Clamp for high-temperature endurance test
By adopting a rotatable convex spherical and concave spherical clamp design in high-temperature endurance tests, the problem of specimen bending moment caused by coaxiality error is solved, and the accuracy and safety of test data are improved.
Patent Information
- Application Number
- CN202521768073.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-20
- Publication Date
- 2025-10-17
- Estimated Expiration
- 2035-08-20
AI Technical Summary
In existing high-temperature endurance tests, rigid connections cause the specimen to bear additional bending moments due to coaxiality errors, affecting the accuracy and safety of test data.
The design of relatively rotatable convex spherical clamping blocks and concave spherical clamping blocks is adopted. The coaxiality error is offset by automatic adjustment through spherical fit, ensuring that the load is mainly transmitted along the axial direction.
It effectively reduces the bending moment on the specimen, improves the accuracy and reliability of high temperature endurance tests, and ensures the stability and security of test data.
Smart Images
Figure CN223449654U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to a kind of clamps for high temperature endurance test, belong to test fixture technical field. BACKGROUND
[0002] The high temperature endurance performance of metal material is the key index to measure its ability to withstand constant load for a long time in high temperature environment, which is directly related to the safety and reliability of key components in high-end equipment such as aerospace, energy power and petrochemical industry. In the design and manufacture of core components such as turbine blades of aircraft engines and superheater tubes of power stations, the high temperature endurance performance data of materials is an important basis for evaluating the service life of components and ensuring operation safety, so there is a high requirement for the accuracy and reliability of high temperature endurance test.
[0003] The core requirement of high temperature endurance test is to ensure that the test sample only bears axial constant load, and to avoid distortion of test data caused by additional bending moment, shear force and other directional stress. However, in the prior art, the connection between high temperature endurance test sample and clamp is mostly rigid connection such as threaded connection. Although this connection method can realize load transmission, the loading system composed of testing machine, pull rod and clamp is easily affected by various factors during the test: on the one hand, the mechanical wear of equipment parts after long-term use will cause deviation of initial coaxiality; on the other hand, the thermal expansion and stress deformation of materials in high temperature environment will further aggravate the coaxiality error of upper and lower pull rods.
[0004] Rigid connection cannot compensate for the above-mentioned coaxiality error, so that the test sample is inevitably subjected to additional bending moment while bearing axial load. This not only causes the test data to deviate from the real performance of the material, resulting in large error, but also may cause unexpected fracture of the test sample in severe cases, directly affecting the effectiveness of the test, and even misleading material selection and component design. SUMMARY
[0005] The utility model aims at: in view of the above problems, provide a kind of clamp for high temperature endurance test, can automatically adjust offset coaxiality error, reduce test sample additional bending moment.
[0006] The technical scheme adopted by the utility model is as follows:
[0007] A kind of clamp for high temperature endurance test, including clamp main body, convex spherical clamping block and concave spherical clamping block;The top of the clamp main body is provided with a connecting structure for connecting with the pull rod of testing machine, and the lower part of the clamp main body is provided with a cavity structure;The convex spherical clamping block and the concave spherical clamping block for clamping test sample are arranged in the cavity structure, and the convex spherical clamping block and the concave spherical clamping block are relatively rotatable.
[0008] The connecting structure at the top of the clamp body is used to stably connect with the pull rod of the testing machine, so as to realize effective transmission of the load from the testing machine to the clamp. The cavity structure at the lower part provides installation space for the convex spherical clamping block and the concave spherical clamping block, so as to ensure the position stability of the two when clamping the sample. The convex spherical clamping block and the concave spherical clamping block cooperate to clamp the sample, and the relative rotation of the two is the core. The rotation capability allows them to adjust the relative position according to the stress condition during the test. The combination of the three enables the clamp to have an automatic adjustment capability. When there is a coaxiality error in the pull rod of the testing machine, the relative rotation of the convex spherical clamping block and the concave spherical clamping block can offset the error through position adjustment, so as to ensure that the load is closer to the axial transmission to the sample. The rigid connection will cause the sample to bear additional bending moment due to the error, while the clamp automatically adjusts through the relatively rotatable clamping block, reduces the non-axial stress borne by the sample, reduces the error of the test data, improves the accuracy and reliability of the high-temperature durability test results, and solves the problem that the rigid connection cannot compensate for the coaxiality error.
[0009] Alternatively, the connecting structure of the clamp body is a threaded segment used to form a threaded connection with the pull rod of the durability testing machine. It can ensure the stable combination between the clamp and the pull rod, and it is not easy to loosen under the long-term constant load of the high-temperature durability test, so as to ensure the continuous and stable transmission of the load from the pull rod of the testing machine to the clamp body, and provide a reliable foundation for the subsequent transmission of force to the sample. When there is a coaxiality error in the pull rod of the testing machine, the threaded connection ensures the basic stability of the load transmission path, and the relative rotation of the convex spherical clamping block and the concave spherical clamping block can be flexibly adjusted on this basis to offset the error through automatic adaptation.
