Method for judging whether central axis of plate-shaped tensile sample is coaxial with force loading direction of tensile testing machine

Abstract

The invention relates to the field of tensile test application equipment, in particular to a method for judging whether a central axis of a plate-shaped tensile sample is coaxial with the force loading direction of a tensile testing machine, which comprises the following steps: opening a tensile testing machine clamp, taking down the plate-shaped tensile sample, and observing the shape of a clamping mark formed by the clamp at the clamping end of the plate-shaped tensile sample; and judging whether the tensile central axis of the plate-shaped tensile sample is coaxial with the force loading direction of the tensile testing machine or not according to the clamping mark morphology. The method has the advantages that the traditional empirical adjustment can be converted into datamation adjustment through the visual and quantifiable criterion of'clamping mark morphology-concentric circle center distance ', so that the coaxiality error between the central axis of the plate-shaped tensile sample and the force loading direction of the testing machine is controllable, recordable and traceable, and the test accuracy is improved. The additional bending moment and the additional stress caused by coaxiality deviation are effectively reduced, and the coaxiality judgment precision is remarkably improved; compared with the traditional regular calibration or external verification mode, the efficiency of the single judgment operation is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of tensile test application equipment, in particular to a method for determining whether the central axis of a plate-shaped tensile sample is coaxial with the force loading direction of a tensile testing machine. BACKGROUND

[0002] In material mechanical property testing, tensile test is an important means to evaluate the mechanical properties of metals, composite materials, etc. The coaxiality of the testing machine has a significant impact on the accuracy of the test results. According to the provisions of the national standard GB / T 228.1 "Metallic Materials Tensile Test Part 1: Room Temperature Test Method", the clamping of the sample should be as coaxial as possible to avoid additional stress caused by bending. However, in actual testing process, due to factors such as fixture wear, installation deviation or sample processing error, the central axis of the sample may not be coaxial with the force loading direction of the testing machine, resulting in deviation of the test data.

[0003] In the prior art, wedge, thread or flat pusher collet is usually used with coaxiality accessories (such as positioning sleeve ring, centering block) to ensure coaxiality. However, these accessories inevitably wear, deform or contaminate during long-term and high-frequency use, resulting in gradual decline of positioning accuracy. Once the coaxiality exceeds the allowed range, the tester often cannot find it in time and can only rely on regular calibration or experience adjustment, lacking a quick, intuitive and quantifiable on-site determination method.

[0004] For plate-shaped tensile samples, their width-thickness ratio is large and their stiffness is low, so they are more sensitive to coaxiality error. Currently, there is no determination method for the coaxiality of the central axis of a plate-shaped tensile sample and the force loading direction of a testing machine in domestic and foreign standards and public literature. The existing technology focuses on the coaxiality calibration of circular cross-section samples or relies on expensive external optical / laser centering systems, which is difficult to popularize in conventional laboratories. SUMMARY

[0005] The purpose of the present application is to provide a method for determining whether the central axis of a plate-shaped tensile sample is coaxial with the force loading direction of a tensile testing machine, to improve the coaxiality accuracy of plate-shaped tensile test and ensure that the tensile test data is more real.

[0006] To achieve the above purpose, the present application realizes the following technical scheme:

[0007] The method for determining whether the central axis of a plate-shaped tensile sample is coaxial with the force loading direction of a tensile testing machine comprises:

[0008] S1, confirming the force loading direction of the tensile testing machine;

[0009] S2, positioning the coaxiality accessories of the tensile testing machine;

[0010] S3, spray a detachable coating on the surface of the plate-shaped tensile sample;

[0011] S4, clamp the plate-shaped tensile sample against the coaxiality accessory;

[0012] S5, open the tensile tester clamp and remove the plate-shaped tensile sample, and observe the clamp mark morphology formed by the clamp end of the plate-shaped tensile sample;

[0013] S6, determine whether the tensile central axis of the plate-shaped tensile sample is coaxial with the force loading direction of the tensile tester according to the clamp mark morphology, and the content is as follows:

[0014] If not coaxial, adjust the positioning of the coaxiality accessory according to the deviation of the distance between the centers of concentric circles and the clamp end of the plate-shaped tensile sample;

[0015] Remove the detachable coating on the sample, and repeat steps S2-S6 until the central axis of the plate-shaped tensile sample is coaxial with the force loading direction of the tensile tester, so that the distance between the centers of concentric circles and the clamp end of the plate-shaped tensile sample is the same.

