High-temperature-resistant intelligent bolt and pre-tightening force measuring method thereof

Abstract

The invention belongs to the field of aero-engine connecting pieces, and particularly relates to a high-temperature-resistant intelligent bolt and a pre-tightening force measuring method thereof. The high-temperature-resistant intelligent bolt comprises a bolt base body, and an AlN plating layer, a Cr plating layer, an Ag / Cr plating layer and an Ag plating layer are sequentially generated on the bolt head of the bolt base body in a high-temperature sputtering mode. According to the high-temperature-resistant intelligent bolt, the structural characteristics of an original connecting bolt are not damaged, the problem that the intelligent bolt cannot resist high temperature can be solved, the intelligent bolt does not generate high-temperature failure in the service process of an aero-engine, the structure is not damaged after the aero-engine goes through a high-temperature environment, and the risk of generating redundant materials is avoided; and the device still has a pre-tightening force measuring function after high temperature.

Description

Technical Field

[0001] The present application belongs to the field of aero-engine connectors, and in particular relates to a high-temperature resistant intelligent bolt and a method for measuring its preload. Background Art

[0002] A large number of connecting bolts are used in various parts of aircraft engines, but the use status of the connecting bolts cannot be effectively controlled. At present, the smart bolts used in the fields of automobiles, wind power, etc. are mostly used in room temperature environments, which cannot meet the use requirements of aircraft engines in high temperature environments. The sputtering type smart bolts produced by the German Intelifist company can only meet the high temperature use requirements of 320°C. When the temperature exceeds 320°C, the smart bolts lose the ability to measure the preload force and fail. They also cannot meet the precise measurement requirements of the preload force of the connecting bolts throughout the life cycle of the aircraft engine. Although the ordinary connecting bolt preload force measurement method has been verified in the laboratory, the measurement deviation is large, far exceeding the allowable measurement deviation in engineering, and cannot be used in engineering.

[0003] The smart bolts in the prior art include patch-type smart bolts, ordinary sputtering-type smart bolts, bolt cylinder-attached strain gauge-type smart bolts, or bolt center-hole pre-embedded sensor-type smart bolts, etc. Among them, the patch-type smart bolt is to stick the ultrasonic sensor to the bolt measurement end through a coupling agent, so that the connecting bolt becomes a smart bolt with ultrasonic preload measurement function. The preparation and cost of the smart bolt are low, but due to the presence of the coupling agent, the shelf life of the smart bolt is short. In a high-temperature environment, the coupling agent fails and there is a risk of generating excess. Ordinary sputtering-type smart bolts use sputtering technology, which is technically difficult and costly. They have a long shelf life and high reliability, but they still cannot solve the high temperature resistance requirements of smart bolts. Smart bolts with strain gauges on the bolt cylinder or pre-embedded sensors in the bolt center hole damage the structure of the original connecting bolts and cannot be used in engineering.

[0004] Therefore, it is desired to have a technical solution to overcome or at least alleviate at least one of the above-mentioned defects of the prior art. Summary of the invention

[0005] The purpose of the present application is to provide a high temperature resistant intelligent bolt and a method for measuring its preload force to solve at least one problem existing in the prior art.

[0006] The technical solution of this application is:

[0007] The first aspect of the present application provides a high temperature resistant smart bolt, comprising:

[0008] A bolt matrix, on the bolt head of the bolt matrix, an AlN coating, a Cr coating, an Ag / Cr coating and an Ag coating are sequentially formed by high-temperature sputtering.

[0009] In at least one embodiment of the present application, the thickness of the AlN coating is 0.5 to 1.5 microns.

[0010] In at least one embodiment of the present application, the thickness of the Cr coating is 2 to 3 microns.

[0011] In at least one embodiment of the present application, the Ag / Cr coating includes Ag layers and Cr layers that are alternately arranged, and the thickness of the Ag / Cr coating is 3 to 5 micrometers.

[0012] In at least one embodiment of the present application, the thickness of the Ag coating is 1 to 2 microns.