[0010] Alternatively, the outer edge of the bottom of each convex spherical clamping block is a convex sphere, and the inner side of the top of the convex spherical clamping block is provided with a conformal groove matched with the end of the sample. The inner side of the top of each concave spherical clamping block is a concave sphere, and the concave sphere is matched with the bottom of the convex spherical clamping block. The convex sphere at the outer edge of the bottom of each convex spherical clamping block and the concave sphere at the inner side of the top of the concave spherical clamping block are matched with each other to provide a relatively rotatable contact basis for the two. The spherical surface cooperation allows the convex spherical clamping block to flexibly adjust the angle on the concave spherical clamping block to adapt to the stress changes in different directions. The conformal groove at the inner side of the top of the convex spherical clamping block is matched with the end of the sample, which can closely fit the contour of the end of the sample, so as to ensure the stable clamping of the sample and avoid the sliding or deviation of the sample during the test, and ensure the stable transmission of the load from the clamping block to the sample.
[0011] Alternatively, the cavity structure of the clamp body is a cylindrical cavity, the cylindrical cavity is provided with a square opening penetrating through the side surface, the convex spherical clamping block and the concave spherical clamping block can pass through the square opening and be installed in the cylindrical cavity, the bottom of the cylindrical cavity is provided with a radial slot penetrating through, and the radial slot is in communication with the square opening and the cylindrical cavity; the concave spherical clamping block and the convex spherical clamping block are both provided with a cylindrical opening for passing through the sample. The cylindrical cavity of the clamp body provides a suitable installation space for the convex spherical clamping block and the concave spherical clamping block, the square opening penetrating through the side surface facilitates the convex spherical clamping block and the concave spherical clamping block to pass into the cavity from the side to complete the assembly, simplifies the installation process, and ensures that the clamping block can accurately enter the working position. The radial slot at the bottom of the cylindrical cavity is in communication with the square opening and the cavity, providing a passage for the sample to pass in, so that the end of the sample can smoothly enter the cavity and cooperate with the clamping block, and the slot space allows the sample to swing moderately when subjected to stress. The cylindrical openings on the concave spherical clamping block and the convex spherical clamping block are for the sample to pass through, which not only realizes effective clamping of the end of the sample, but also avoids interference with the working section of the sample.
[0012] Alternatively, the middle part of the slot is provided with a through hole with a diameter greater than the slot width; and the diameter of the cylindrical opening of the concave spherical clamping block is greater than the diameter of the working section of the sample and less than the diameter of the end of the sample. The through hole with a diameter greater than the slot width in the middle part of the slot provides more space for the movement of the sample in the slot, which can further increase the freedom of the sample to swing in all directions. When there is a coaxiality error in the pull rod of the testing machine, the sample can adjust its posture more flexibly with the help of this space, reducing the additional stress caused by limited position. The diameter of the cylindrical opening of the concave spherical clamping block is greater than the diameter of the working section of the sample, so that the working section of the sample can smoothly pass through the opening, avoiding the opening from pressing or binding the working section, and ensuring that the working section only bears axial load; and the diameter of the opening is less than the diameter of the end of the sample, which can reliably hold the end of the sample, preventing the sample from falling off the clamping block during the test process, and ensuring the stability of clamping.
[0013] Alternatively, the bottom of the cylindrical cavity is provided with a clamping groove for abutting with the bottom of the concave spherical clamping block, and the convex spherical clamping block is above the concave spherical clamping block. The axial position of the concave spherical clamping block can be limited, preventing it from moving axially along the cavity under the action of test load, ensuring the stability of the installation position of the concave spherical clamping block in the cavity, and providing a stable foundation for the cooperation of the convex spherical clamping block and the concave spherical clamping block. The convex spherical clamping block is above the concave spherical clamping block, so that the spherical structures of the two can be precisely fitted, ensuring that the contact is sufficient and the stress is uniform when rotating relatively, without affecting the adjustment rotation caused by the coaxiality error of the two, and being able to stably transmit the test load.
[0014] Alternatively, the convex spherical clamping blocks are symmetrically arranged in at least two pieces, and / or the concave spherical clamping blocks are symmetrically arranged in at least two pieces. The splicing structure facilitates installation in the cavity, and each piece can be combined after entering the cavity to clamp the sample in the convex spherical clamping block and the concave spherical clamping block, thereby adapting to the space limitation of the cavity. The concave spherical clamping block is also spliced from at least two parts of the same shape, which can ensure the adaptability of the outer cylindrical surface to the cylindrical cavity of the clamp body, and the inner concave spherical surface can also be symmetrical and precisely fit the convex spherical surface of the convex spherical clamping block, thereby ensuring the smoothness when the two relatively rotate. The splicing parts of the same shape reduce the processing difficulty and cost, and have strong interchangeability, thereby facilitating maintenance and replacement.
