Device and method for testing mechanical property of high-temperature-resistant inclined coil spring

Abstract

The invention discloses a device and method for testing the mechanical property of a high-temperature-resistant inclined coil spring, and relates to the technical field of hypersonic aircrafts, the device comprises a fixed support, a movable support and balls, and the inclined coil spring is arranged on the upper surface of the movable support; when an upper pressure head of the universal testing machine applies pressure to the inclined coil spring, static friction force between the inclined coil spring and the movable support is converted into static friction force and rolling friction force between the ball and the fixed support and between the ball and the movable support, and slippage of the inclined coil spring and the movable support is eliminated. The testing device is arranged in the heating furnace, the inclined coil spring can be heated through the heating furnace and maintained at the target temperature, and the mechanical property of the inclined coil spring can be effectively and accurately measured under the high-temperature condition.

Description

Technical Field

[0001] The present invention relates to the technical field of hypersonic aircraft, and particularly to a testing device and a testing method for the mechanical properties of a high-temperature-resistant conical coil spring. Background Art

[0002] At present, the stringent high-temperature dynamic sealing technology required by hypersonic propulsion systems is one of the technical difficulties restricting the development of hypersonic aircraft. During the reentry process of a hypersonic aircraft, when high-pressure hot gas enters the gap of the control wing with low pressure, in-gap flow and aerodynamic heating will occur. In severe cases, it will cause damage or even failure of the low-temperature components at the bottom of the control wing gap of the aircraft, and further lead to the loss of control of the aircraft. Therefore, in order to ensure the normal operation of the low-temperature components, heat insulation and sealing treatment must be carried out, and the seal needs to have sufficient elastic deformation ability to adapt to the high-frequency micro-movement of the gap during flight and the gap change caused by thermal expansion. The high-temperature-resistant metal conical coil spring has many advantages such as providing an approximately constant resilience within a certain deformation range (35%), and is considered to be an ideal component for high-temperature sealing.

[0003] In the prior art, there is a lack of a testing device and a testing method for the mechanical properties of a conical coil spring in a high-temperature environment. At the same time, due to the special structure of the conical coil spring, when subjected to radial stress, a component stress will be generated in the axial direction. When the axial component stress is greater than the static friction force between the conical coil spring and the test fixture, slippage will occur between the conical coil spring and the test fixture, and its radial stress will drop significantly, resulting in a large error in the test results, which is not conducive to determining the constant load and the deformation range of the load platform of the conical coil spring.

[0004] Whether the mechanical properties of the conical coil spring under high-temperature conditions can be effectively and accurately measured has an important impact on the design and manufacture of hypersonic propulsion systems. In view of this, how to provide a testing device and a testing method that can avoid slippage between the conical coil spring and the fixture in a high-temperature environment is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a testing device and a testing method for the mechanical properties of a high-temperature-resistant conical coil spring to solve the problems existing in the prior art.

[0006] To achieve the above purpose, the present invention provides a testing device for the mechanical properties of a high-temperature-resistant conical coil spring, including:

[0007] A fixed bracket, the lower surface of which is arranged on the lower pressing head of a universal testing machine, and at least three first installation grooves are defined on the upper surface thereof;

[0008] The movable bracket is arranged on the fixed bracket. The lower surface of the movable bracket defines a second installation groove, which corresponds to the plurality of first installation grooves. The first installation groove and the second installation groove form an installation chamber;

[0009] The ball is arranged in the installation chamber and is respectively in contact with the bottom of the first installation groove and the bottom of the second installation groove;

[0010] The conical coil spring is arranged on the upper surface of the movable bracket; when the upper pressure head of the universal testing machine presses on the conical coil spring, the static friction force between the conical coil spring and the upper surface of the movable bracket is greater than the static friction force and rolling friction force between the ball and the fixed bracket and the movable bracket.

[0011] Further, the fixed bracket, the movable bracket and the ball are made of ceramic materials.

[0012] Further, there are four first installation grooves, and the balls are respectively arranged in the four first installation grooves.

[0013] Further, there are four balls, which are arranged in the four first installation grooves in one-to-one correspondence.

[0014] Further, the outer diameter of the ball is greater than the height of the installation chamber.

[0015] Further, it further includes:

[0016] A heating furnace, in which the fixed bracket, the movable bracket, the ball, the upper pressure head and the lower pressure head of the universal testing machine are arranged.

