using a sand blasting process.
According to one embodiment of the present invention, the material of the sand grains in the sand blasting process is white corundum or carborundum.
According to one embodiment of the present invention, the grit number in the sand blowing process is less than or equal to 100 mesh.
According to one embodiment of the present invention, the blowing pressure in the blowing process is greater than or equal to 0.5 MPa.
According to one embodiment of the invention, the cleaning of the surface of the standard comprises the following steps:
the method comprises the following steps of (1) carrying out primary cleaning, namely cleaning the surface of a standard part by using a cleaning solution before polishing the standard part, and then blowing the surface of the standard part by using dry compressed gas; and
and cleaning again, namely after polishing the standard part, blowing the surface of the standard part by using dry compressed gas, and cleaning the surface of the standard part by using an active solvent.
According to one embodiment of the invention, the cleaning solution in the primary cleaning is acetone or ethanol, and the cleaning mode is flushing or ultrasonic cleaning.
According to one embodiment of the invention, the cleaning solution in the second cleaning is trichloroethylene, butanone or trichloroethane, and the cleaning mode is flushing or ultrasonic cleaning.
According to one embodiment of the invention, the time interval between the grinding and cleaning process and the spraying of the bonding layer and the pre-coat is less than or equal to 4 hours.
According to one embodiment of the invention, the spray pattern in spraying the bonding layer and the pre-coat is high temperature flame spraying, plasma spraying or low velocity spray system spraying.
According to the technical scheme, the strain gauge mounting method has the advantages and positive effects that the optimization process of the strain gauge mounting method has the following advantages:
according to the optimized process of the mounting method of the strain gauge, provided by the invention, the processes of polishing and cleaning treatment, spraying the bonding layer, pre-coating, spraying the final coating and the like are carried out on the standard component, so that each process except for fixing the strain gauge in the mounting method of the strain gauge can be simulated, and the spraying process parameters of each step are optimized and designed according to the test result of the bonding strength test of each coating of the standard component treated by the processes, thereby realizing the optimization of the mounting method of the strain gauge. Therefore, for a test piece applied to a temperature environment of more than 600 ℃, in particular to a test piece such as a turbine blade in an aircraft engine, the invention can realize the optimization of the mounting method of the strain gauge on the premise of not changing the stress state of the surface of the test piece. Moreover, each simulation process can be iterated repeatedly on the standard component, so that the process parameters can be optimized to the maximum extent, and the success rate of mounting the strain gauge is improved to the maximum extent. In addition, the invention can realize the optimization of a plurality of parameters such as the thickness, the uniformity, the bonding strength and the like of the coating, has strong operability, does not depend on human experience, and is completely based on the measured data.
Drawings
Various objects, features and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, when considered in conjunction with the accompanying drawings. The drawings are merely exemplary of the invention and are not necessarily drawn to scale. In the drawings, like reference characters designate the same or similar parts throughout the different views. Wherein:
FIG. 1 is a process flow diagram illustrating an optimization process for a strain gauge mounting method according to an exemplary embodiment;
FIG. 2 is a partial side view of a standard part of an optimization process of the strain gauge mounting method shown in FIG. 1;
FIG. 3 is a process flow diagram illustrating a strain gage mounting method according to an exemplary embodiment;
fig. 4 is a partial side view of a strain gauge mounted to a test piece according to the strain gauge mounting method shown in fig. 3.
Wherein the reference numerals are as follows:
100. a test piece;
200. a bonding layer;
300. pre-coating;
400. a strain gauge;
410. a pin;
510. a first covercoat;
520. a second overlay coating;
600. final coating;
700. and (4) standard parts.
Detailed Description
Exemplary embodiments that embody features and advantages of the invention are described in detail below. It is to be understood that the invention is capable of other and different embodiments and its several details are capable of modification without departing from the scope of the invention, and that the description and drawings are accordingly to be regarded as illustrative in nature and not as restrictive.
In the following description of various exemplary embodiments of the invention, reference is made to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration various exemplary structures, systems, and steps in which aspects of the invention may be practiced. It is to be understood that other specific arrangements of parts, structures, example devices, systems, and steps may be utilized and structural and functional modifications may be made without departing from the scope of the present invention. Moreover, although the terms "between," "over," "side," and the like may be used in this specification to describe various example features and elements of the invention, these terms are used herein for convenience only, e.g., in accordance with the orientation of the examples described in the figures. Nothing in this specification should be construed as requiring a specific three dimensional orientation of structures in order to fall within the scope of the invention.