[0013] A second aspect of the present application provides a method for measuring the preload force of a high-temperature resistant smart bolt, based on the high-temperature resistant smart bolt as described above, comprising:

[0014] Step 1, arranging ultrasonic generators on both sides of the AlN coating of the high temperature resistant smart bolt;

[0015] Step 2: calibrate the high temperature resistant smart bolt to obtain a relationship curve between ultrasonic echo time difference and preload force;

[0016] Step 3:

[0017] Before installing the high temperature resistant smart bolt, a pulse voltage is applied to the high temperature resistant smart bolt by the ultrasonic generator to form an ultrasonic signal, and the ultrasonic echo time T0 is measured;

[0018] After the high temperature resistant smart bolt is installed, a pulse voltage is applied to the high temperature resistant smart bolt through the ultrasonic generator to form an ultrasonic signal, and the ultrasonic echo time T1 is measured;

[0019] Step 4: Calculate the ultrasonic echo time difference T1-T0 before and after the installation of the high temperature resistant smart bolt, and obtain the preload force of the high temperature resistant smart bolt according to the relationship curve between the ultrasonic echo time difference and the preload force.

[0020] The invention has at least the following beneficial technical effects:

[0021] The high-temperature resistant smart bolt of the present application does not destroy the structural characteristics of the original connecting bolts, and can solve the problem that the smart bolts cannot withstand high temperatures. The smart bolts will not fail at high temperatures during the service of aircraft engines, and their structure will not be damaged after experiencing a high-temperature environment. There is no risk of generating excess material, and they still have a preload measurement function after experiencing high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of a high temperature resistant smart bolt according to one embodiment of the present application.

[0023] in:

[0024] 1-bolt substrate; 2-AlN coating; 3-Cr coating; 4-Ag / Cr coating; 5-Ag coating. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the embodiment of this application will be described in more detail below in conjunction with the drawings in the embodiment of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of them. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be construed as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.

[0026] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present application.

[0027] The following is combined with Figure 1 This application is described in further detail.

[0028] The first aspect of the present application provides a high-temperature resistant smart bolt, comprising: a bolt base 1, an AlN coating 2, a Cr coating 3, an Ag / Cr coating 4 and an Ag coating 5 are sequentially generated on the bolt head of the bolt base 1 by high-temperature sputtering.

[0029] The high-temperature resistant smart bolt of the present application generates an AlN coating 2 on a bolt base 1 by high-temperature sputtering. The AlN coating is an electrical insulator and acts as a capacitive insulating layer between the bolt base 1 and the conductive layer formed by the Cr coating 3, the Ag / Cr coating 4, and the Ag coating 5, and is used to excite ultrasonic signals.

[0030] In one embodiment of the present application, the thickness of the AlN coating 1 is 0.5 to 1.5 microns, the thickness of the Cr coating 2 is 2 to 3 microns, the Ag / Cr coating 3 includes an alternately arranged Ag layer and a Cr layer, the thickness of the Ag / Cr coating 4 is 3 to 5 microns, and the thickness of the Ag coating 5 is 1 to 2 microns. The coating thickness range may need to be adjusted according to specific circumstances in actual applications. When selecting the coating thickness, factors such as the use environment, performance requirements, cost budget, and processing difficulty should be fully considered to ensure the performance and reliability of the smart bolt; at the same time, attention should also be paid to the uniformity and adhesion of the coating to ensure that the coating can effectively protect the bolt for a long time.

[0031] In the high temperature resistant smart bolt of the present application, the Cr coating 3 and the Ag / Cr coating 4 are adhesive layers, which are mainly used to enhance the bonding strength between the AlN coating 2 and the Ag coating 5, and prevent the Ag coating 5 from falling off the smart bolt. The Ag coating 5 is a high temperature protective layer, which can protect the AlN coating 2 from being oxidized under high temperature conditions, so that the smart bolt still maintains the preload measurement characteristics after experiencing high temperature.