[0017] The present invention also provides a testing method for the mechanical properties of a high-temperature-resistant conical coil spring, which is characterized in that the testing device for the mechanical properties of the high-temperature-resistant conical coil spring according to any one of claims 1-6 is applied, and it includes the following steps:

[0018] S1: Place the conical coil spring on the upper surface of the movable bracket, and perform 2-3 turns of cyclic loading on the conical coil spring through a universal testing machine at room temperature to compress and fix the conical coil spring;

[0019] S2: Measure the parameters of the compressed and fixed conical coil spring;

[0020] S3: Reset the universal testing machine, arrange the fixed bracket, the movable bracket, the ball, the upper pressure head and the lower pressure head of the universal testing machine in the heating furnace, close the furnace door of the heating furnace, heat the conical coil spring to a preset temperature and maintain the temperature;

[0021] S4: Apply cyclic loading to the conical coil spring through a universal testing machine. The static friction force between the conical coil spring and the movable bracket is converted into the static friction force and rolling friction force between the ball and the fixed bracket and the movable bracket, and the load-displacement curve of the conical coil spring at the target temperature is obtained.

[0022] S5: Cool the conical coil spring to room temperature, reset the universal testing machine, and measure the parameters of the conical coil spring again.

[0023] S6: Calculate the resilience rate of the conical coil spring. The calculation formula is as follows:

[0024]

[0025] Wherein, R is the resilience rate of the conical coil spring, l is the compression amount of the conical coil spring; h1 and h2 are the heights of the conical coil spring measured in step S2 and step S5 respectively.

[0026] Further, in step S1, the compression amount of the pressed conical coil spring is 10% of the height of the conical coil spring - the coiling compression amount.

[0027] Further, in step S3, the highest target temperature is 1600 °C.

[0028] Further, in step S4, the inlet force of the cyclic loading of the universal testing machine on the conical coil spring is 0.1 - 0.6 N.

[0029] The present invention discloses the following technical effects:

[0030] 1. Arrange a movable bracket, a ball and a fixed bracket between the conical coil spring and the lower pressing head of the universal testing machine. Convert the static friction force between the conical coil spring and the movable bracket into the static friction force and rolling friction force between the ball and the fixed bracket and the movable bracket, eliminate the slip between the conical coil spring and the movable bracket, enable the test result to directly reflect the intrinsic performance of the conical coil spring, and improve the accuracy and reliability of the test result.

[0031] 2. The test device is arranged in a heating furnace, and the conical coil spring can be heated and maintained at the target temperature through the heating furnace, realizing effective and accurate measurement of the mechanical properties of the conical coil spring under high temperature conditions.

[0032] 3. The fixed bracket defines a plurality of first installation grooves, and the balls are arranged corresponding to the first installation grooves to limit the displacement range of the balls, avoiding excessive relative displacement between the fixed bracket and the movable bracket, and further improving the stability of the conical coil spring. Description of the Drawings

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the attached drawings required in the embodiments. Obviously, the attached drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other attached drawings can be obtained based on these attached drawings.

[0034] Figure 1 Structural schematic diagram of the present invention;

[0035] Figure 2 Load-displacement curve of the inclined coil spring corresponding to Embodiment 1;

[0036] Figure 3 Load-displacement curve of the inclined coil spring corresponding to Embodiment 2;

[0037] Wherein, 1. Movable bracket; 2. Ball; 3. Fixed bracket. Specific implementation manner

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the attached drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0039] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the attached drawings and specific implementation manners.

[0040] The embodiment of the present invention provides a test device for the mechanical properties of a high-temperature resistant inclined coil spring, including:

[0041] A fixed bracket 3, the lower surface of which is arranged on the lower pressure head of a universal testing machine, and at least three first installation grooves are defined on the upper surface thereof;

[0042] A movable bracket 1 is arranged on the fixed bracket 3. The lower surface of the movable bracket 1 defines a second installation groove, and the second installation groove corresponds to a plurality of first installation grooves. The first installation groove and the second installation groove form an installation chamber;

[0043] Balls 2 are arranged in the installation chamber and are respectively in contact with the bottom of the first installation groove and the bottom of the second installation groove;

[0044] An inclined coil spring is arranged on the upper surface of the movable bracket 1; when the upper pressure head of the universal testing machine presses on the inclined coil spring, the static friction force between the inclined coil spring and the upper surface of the movable bracket 1 is much greater than the static friction force and rolling friction force between the balls 2 and the fixed bracket 3 and the movable bracket 1.