Optimized process implementation mode of strain gauge mounting method
Referring to fig. 1, a process flow diagram of an optimization process for a strain gauge mounting method that can embody principles of the present invention is representatively illustrated in fig. 1. In the exemplary embodiment, the optimization process of the strain gauge mounting method provided by the invention is described by taking as an example a mounting method suitable for mounting a high-temperature strain gauge of 600-1000 ℃ on a test piece of an aircraft engine, such as a turbine blade. It will be readily appreciated by those skilled in the art that various modifications, additions, substitutions, deletions or other changes may be made to the embodiments described below to optimize the strain gage mounting method for use in other temperature environments or for strain gage mounting on other types of test pieces, and still fall within the scope of the principles of the optimized strain gage mounting method set forth herein.
As shown in fig. 1, in the present embodiment, the optimization process of the strain gauge mounting method proposed by the present invention mainly includes the steps of grinding and cleaning, spraying the bonding layer and the pre-coating layer, spraying the final coating layer, and the like. Referring to fig. 2, a partial side view of the standard in the above-described optimization process is representatively illustrated in fig. 2. The following describes in detail each step of the optimization process of the strain gauge mounting method according to the present invention with reference to the above drawings.
As shown in fig. 1, in the present embodiment, the present invention proposes an optimization process of a strain gauge mounting method for optimizing a mounting method of a strain gauge (high temperature strain gauge) suitable for 600 ℃ to 1000 ℃ to a test piece such as a turbine blade of an aircraft engine. The optimization process of the strain gauge mounting method mainly comprises the following steps:
setting a standard part, and setting a standard part which is made of the same material as the test part to be tested;
a grinding and cleaning process of grinding a surface of the standard component to which the supply gauge is attached to roughen the surface of the standard component and cleaning the surface of the standard component;
spraying a bonding layer and a pre-coating layer, and spraying an active spraying material on the surface of the standard component layer by layer to form the bonding layer and the pre-coating layer in sequence;
spraying the final coating, namely spraying the active spraying material on the pre-coating to form the final coating;
testing the bonding strength, namely testing the bonding strength of each coating sprayed on the standard part;
optimizing spraying parameters, and optimizing and adjusting the spraying parameters of each coating according to the test result of the bonding strength; and
and repeating the steps in sequence until the test result of the bonding strength meets a preset process requirement, taking the finally optimized and adjusted spraying parameters of each coating as the spraying parameters of each coating when the strain gauge is installed on the test piece, and curing to obtain the strain gauge installation method.
Preferably, for each main step of the optimization process of the strain gauge mounting method described above, the present invention proposes the following specific process or preferred parameters.
In this embodiment, for the step of providing the standard member, the standard member may be made of the same material as the test member, and the shape of the standard member may preferably be circular, that is, a standard disk made of the same material as the test member is made, and the size of the standard disk corresponds to (for example, is equal to or slightly larger than) the size of the mounting area (the portion to be mounted with the strain gauge and the high-temperature wire thereof) required by the real test member to mount the strain gauge.
Further, in the present embodiment, the diameter, thickness and parallelism of the standard disk can be optimally designed, and the edge of the standard disk is preferably in a structure that maintains a sharp angle.
In this embodiment, for the polishing step, a sand blasting process may be adopted, that is, a high hardness material may be used to perform sand blasting polishing on the surface of the standard disk.
Specifically, in the present embodiment, the hardness of the sand material blown with sand is preferably higher than the hardness of the standard disk surface, for example, white corundum or carborundum. The sand blown into the sand is preferably coarse sand, and more preferably coarse sand having a grit of 100 mesh or less. The blowing pressure is preferably 0.5MPa or more. And finally, the roughness of the surface of the standard disc can be controlled by controlling the sand blowing angle. If the surface of the standard disk is observed under a microscope, the surface is in a state that a fresh metal surface is exposed (the standard disk is made of metal).
In this embodiment, the step of the cleaning process may further include the steps of:
the method comprises the following steps of (1) carrying out primary cleaning, namely cleaning the surface of a standard part by using a cleaning solution before polishing the standard part, and then blowing the surface of the standard part by using dry compressed gas; and
and cleaning again, namely after polishing the standard part, blowing the surface of the standard part by using dry compressed gas, and cleaning the surface of the standard part by using an active solvent.
Specifically, in the present embodiment, for the preliminary cleaning step, a medium that is relatively easily dissolved by organic substances, such as acetone and ethanol, may be preferably used as the cleaning liquid, and the standard disk surface may be cleaned by rinsing or ultrasonic cleaning, so as to achieve the function of removing impurities on the standard disk surface. In addition, the standard disk surface may be purged with dry clean compressed air.
In the present embodiment, for the step of re-cleaning, a medium capable of improving metal activity, such as trichloroethylene, butanone, or trichloroethane, may be preferably used as the cleaning liquid, and the standard disk surface may be cleaned by rinsing or ultrasonic cleaning, so as to improve the metal activity of the standard disk surface. In addition, the surface of the standard disk can be blown by dry clean compressed air.