[0032] Based on the above-mentioned high temperature resistant smart bolt, the second aspect of the present application provides a method for measuring the preload force of a high temperature resistant smart bolt, comprising:

[0033] Step 1: Arrange ultrasonic generators on both sides of the AlN coating 2 of the high temperature resistant smart bolt;

[0034] Step 2: calibrate the high temperature resistant smart bolt to obtain a relationship curve between ultrasonic echo time difference and preload force;

[0035] Step 3:

[0036] Before installing the high temperature resistant smart bolt, a pulse voltage is applied to the high temperature resistant smart bolt through an ultrasonic generator to form an ultrasonic signal, and the ultrasonic echo time T0 is measured;

[0037] After the high temperature resistant smart bolt is installed, a pulse voltage is applied to the high temperature resistant smart bolt through an ultrasonic generator to form an ultrasonic signal, and the ultrasonic echo time T1 is measured;

[0038] Step 4: Calculate the ultrasonic echo time difference T1-T0 before and after the installation of the high-temperature resistant smart bolt, and obtain the preload force of the high-temperature resistant smart bolt according to the relationship curve between the ultrasonic echo time difference and the preload force.

[0039] The high-temperature resistant smart bolt preload measurement method of the present application applies a pulse voltage on both sides of the AlN coating 2 of the high-temperature resistant smart bolt 2 through an ultrasonic generator to form an ultrasonic signal. According to the propagation characteristics of the ultrasonic wave in the bolt matrix 1, the ultrasonic echo time T can be accurately measured; finally, according to the ultrasonic echo time difference T1-T0 before and after the bolt installation and the relationship curve between the echo time difference and the preload during the calibration process of this type of high-temperature resistant smart bolt, the preload force of the high-temperature resistant smart bolt can be obtained by looking up a table.

[0040] The high-temperature resistant smart bolts and their preload measurement method of the present application overcome the failure of smart bolts in high-temperature environments, enable the preload force of aircraft engine connecting bolts to be measured and compared before and after the working state, and provide technical support for functional testing and troubleshooting of aircraft engines.

[0041] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A high temperature resistant smart bolt, characterized in that: include: A bolt base (1), wherein an AlN coating (2), a Cr coating (3), an Ag / Cr coating (4) and an Ag coating (5) are sequentially formed on the bolt head of the bolt base (1) by high-temperature sputtering.

2. The high temperature resistant smart bolt according to claim 1, characterized in that: The thickness of the AlN coating (2) is 0.5 to 1.5 micrometers.

3. The high temperature resistant smart bolt according to claim 1, characterized in that: The thickness of the Cr coating (3) is 2 to 3 micrometers.

4. The high temperature resistant smart bolt according to claim 1, characterized in that: The Ag / Cr coating (4) comprises Ag layers and Cr layers arranged alternately, and the thickness of the Ag / Cr coating (4) is 3 to 5 micrometers.

5. The high temperature resistant smart bolt according to claim 1, characterized in that: The thickness of the Ag coating (5) is 1 to 2 micrometers.

6. A method for measuring the preload force of a high temperature resistant smart bolt, based on the high temperature resistant smart bolt according to any one of claims 1 to 5, characterized in that: include: Step 1: arranging ultrasonic generators on both sides of the AlN coating (2) of the high temperature resistant smart bolt; Step 2: calibrate the high temperature resistant smart bolt to obtain a relationship curve between ultrasonic echo time difference and preload force; Step 3: Before installing the high temperature resistant smart bolt, a pulse voltage is applied to the high temperature resistant smart bolt by the ultrasonic generator to form an ultrasonic signal, and the ultrasonic echo time T0 is measured; After the high temperature resistant smart bolt is installed, a pulse voltage is applied to the high temperature resistant smart bolt through the ultrasonic generator to form an ultrasonic signal, and the ultrasonic echo time T1 is measured; Step 4: Calculate the ultrasonic echo time difference T1-T0 before and after the installation of the high temperature resistant smart bolt, and obtain the preload force of the high temperature resistant smart bolt according to the relationship curve between the ultrasonic echo time difference and the preload force.

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