[0045] In this embodiment, the fixed support 3, the movable support 1, and the rolling balls 2 are made of ceramic materials, such as high-temperature resistant and high-hardness ceramic materials like SiC and Si3N4.

[0046] In this embodiment, both the fixed support 3 and the movable support 1 are cylinders. The second installation groove is a circular groove concentric with the movable support 1. A circular groove adapted to the second installation groove is defined on the fixed support 3. Two partition plates are arranged in the vertical and horizontal directions to divide the circular groove into four first installation grooves. There are four rolling balls 2, which are respectively arranged in the four first installation grooves in one-to-one correspondence.

[0047] In this embodiment, the outer diameter of the rolling balls 2 is slightly larger than the height of the installation chamber.

[0048] In this embodiment, it further includes:

[0049] A heating furnace, in which the fixed support 3, the movable support 1, the rolling balls 2, the upper pressure head and the lower pressure head of the universal testing machine are arranged.

[0050] The present invention also provides a method for testing the mechanical properties of a high-temperature resistant inclined coil spring, which is characterized in that a testing device for the mechanical properties of a high-temperature resistant inclined coil spring according to any one of claims 1-6 is applied, and it includes the following steps:

[0051] S1: Before the test, measure the parameters of the inclined coil spring. The parameters include dimensions such as height, width, length, wire diameter, pitch, etc.; place the inclined coil spring on the upper surface of the movable support 1, and perform 2-3 turns of cyclic loading on the inclined coil spring through a universal testing machine at room temperature to compress and fix the inclined coil spring;

[0052] S2: Measure the parameters of the compressed and fixed inclined coil spring;

[0053] S3: Reset the universal testing machine, arrange the fixed support 3, the movable support 1, the rolling balls 2, the upper pressure head and the lower pressure head of the universal testing machine in the heating furnace, close the furnace door of the heating furnace, heat the inclined coil spring to a preset temperature and maintain the temperature;

[0054] S4: Cyclically load the inclined coil spring through the universal testing machine. The static friction force between the inclined coil spring and the movable support 1 is converted into the static friction force and rolling friction force between the rolling balls 2 and the fixed support 3 and the movable support 1, and a load-displacement curve of the inclined coil spring at the target temperature is obtained;

[0055] S5: Cool the inclined coil spring to room temperature, reset the universal testing machine, and measure the parameters of the inclined coil spring again;

[0056] S6: Calculate the springback rate of the inclined coil spring. The calculation formula is as follows:

[0057]

[0058] Wherein, R is the resilience rate of the inclined coil spring, ι is the compression amount of the inclined coil spring; h1 and h2 are respectively the heights of the inclined coil spring measured in step S2 and step S5;

[0059] S7: Store the inclined coil spring and the test device to complete the test.

[0060] In this embodiment, in step S1, the compression amount of the pressed inclined coil spring is 10% of the height of the inclined coil spring - the coiling compression amount.

[0061] In this embodiment, in step S3, the target temperature is at most 1600 °C.

[0062] In this embodiment, in step S4, the inlet force applied by the universal testing machine to the inclined coil spring in cyclic loading is 0.1 - 0.6 N.

[0063] Example 1

[0064] The above embodiment is used to test the high-temperature mechanical properties of the inclined coil spring made of GH4282 superalloy.

[0065] In step S1, the compression amount of the pressed inclined coil spring is 35% of the height of the inclined coil spring;

[0066] In step S3, the target temperature is 950 °C, and the temperature holding time is 10 min;

[0067] In step S4, the inlet force applied by the universal testing machine to the inclined coil spring in cyclic loading is 0.2 N, the compression amount in cyclic loading is 35% of the height of the inclined coil spring after pressing, and the number of cycles is 1 time.

[0068] The load-displacement curve of the inclined coil spring is as Figure 2 shown.

[0069] Example 2

[0070] The above embodiment is used to test the high-temperature mechanical properties of the inclined coil spring made of molybdenum-rhenium refractory alloy.

[0071] In step S1, the compression amount of the pressed inclined coil spring is 35% of the height of the inclined coil spring;

[0072] In step S3, the target temperature is 1300 °C, and the temperature holding time is 10 min;

[0073] In step S4, the inlet force applied by the universal testing machine to the inclined coil spring in cyclic loading is 0.6 N, the compression amount in cyclic loading is 2 mm, and the number of cycles is 1 time.