In the present embodiment, the time interval between the step of spraying the bonding layer and the pre-coating layer and the step of the grinding and cleaning treatment is preferably less than or equal to 4 hours.
In this embodiment, for the step of spraying the bonding layer, a spraying device (e.g., a high-temperature spraying device such as high-temperature flame spraying, plasma spraying, and low-speed spraying system) may be used to perform high-temperature spraying on the surface of the standard disk, and the process parameters during the spraying process may be adjusted and optimized according to the test result of the later bonding strength test. The process parameters may include, among other things, at least spray distance, spray angle, gas phase parameters (e.g., oxygen, acetylene, compressed air pressure, flow), effective duration of spray, and thickness and uniformity of each coating (including bond coat, pre-coat, and final coat).
Specifically, in the present embodiment, when the bonding layer is sprayed by high-temperature spraying, the active spraying material of the bonding layer may mainly include high-purity alumina or other active powder capable of enhancing the bonding force (other coating layers may also be selected from such active spraying materials). For the control of the sprayed thickness of the bonding layer, it is preferable that the bonding layer just covers the sand blasted surface of the standard disc when observed under a microscope, and there is no build-up of coating particles of the bonding layer.
In this embodiment, for the step of spraying the pre-coat, the spraying can be continued by using the same material and spraying manner after the step of spraying the bonding layer, that is, the pre-coat is sprayed on the bonding layer. The thickness and uniformity of the pre-coat should be controlled during the spraying process. In addition, the thickness of the pre-coating can be controlled according to the insulating strength of the coating to metal, and the pre-coating can be made as thin as possible under the condition of meeting the insulating strength.
In the present embodiment, for the step of spraying the final coating layer, which is to spray the final coating layer on the pre-coating layer, the spraying of the final coating layer can refer to the spraying parameters of the bonding layer, the pre-coating layer or the cover coating layer. After spraying the final coating, the sprayed final coating may be post-sprayed, i.e., the surface of the final coating may be smoothed, and the corners and edges of the final coating may be smoothed.
In this embodiment, for the step of testing the bonding strength, the standard disk after spraying the above-mentioned coatings can be fixed on the tool, and can be preferably bonded on the tool by an adhesive with higher bonding strength. And then, placing the standard disk and the tool on a tensile testing machine for tensile breaking, thereby measuring the bonding strength of each coating sprayed on the standard disk.
In the present embodiment, the step of optimizing the spraying parameters is to optimize and adjust the spraying parameters of each coating layer based on the test result of the bonding strength of each coating layer on the standard disk measured in the bonding strength test. Therefore, through comparison of multiple groups of calibration tests, the final result of the bonding strength test optimizes the sand blowing process parameters and the spraying process parameters, and the optimal sand blowing and high-temperature spraying parameters suitable for installing the high-temperature strain gauge of the material can be obtained. The intermediate measurement results of sand blowing and spraying and the optimized parameters are fixed through a bonding strength test and can be used for real test piece spraying quantitative control parameters. And finally, optimizing and adjusting the spraying parameters of each coating as the spraying parameters of each coating when the strain gauge is installed on a test piece, and curing the spraying parameters into the strain gauge installation method.
In the optimization process of the strain gauge mounting method provided by the invention, the coating structure formed on the standard part 700 by the above process and method can be roughly described with reference to fig. 2, a bonding layer 200 is formed on the surface of the standard part 700 (a pre-coating layer can be further added in the repeated iterative optimization process), and a final coating layer 600 is sprayed and covered on the bonding layer 200 (or the pre-coating layer in the repeated iterative optimization process).
In summary, the optimized process of the strain gauge mounting method provided by the invention can simulate various processes except for fixing the strain gauge in the strain gauge mounting method by applying the processes of polishing and cleaning treatment, spraying the bonding layer, pre-coating, spraying the final coating and the like on the standard part, so that the spraying process parameters of various steps are optimized and designed according to the test result of the bonding strength test of various coatings of the standard part treated by the processes, thereby realizing the optimization of the strain gauge mounting method. Therefore, for a test piece applied to a temperature environment of more than 600 ℃, in particular to a test piece such as a turbine blade in an aircraft engine, the invention can realize the optimization of the mounting method of the strain gauge on the premise of not changing the stress state of the surface of the test piece. Moreover, each simulation process can be iterated repeatedly on the standard component, so that the process parameters can be optimized to the maximum extent, and the success rate of mounting the strain gauge is improved to the maximum extent. In addition, the invention can realize the optimization of a plurality of parameters such as the thickness, the uniformity, the bonding strength and the like of the coating, has strong operability, does not depend on human experience, and is completely based on the measured data.