[0016] In S2, the positioning of the tensile tester coaxiality accessory is adjusted to the initial position.

[0017] In S3, the plate-shaped tensile sample surface is sprayed with a detachable coating, which includes a detachable coating and a detachable protective glue.

[0018] In S4, the plate-shaped tensile sample is clamped against the coaxiality accessory, and the sprayed plate-shaped tensile sample is clamped against the tensile tester clamp coaxiality accessory and clamped in the tensile tester clamp.

[0019] Compared with the prior art, the beneficial effects of the present application are:

[0020] 1. By using the visual and quantifiable criterion of "clamp mark morphology-concentric circle center distance", the traditional empirical adjustment can be converted into data adjustment, so that the coaxiality error between the central axis of the plate-shaped tensile sample and the force loading direction of the tester can be controlled, recorded and traced, the additional bending moment and additional stress caused by the coaxiality deviation are effectively reduced, and the coaxiality determination accuracy is significantly improved;

[0021] 2. Only a layer of detachable coating needs to be sprayed on the surface of the sample, and the existing tester clamp can be used to complete the determination; no high-value equipment such as laser centering instrument and optical measurement system is needed, which greatly saves laboratory cost and maintenance cost;

[0022] 3. A single judgment operation (spraying → clamping → releasing → observing → adjusting) can be completed within 3–5 minutes, which is much more efficient than the traditional periodic calibration or external verification method, and is especially suitable for rapid verification before daily or batch testing;

[0023] 4. Through daily or batch routine checks, the wear or contamination status of fixtures and coaxiality components can be detected in real time, allowing for early maintenance or replacement, avoiding "defective" testing, ensuring data reliability, and reducing downtime losses due to sudden failures.

[0024] 5. During the judgment process, the peelable coating allows a single sample to complete the judgment process (spraying → clamping → releasing → observing → adjusting → removing peelable coating → spraying → clamping → releasing → observing → adjusting). After the judgment is completed, the peelable coating is completely removed, and the formal test uses uncoated samples, which eliminates the possible interference of the coating on the friction coefficient, stress concentration and fracture location, ensuring that the test results are pure and reliable. Attached Figure Description

[0025] Figure 1 This is a flowchart for determining whether the central axis of a plate-shaped tensile specimen is coaxial with the direction of force loading of the tensile testing machine.

[0026] Figure 2 The specimen's central axis is not parallel to the testing machine's tensile axis and they intersect.

[0027] Figure 3 The center axis of the specimen is parallel to, but not on, the tensile axis of the testing machine.

[0028] Figure 4 The center axis of the specimen is parallel and coaxial with the tensile axis of the testing machine. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0030] The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0031] Example 1

[0032] See Figure 1 Methods for determining whether the central axis of a plate-shaped tensile specimen is coaxial with the direction of force loading in a tensile testing machine include:

[0033] S1. Confirm the direction of force loading on the tensile testing machine.

[0034] S2. Adjust the positioning of the coaxiality fitting of the tensile testing machine fixture to the initial position.

[0035] S3, spray a layer of peelable coating on the surface of the plate-shaped tensile specimen, the peelable coating comprising a peelable coating material and a peelable protective glue.

[0036] S4, tightly attach the sprayed plate-shaped tensile specimen to the coaxiality accessory of the tensile tester clamp, and clamp it in the tensile tester clamp.

[0037] S5, open the tensile tester clamp and remove the plate-shaped tensile specimen, and observe the clamp mark morphology formed by the clamp end of the plate-shaped tensile specimen.

[0038] S6, judge whether the tensile central axis of the plate-shaped tensile specimen is coaxial with the force loading direction of the tensile tester according to the clamp mark morphology, as follows:

[0039] If not coaxial, adjust the positioning of the coaxiality accessory according to the deviation of the concentric circle center from the distance (circle) between the two sides of the clamp end of the plate-shaped tensile specimen;

[0040] Remove the peelable coating on the specimen, and repeat steps S2-S6 until the central axis of the plate-shaped tensile specimen is coaxial with the force loading direction of the tensile tester, so that the concentric circle center in the clamp mark morphology is the same distance (i.e. the same number of circles) from the clamp end of the plate-shaped tensile specimen.

[0041] S7, perform subsequent conventional tensile test detection.

[0042] Example 2

[0043] In this embodiment, the method for determining whether the central axis of the plate-shaped tensile specimen is coaxial with the force loading direction of the tensile tester is the same as in Example 1, and the case where the tensile central axis of the plate-shaped tensile specimen is not coaxial with the force loading direction of the tester is added based on it.