[0074] The load-displacement curve of the inclined coil spring is as Figure 3 shown.

[0075] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0076] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A testing device for the mechanical properties of a high-temperature-resistant inclined coil spring, characterized in that, Comprising: A fixed bracket (3), the lower surface of which is arranged on the lower pressing head of a universal testing machine, and at least three first mounting grooves are defined on its upper surface; A movable bracket (1), arranged on the fixed bracket (3), the lower surface of the movable bracket (1) defines a second mounting groove, the second mounting groove corresponds to a plurality of the first mounting grooves, and the first mounting groove and the second mounting groove form a mounting chamber; Ball bearings (2), arranged in the mounting chamber and respectively in contact with the bottom of the first mounting groove and the bottom of the second mounting groove; An inclined coil spring, arranged on the upper surface of the movable bracket (1); when the upper pressing head of the universal testing machine presses on the inclined coil spring, the static friction force between the inclined coil spring and the upper surface of the movable bracket (1) is greater than the static friction force and rolling friction force between the ball bearings (2) and the fixed bracket (3) and the movable bracket (1).

2. The testing device for the mechanical properties of a high-temperature-resistant inclined coil spring according to claim 1, wherein, The fixed bracket (3), the movable bracket (1) and the ball bearings (2) are made of ceramic materials.

3. The testing device for the mechanical properties of a high-temperature-resistant inclined coil spring according to claim 1, wherein There are four of the first mounting grooves, and the ball bearings (2) are respectively arranged in the four first mounting grooves.

4. The testing device for the mechanical properties of a high-temperature-resistant inclined coil spring according to claim 3, characterized in that, There are four of the ball bearings (2), and they are arranged in the four first mounting grooves in one-to-one correspondence.

5. The testing device for the mechanical properties of a high-temperature-resistant inclined coil spring according to claim 1, wherein The outer diameter of the ball bearings (2) is greater than the height of the mounting chamber.

6. The testing device for the mechanical properties of a high-temperature-resistant inclined coil spring according to claim 1, wherein, Further comprising: A heating furnace, the fixed bracket (3), the movable bracket (1), the ball bearings (2) and the upper pressing head and the lower pressing head of the universal testing machine are arranged in the heating furnace.

7. A test method for the mechanical properties of a high-temperature-resistant inclined coil spring, characterized in that, Applying the testing device for the mechanical properties of the high-temperature resistant inclined coil spring according to any one of claims 1-6, comprising the following steps: S1: Place the inclined coil spring on the upper surface of the movable bracket (1), and perform 2-3 turns of cyclic loading on the inclined coil spring through the universal testing machine at room temperature to compress and fix the inclined coil spring; S2: Measure the parameters of the compressed and fixed inclined coil spring; S3: Reset the universal testing machine, arrange the fixed bracket (3), the movable bracket (1), the ball bearings (2) and the upper pressing head and the lower pressing head of the universal testing machine in the heating furnace, close the furnace door of the heating furnace, heat the inclined coil spring to a preset temperature and maintain the temperature; S4: Perform cyclic loading on the inclined coil spring through the universal testing machine, and the static friction force between the inclined coil spring and the movable bracket (1) is converted into the static friction force and rolling friction force between the ball bearings (2) and the fixed bracket (3) and the movable bracket (1), so as to obtain the load-displacement curve of the inclined coil spring at the target temperature; S5: Cool the inclined coil spring to room temperature, reset the universal testing machine, and measure the parameters of the inclined coil spring again; S6: Calculate the springback rate of the inclined coil spring, and the calculation formula is as follows: Wherein, R is the springback rate of the inclined coil spring, l is the compression amount of the inclined coil spring; h1 and h2 are respectively the heights of the inclined coil spring measured in step S2 and step S5.

8. A test method for the mechanical properties of a high-temperature-resistant inclined coil spring according to claim 7, characterized in that In step S1, the compression amount for compressing and fixing the inclined coil spring is 10% of the height of the inclined coil spring - the coiling compression amount.

9. The testing method for the mechanical properties of a high-temperature-resistant inclined coil spring according to claim 7, characterized in that, In step S3, the highest target temperature is 1600°C.

10. The testing method for the mechanical properties of a high-temperature-resistant inclined coil spring according to claim 7, characterized in that, In step S4, the inlet force for the universal testing machine to perform cyclic loading on the inclined coil spring is 0.1-0.6N.

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