Method for mounting strain gauge
Referring to fig. 3, a process flow diagram of a method of mounting a strain gauge is representatively illustrated in fig. 3. In the exemplary embodiment, the method for mounting the strain gauge according to the present invention is described by taking as an example a method for mounting a high temperature strain gauge suitable for use at 600 ℃ to 1000 ℃ to a test piece such as a turbine blade of an aircraft engine. It will be readily appreciated by those skilled in the art that various modifications, additions, substitutions, deletions or other changes may be made to the embodiments described below in order to adapt the strain gage mounting method to other temperature environments or to mount strain gages on other types of test pieces, and still fall within the scope of the principles of the strain gage mounting method as set forth in the present disclosure.
As shown in fig. 3, the method for mounting a strain gauge provided by the present invention mainly includes a test piece surface pretreatment, a strain gauge fixing and coating implementation process, and a wire connection process. The surface pretreatment of the test piece can comprise polishing treatment and cleaning treatment, and the strain gauge fixing and coating implementation process can comprise fixing the strain gauge and spraying each coating. In addition, in order to select a better safety region, the strain gauge mounting method provided by the invention can further comprise a process of selecting a mounting region and calculating the peel strength of the coating and comparing the peel strength with the preset bonding strength. The following describes in detail the main process steps of the strain gauge mounting method.
As shown in fig. 3, in this embodiment, the method for mounting a strain gauge according to the present invention mainly includes polishing, cleaning, spraying a bonding layer, spraying a pre-coating layer, fixing the strain gauge, spraying an overlay coating layer, spraying a final coating layer, and connecting high-temperature wires. Referring to fig. 4, a partial side view of a strain gage mounted to a test piece according to the above-described strain gage mounting method is representatively illustrated in fig. 4. The steps of the method for mounting a strain gauge according to the present invention will be described in detail below with reference to the drawings.
As shown in fig. 3, in the present embodiment, the present invention proposes a method of mounting a strain gauge (high temperature strain gauge) suitable for use at 600 ℃ to 1000 ℃ to a test piece such as a turbine blade of an aircraft engine. The installation method of the strain gauge mainly comprises the following steps:
polishing the installation area of the supply variable meter installation of the test piece to roughen the surface of the installation area;
cleaning, namely cleaning the installation area of the test piece;
spraying a bonding layer, namely spraying an active spraying material on the mounting area of the test piece in a high-temperature spraying manner to form the bonding layer;
spraying a pre-coating, namely spraying an active spraying material on the bonding layer in a high-temperature spraying manner to form the pre-coating;
fixing a strain gauge, namely fixing the strain gauge on the precoating, and attaching one surface of the strain gauge to the precoating;
spraying a covering coating, namely spraying an active spraying material on the rest surfaces of the strain gauge and the part of the pre-coating layer which is not covered by the strain gauge in a high-temperature spraying manner to form the covering coating;
spraying the final coating, namely spraying the active spraying material on the covering coating in a high-temperature spraying manner to form the final coating; and
and connecting the pins of the strain gauge with the high-temperature wires.
Preferably, for each main step of the above-described method of mounting the strain gauges, the present invention proposes the following specific mounting operation method or preferred parameters.
In this embodiment, for the polishing step, a sand blasting process may be adopted, that is, a high-hardness material may be used to perform sand blasting and polishing on the portion of the surface of the test piece where the strain gauge and the high-temperature lead thereof are to be mounted.
Specifically, in the present embodiment, the hardness of the sand material blown with sand is preferably higher than the hardness of the surface of the test piece, and is, for example, white corundum or carborundum. The sand blown into the sand is preferably coarse sand, and more preferably coarse sand having a grit of 100 mesh or less. The blowing pressure is preferably 0.5MPa or more. And finally, the roughness of the surface of the test piece can be controlled by controlling the sand blowing angle. When the surface of the test piece is observed under a microscope, a fresh metal surface (the test piece is made of a metal material) is exposed. Moreover, for the selection of each parameter in the sand blowing process, the test result of the bonding strength test in the above optimization process can be combined for reasonable fine tuning, which is not described herein again.
In this embodiment, the step of the cleaning process may further include the steps of:
the method comprises the following steps of (1) performing primary cleaning, namely cleaning an installation area by using cleaning liquid before polishing treatment, and then purging the installation area by using dry compressed gas; and
and cleaning again, namely after polishing treatment, purging the mounting area by using dry compressed gas, and cleaning the mounting area by using an active solvent.