[0044] There are three states of the specimen central axis and the tester tensile axis, namely Figure 2 The specimen central axis and the tester tensile axis are not parallel and intersect, the blue solid line is the tester tensile axis, and the black dashed line is the specimen central axis. By observation, it is found that the upper and lower tensile tester clamp coaxiality accessories need to be adjusted in opposite directions.

[0045] Figure 3 The specimen central axis and the tester tensile axis are parallel but not coaxial, and by observation, it is found that the upper and lower tensile tester clamp coaxiality accessories need to be adjusted in the same direction.

[0046] Figure 4 The specimen central axis and the tester tensile axis are parallel and coaxial, which is what we ultimately want to achieve, proving that the specimen central axis and the tester tensile axis are coaxial, and the test can be performed.

[0047] The application can convert the traditional experience adjustment into data adjustment through the visual and quantifiable criterion of "clip mark morphology - concentric circle center distance", so that the coaxiality error of the center axis of the plate-shaped tensile sample and the loading direction of the testing machine can be controlled, recorded and traced, the additional bending moment and additional stress caused by the coaxiality deviation are effectively reduced, the coaxiality determination accuracy is significantly improved, only a layer of peelable coating needs to be sprayed on the surface of the sample, and the existing testing machine clamp can be used to complete the determination, high-value equipment such as a laser centering instrument and an optical measurement system are not needed, the laboratory cost and maintenance cost are greatly saved, a single determination operation (spraying, clamping, loosening, observing, adjusting) can be completed within 3-5 minutes, the efficiency is improved by 5-10 times compared with the traditional periodic calibration or external calibration mode, and the application is particularly suitable for rapid calibration before daily or batch testing, through daily or batch routine determination, the wear or pollution state of the clamp and the coaxiality accessory can be found in real time, and the clamp and the coaxiality accessory can be maintained or replaced in advance, so that the "sick" test is avoided, the data reliability is ensured, and the downtime loss caused by sudden failure is reduced, during the determination process, the peelable coating can realize the determination process (spraying, clamping, loosening, observing, adjusting, removing the peelable coating, spraying, clamping, loosening, observing, adjusting) of a single sample, after the determination is completed, the peelable coating is completely removed, the formal test adopts the un-sprayed sample, the possible interference of the coating on the friction coefficient, stress concentration and fracture position is eliminated, and the test result is ensured to be pure and reliable.

Claims

1. A method of determining that the central axis of a plate-like tensile test specimen is coaxial with the force loading direction of a tensile testing machine, characterized in that The application relates to a method for adjusting the coaxiality of a tensile testing machine, and belongs to the field of tensile testing machine coaxiality adjustment. S1, confirming the force loading direction of the tensile testing machine; S2, positioning the tensile testing machine coaxiality accessory; S3, spraying a detachable coating on the surface of the plate-shaped tensile sample; S4, clamping the plate-shaped tensile sample closely to the coaxiality accessory; S5, opening the tensile testing machine clamp and taking off the plate-shaped tensile sample, and observing the clamp mark morphology formed by the clamp end of the plate-shaped tensile sample; S6, judging whether the tensile center axis of the plate-shaped tensile sample is coaxial with the force loading direction of the tensile testing machine according to the clamp mark morphology, and the content is as follows: If the axes are not coaxial, the positioning of the coaxiality accessory is adjusted according to the deviation of the distance between the concentric circle center and the clamp end of the plate-shaped tensile sample; The detachable coating on the sample is removed, and steps S2-S6 are repeated until the center axis of the plate-shaped tensile sample is coaxial with the force loading direction of the tensile testing machine, so that the distance between the concentric circle center and the clamp end of the plate-shaped tensile sample is the same.

2. The method of determining that the center axis of a plate-like tensile specimen is coaxial with the force application direction of a tensile testing machine according to claim 1, characterized by, In S2, the positioning of the tensile testing machine coaxiality accessory is adjusted to the initial position.

3. The method of determining that the center axis of a plate-shaped tensile test specimen is coaxial with the force application direction of a tensile testing machine according to claim 1, characterized by, In S3, the detachable coating is sprayed on the surface of the plate-shaped tensile sample, and the detachable coating comprises detachable paint and detachable protective glue.

4. The method of determining that the center axis of a plate-shaped tensile specimen is coaxial with the force application direction of a tensile testing machine according to claim 1, characterized by, In S4, the plate-shaped tensile sample is clamped closely to the tensile testing machine clamp coaxiality accessory.

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