Specifically, in the present embodiment, for the primary cleaning step, a medium that is relatively easily soluble in organic substances, such as acetone and ethanol, may be preferably used as the cleaning solution, and the installation area may be cleaned by rinsing or ultrasonic cleaning, so as to remove the surface impurities. In addition, the installation area can be purged by using dry clean compressed air.
In the present embodiment, for the step of re-cleaning, a medium capable of improving metal activity, such as trichloroethylene, butanone, or trichloroethane, may be preferably used as the cleaning liquid, and the mounting region may be cleaned by rinsing or ultrasonic cleaning, thereby improving the metal activity of the surface of the test piece. In addition, the installation area can be purged by using dry and clean compressed air.
In this embodiment, for the step of spraying the bonding layer, after a reserved area for mounting the strain gauge and routing pins thereof is reserved on the surface of the test piece, the periphery of the reserved area is protected by adhering high-temperature adhesive tape. And then, high-temperature spraying is carried out on the surface of the test piece by adopting a spraying device (such as high-temperature flame spraying, plasma spraying, a low-speed spraying system and other high-temperature spraying devices), and the spraying distance, the spraying angle, gas-phase parameters (such as the pressure and the flow of oxygen, acetylene and compressed air) and the spraying thickness of the bonding layer are controlled in the spraying process.
Specifically, in the present embodiment, for the step of spraying the bonding layer by means of high-temperature spraying, the active spraying material of the bonding layer may mainly include high-purity alumina or other active spraying material capable of enhancing the bonding force. For control of the sprayed thickness of the bonding layer, it is preferred that the bonding layer just covers the grit blasted surface of the test piece when viewed under a microscope, preferably covers about 80% to 90% of the mounting area, and there is no build-up of coating particles of the bonding layer.
In addition, after the spraying of the bonding layer is stopped, the sprayed particles with poor bonding force and accumulated on the bonding layer can be removed, particularly in the areas of arcs, guide corners and the like of the test piece. Air cooling and intermittent spraying are additionally added to the test piece with the thin thickness to prevent the test piece from overheating, and the protection temperature is determined by specifically combining the material of the test piece.
It should be noted that, for the step of spraying the bonding layer, the step is actually a design obtained through repeated iterative optimization in the optimization process of the mounting method of the strain gauge, that is, the spraying of the bonding layer can greatly improve the bonding effect and success rate of mounting the strain gauge. However, in other embodiments, the step of spraying the bonding layer, i.e., spraying the pre-coating layer directly on the mounting region, may not be performed, and is not limited to the embodiment.
In this embodiment, for the step of spraying the pre-coat, the spraying can be continued by using the same material and spraying manner after the step of spraying the bonding layer, that is, the pre-coat is sprayed on the bonding layer. The thickness and uniformity of the pre-coat should be controlled during the spraying process, and preferably the pre-coat is sprayed in multiple passes if the arc transition region of the test piece is encountered. In addition, the thickness of the pre-coating can be controlled according to the insulating strength of the coating to metal, and the pre-coating can be made as thin as possible under the condition of meeting the insulating strength.
In the present embodiment, the fixing of the strain gauge and the spraying of the cover coat belong to the related steps, and the step of fixing the strain gauge and the spraying of the cover coat may specifically include the following steps:
attaching the strain gauge on the pre-coating;
a plurality of high-temperature adhesive tapes are transversely stuck on the strain gauge and two ends of each high-temperature adhesive tape are stuck on the pre-coating, the high-temperature adhesive tapes are arranged in parallel at intervals, and a gap is formed between every two adjacent high-temperature adhesive tapes;
spraying to form a first covering coating on each gap;
removing the high-temperature adhesive tape;
sticking a high-temperature adhesive tape again on the first cover coat corresponding to each gap;
spraying and forming a second covering coating on each gap formed between the re-pasted high-temperature adhesive tapes; and
removing the high-temperature adhesive tape which is pasted again;
wherein the first covercoat and the second covercoat together form a complete covercoat.
The step of placing the strain gauge on the precoat and adhering the strain gauge to the precoat by using the high-temperature adhesive tape is the step of fixing the strain gauge in the embodiment. Meanwhile, the high-temperature adhesive tapes which are adhered at the moment are mutually parallel and spaced and cross the strain gauge, so that the step of spraying the covering coating can be combined with the spraying of the first covering coating and the subsequent steps.
Specifically, in the present embodiment, for the step of fixing the strain gauge, a preferred position for fixing the strain gauge on the test piece can be obtained according to the finite element calculation result, and the strain gauge is fixed at the position (processed in the previous steps), and the wire grid direction and the pin routing direction are controlled to ensure the insulation between the strain gauge and the test piece. In addition, since the strain gauge applied to a high temperature of 600 to 1000 ℃ is a strain gauge structure having a temporary frame and no substrate, the strain gauge should be as close as possible to the pre-coating layer when fixing the strain gauge using a high temperature tape.
Further, in this embodiment, for the step of spraying the covercoat, both sprayings of the covercoat can refer to the above-described spray process and parameters of the bond coat or the pre-coat.
The spraying step of the first covering coating is to spray the surface of the strain gauge exposed at the gap between the high-temperature adhesive tapes after the high-temperature adhesive tapes are pasted for the first time, and preferably adopts a high-temperature spraying mode, and the formed first covering coating covers approximately 80-90% of the depth of the gap. The first covercoat is disposed in a plurality of bands across the strain gage and spaced parallel to each other. Accordingly, even if the high-temperature adhesive tape applied for the first time is peeled off, the first cover coat layer can firmly attach the strain gauge to the pre-coat layer. The spraying step of the second cover coating is to spray the surface of the strain gauge exposed at the gap of the first cover coatings (i.e. the high-temperature adhesive tape pasted for the second time) after spraying the first cover coating, tearing off the high-temperature adhesive tape pasted for the first time and pasting the high-temperature adhesive tape on each first cover coating, and the high-temperature spraying mode can also be preferably adopted, and the formed second cover coating also covers approximately 80% -90% of the depth of the gap. In addition, the width of the high-temperature adhesive tape adhered on the first covering coating is less than or equal to the width of the second covering coating on which the high-temperature adhesive tape is adhered. The second cover coating is also distributed in a plurality of bands which cross the strain gauge and are spaced in parallel with each other, and each second cover coating is spaced from each first cover coating. And removing the high-temperature adhesive tape which is pasted again, wherein each first covering coating and each second covering coating jointly form a complete covering coating covering the surface (including the pins) of the strain gauge.
In the spraying process of the first covering coating and the second covering coating, the high-temperature adhesive tape which is pasted twice actually has the functions of primarily fixing the strain gauge and covering the first covering coating respectively, and belongs to a part which is removed after being used. Accordingly, in this embodiment, the strain gauge is actually a complete overlay coating comprised of the first and second overlay coatings affixed to the pre-coat. In other embodiments, the strain gauge may be fixed in other manners to adapt to the application environment above 600 ℃, which is not limited to this embodiment.
In the present embodiment, for the step of spraying the final coating layer, which is to spray and form the final coating layer on the cover coating layer, the spraying process and parameters of the bonding layer, the pre-coating layer or the cover coating layer can be referred to for the spraying of the final coating layer. The final coating formed by spraying completely covers the first and second covercoats, i.e., forms a complete final coating over the bent covercoat.
It should be noted that, for the selection of the process parameters of each coating in the coating spraying steps, the test results of the bonding strength test in the optimization process can be referred to for reasonable fine tuning, which is not described herein again.
In this embodiment, when the width of the high temperature adhesive tape adhered to the first cover coat is smaller than the width of the second cover coat, the second cover coat formed by spraying may form a coating overlap at the edge position corresponding to the adjacent first cover coat, thereby causing the cover coat to form a protrusion at each adjacent position of the first cover coat and the second cover coat, and when the final coating is sprayed on the cover coat, the surface of the final coating may present a corresponding protrusion. Therefore, after spraying the final coating, the sprayed final coating may be subjected to post-spray treatment, i.e., smoothing of the surface of the final coating and smoothing of the corner portions and edge portions of the final coating.
In the step of forming each coating by spraying, the formed coatings are all compact coatings, and the coatings are burnt by acetylene flame or other high-temperature media to fully release residual stress, so that the consistency and the stability of the coatings are greatly improved compared with the prior art, and the thermal shock resistance effect is better than that of the prior art.
In the embodiment, for the step of high-temperature wire connection, the pins of the strain gauge can be tightly wound on the high-temperature wire, the number of winding turns of the pins can be preferably 9-10, and a stress release ring is left. The high-temperature lead is connected with the strain gauge pin by spot welding, and the spot welding energy and pulse width index are determined according to the material characteristics and the thickness of the lead. In addition, for the spot welding process, it should be ensured that the spot welding is firm and stable, and it is preferable that the strain gauge pin is melted to some extent but not fused.
It should be noted herein that the method of mounting the strain gauges shown in the drawings and described in this specification is only one example of the many types of mounting methods that can employ the principles of the present invention. It should be clearly understood that the principles of the present invention are in no way limited to any of the details of the installation method or any of the steps of the installation method shown in the drawings or described in this specification.
For example, in the present embodiment, the method for mounting a strain gauge according to the present invention may further include:
selecting an installation area, namely selecting the installation area of the strain gauge on the test piece by using a finite element calculation mode before polishing and cleaning; and
calculating the peel strength, and calculating the peel strength of the coating on the selected mounting area; when the peeling strength is less than or equal to a preset bonding strength of the coating, polishing and cleaning are carried out on the selected mounting area; and when the peeling strength is larger than the preset bonding strength of the coating, repeating the step of selecting the mounting area, and selecting a new mounting area.
In the present embodiment, the step of selecting the mounting region is to select test points on the test piece by using a finite element calculation or the like according to the working condition of the test piece. Specifically, taking a gas blade or a power turbine blade as an example of a test piece, vibration modes of each order of the test piece can be calculated, and a position of the test piece sensitive to dynamic stress response of key orders of modes is found, wherein the position is generally a region with a larger dynamic stress level in the former three orders of modes. At the moment, working conditions such as rotating speed, temperature, pneumatic load and the like are comprehensively considered, and particularly, the generated excitation frequency is related to the rotating speed and is closer to the modal frequency under the influence of the structure of the rotor of the test piece. The test points determined according to the method are not suitable for having larger stress concentration or stress gradient, namely, the test points cannot have larger change along with the position degree so as to avoid larger value difference caused by the position deviation of different blade patches. Meanwhile, the strain gauge is not suitable to be too close to the edge of the test piece within 2mm, so that the strain gauge cannot be fixed. Further, the mounting direction of the strain gauge can be determined from the direction in which the deformation is large.
In the present embodiment, the step of calculating the peel strength is to calculate the peel strength of the coating at the rotation speed and the aerodynamic load. The influence of centrifugal force and airflow scouring force on the bonding strength of the coating can be mainly considered. The stripping effect cannot exceed the optimal bonding strength of the coating, otherwise, the step of selecting the mounting area is returned, and the position of the selected test point is readjusted.
Through the above steps and processes, the strain gauge 400 is mounted on the test piece 100 by the strain gauge mounting method according to the present invention, the structure is roughly as shown in fig. 4, the bonding layer 200 and the pre-coating layer 300 are sequentially formed on the surface (substrate) of the test piece 100, the first covercoating layer 510 and the second covercoating layer 520 are alternately arranged to form a complete covercoating layer, and the strain gauge 400 is fixed on the pre-coating layer 300 through the covercoating layer, and the final coating layer 600 is sprayed and covered on the covercoating layer.
In summary, the mounting method of the strain gauge provided by the invention can realize the mounting of the strain gauge which is suitable for the high-temperature environment above 600 ℃ through the steps of polishing, cleaning, spraying the bonding layer, spraying the pre-coating, fixing the strain gauge, spraying the covering coating, spraying the final coating, connecting the high-temperature lead and the like. Moreover, the strain gauge installed by the installation method of the strain gauge provided by the invention has the advantages of higher success rate in the installation process, strong operability and better bonding strength of each coating. Moreover, each coating formed by the steps belongs to a compact coating, the consistency and the stability of the coating are greatly improved compared with the prior art, and the thermal shock resistance effect is obviously better than that of the prior art. In addition, the invention can realize the optimization of a plurality of parameters such as the thickness, the uniformity, the bonding strength and the like of the coating, has strong operability, does not depend on human experience, and is completely based on the measured data.
It should be noted that, in the above exemplary description of the optimized process of the strain gauge mounting method, the steps of performing the surface preparation (including at least the cleaning and polishing treatments) and each coating (including at least the spraying of the bonding layer, the pre-coating layer, and the final coating layer) on the standard member are respectively the same as those of each corresponding step of the mounting method of the strain gauge on the real test member, and the step of fixing the strain gauge in the mounting method of the strain gauge is not necessarily performed.
The above-described optimization process of the strain gauge mounting method is an exemplary description based on the strain gauge mounting method proposed by the present invention. In other embodiments, the optimization process of the strain gauge mounting method provided by the invention can also be applied to the optimization of other types of strain gauge mounting methods. For example, for the existing installation method for sticking the strain gauge by using the inorganic glue, the optimized process provided by the invention can be utilized to implement each step of the existing installation method for the strain gauge based on the inorganic glue on the standard part, and the bonding strength of each coating or glue layer sprayed or bonded in the existing installation method is tested through the bonding strength test, so that the process parameters of each step in the installation method are optimized and adjusted by referring to the test result, the installation success rate is improved, or the optimal installation effect is achieved.
Exemplary embodiments of the optimized process of the strain gauge mounting method proposed by the present invention are described and/or illustrated in detail above. Embodiments of the invention are not limited to the specific embodiments described herein, but rather, components and/or steps of each embodiment may be utilized independently and separately from other components and/or steps described herein. Each component and/or step of one embodiment can also be used in combination with other components and/or steps of other embodiments. When introducing elements/components/etc. described and/or illustrated herein, the articles "a," "an," and "the" are intended to mean that there are one or more of the elements/components/etc. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements/components/etc. other than the listed elements/components/etc. Furthermore, the terms "first" and "second" and the like in the claims and the description are used merely as labels, and are not numerical limitations of their objects.
While the present invention has been described in terms of various specific embodiments with respect to optimized processes for strain gage mounting, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
Claims (10)
1. An optimization process of a strain gauge mounting method for optimizing a mounting method of a strain gauge to a test piece, characterized by comprising the steps of:
setting a standard part, and setting a standard part which is made of the same material as the test part to be tested;
a grinding and cleaning process of grinding a surface of the standard member to which the supply gauge is attached, roughening the surface, and cleaning the surface;
spraying a bonding layer and a pre-coating layer, and spraying an active spraying material on the surface of the standard component layer by layer to form the bonding layer and the pre-coating layer in sequence;
spraying the final coating, namely spraying the active spraying material on the pre-coating to form the final coating;
testing the bonding strength, namely testing the bonding strength of each coating sprayed on the standard part;
optimizing spraying parameters, and optimizing and adjusting the spraying parameters of each coating according to the test result of the bonding strength; and
and repeating the steps in sequence until the test result of the bonding strength meets a preset process requirement, taking the finally optimized and adjusted spraying parameters of each coating as the spraying parameters of each coating when the strain gauge is installed on the test piece, and curing to obtain the strain gauge installation method.
2. The process of optimizing the strain gauge mounting method of claim 1 wherein the grinding of the surface of the master part is by a sand blasting process.
3. The optimized process for the strain gauge mounting method according to claim 2, wherein the sand material in the sand blowing process is white corundum or carborundum.
4. The optimized process of strain gauge mounting method of claim 2, wherein the grit number in the sand blowing process is less than or equal to 100 mesh.
5. The optimized process of the strain gauge mounting method according to claim 2, wherein the sand blowing pressure in the sand blowing process is greater than or equal to 0.5 MPa.
6. The process of optimizing the strain gauge mounting method of claim 1, wherein the cleaning of the surface of the standard part comprises the steps of:
the method comprises the following steps of (1) carrying out primary cleaning, namely cleaning the surface of a standard part by using a cleaning solution before polishing the standard part, and then blowing the surface of the standard part by using dry compressed gas; and
and cleaning again, namely after polishing the standard part, blowing the surface of the standard part by using dry compressed gas, and cleaning the surface of the standard part by using an active solvent.
7. The optimization process of the strain gauge mounting method according to claim 6, wherein the cleaning solution in the primary cleaning is acetone or ethanol, and the cleaning mode is flushing or ultrasonic cleaning.
8. The optimized process for the strain gauge mounting method according to claim 6, wherein the cleaning solution in the secondary cleaning is trichloroethylene, butanone or trichloroethane, and the cleaning mode is flushing or ultrasonic cleaning.
9. The process of optimizing a strain gauge mounting method according to claim 1, wherein the time interval between the grinding and cleaning process and the spraying of the bonding layer and the pre-coating is less than or equal to 4 hours.
10. The process of optimizing the strain gage mounting method of claim 1 wherein the spray pattern in the spray bond layer and pre-coat is high temperature flame spray, plasma spray or low velocity spray system spray.
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| CN108747074B (en) * | 2018-06-04 | 2020-12-01 | 中国航发沈阳发动机研究所 | Mounting structure and mounting method for micro welding spot on high-speed rotating part |
| CN109916293B (en) * | 2019-03-20 | 2020-08-04 | 中国航发湖南动力机械研究所 | Installation process of strain gauge |
| CN110426208B (en) * | 2019-08-13 | 2021-06-22 | 中国航发贵阳发动机设计研究所 | High temperature strainometer mounting process reliability verification device |
| CN112050980B (en) * | 2020-08-21 | 2022-04-12 | 绍兴文理学院元培学院 | Torque measuring instrument based on strain gauge |
| CN112593226A (en) * | 2020-12-07 | 2021-04-02 | 中国航空工业集团公司北京长城计量测试技术研究所 | Method for improving coating bonding strength in spraying installation of optical fiber sensor |
| CN115122243A (en) * | 2022-07-25 | 2022-09-30 | 西门子燃气轮机部件(江苏)有限公司 | Coating thickness removing method with controllable coating thickness |
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| EP0948737A1 (en) * | 1997-10-24 | 1999-10-13 | Siemens Aktiengesellschaft | Electric resistor and a mechanical electrical transformer produced with said electric resistor |
| CN202599331U (en) * | 2011-09-30 | 2012-12-12 | 梁昌锐 | Resistance strain gage-used UV glue cover surface and manual/automatic glue spraying and curing system thereof |
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