[0015] Alternatively, the splicing seams of the convex spherical clamping blocks and the concave spherical clamping blocks are staggered. The splicing seam is often a position with relatively low structural strength, and the staggered arrangement can disperse stress, avoid the splicing seams of the two from coinciding to form a weak area on the same plane, make the clamping block bear force more evenly when transmitting load, prevent local stress concentration from causing damage to the clamping block, and ensure the stability of clamping. Meanwhile, this arrangement can make the contact between the convex spherical clamping block and the concave spherical clamping block more continuous, and when the two relatively rotate and adjust, there will be no gap or jamming due to the alignment of the splicing seams, thereby ensuring the smoothness and flexibility of the adjustment process.
[0016] Alternatively, the clamp body is made of a high-temperature-resistant alloy material. The clamp body needs to provide stable support for the entire clamp structure, the top thereof needs to be stably connected with a testing machine pull rod, and the bottom cavity structure needs to bear the load transmitted by the convex spherical clamping block, the concave spherical clamping block and the sample. The high-temperature-resistant alloy material can maintain stable mechanical properties in a high-temperature environment of a high-temperature durability test, thereby avoiding structural deformation or strength reduction caused by high temperature. This ensures that the connection structure of the top of the clamp body and the testing machine pull rod is always stable, and the cavity structure at the bottom can also maintain a predetermined shape to provide a stable mounting space and support for the convex spherical clamping block and the concave spherical clamping block.
[0017] Alternatively, the convex spherical clamping block and the concave spherical clamping block are made of a high-temperature-resistant ceramic material. The two need to relatively rotate through spherical surface cooperation to adjust the coaxiality error. The high-temperature-resistant ceramic material can maintain stable structure and performance in a high-temperature environment of a high-temperature durability test, thereby avoiding deformation or performance degradation caused by high temperature, ensuring that the spherical surface cooperation of the two is always accurate and the relative rotation is smooth. The ceramic material has a smooth surface, which can reduce the frictional resistance between the convex spherical surface and the concave spherical surface, so that the clamping block can relatively rotate more flexibly when it needs to be adjusted, and better respond to the coaxiality error and automatically adjust.
[0018] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present application are as follows:
[0019] 1. The utility model provides a kind of fixture for high temperature endurance test, the structural design of fixture main body provides stable installation space for clamping block, the reliable connection of its top connecting structure is ensured with test machine pull rod, the cavity of bottom and relevant opening and slot then facilitate the assembly of clamping block and sample, and provide freedom degree for sample swing.The spherical surface cooperation design of convex spherical surface clamping block and concave spherical surface clamping block makes that both can relatively rotate, can automatically adjust under the action of test load to offset the coaxiality error of upper and lower pull rod, effectively reduce the possibility of sample to bear bending moment.
[0020] 2, The utility model provides a kind of fixture for high temperature endurance test, fixture main body uses high-temperature-resistant alloy material, clamping block uses high-temperature-resistant ceramic material, guarantee the structural stability and functional reliability of each component under high temperature environment, ensure that the adjustment function of clamping block continues effectively.The combination of these technical solutions greatly improves the accuracy and reliability of high temperature endurance test test data, solves the problem of test data deviation caused by coaxiality error of traditional rigid connection. BRIEF DESCRIPTION OF DRAWINGS
[0021] Figure 1 It is the structure schematic view of a kind of fixture for high temperature endurance test in the embodiment of the application;
[0022] Figure 2 It is the structure schematic view of fixture main body in the embodiment of the application;
[0023] Figure 3 It is the structure schematic view of convex spherical surface clamping block in the embodiment of the application;
[0024] Figure 4 It is the structure schematic view of concave spherical surface clamping block in the embodiment of the application;
[0025] Figure 5 It is the assembly schematic view of concave and convex spherical surface clamping block in the embodiment of the application;
[0026] Figure 6 It is the section structure schematic view after the embodiment of the application clamps sample.
[0027] Mark in drawing:1-fixture main body, 11-connecting thread, 12-cavity structure, 13-square opening, 14-slotted, 15-through hole, 2-convex spherical surface clamping block, 21-sample conformal groove, 3-concave spherical surface clamping block, 31-cylindrical opening, 4-sample. DETAILED DESCRIPTION
[0028] The utility model is described in detail in combination with the drawings.
[0029] In order to make the utility model purposes, technical scheme and advantages more clearly, the following will be further described in detail with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the utility model, and are not used to limit the utility model. It should be noted that, except for the dependent embodiments, any embodiment is independently existing, and the implementation or non-implementation does not affect the scheme integrity of the remaining embodiments, and the implementation or non-implementation of the dependent embodiment also does not affect the scheme integrity of the original embodiment.
[0030] Referring to Figures 1-6 The embodiment provides a kind of fixture for high temperature endurance test, including fixture main body 1, convex spherical clamping block 2 and concave spherical clamping block 3.Fixture main body 1 is round stick, one end is equipped with connecting thread 11, the other end has cylindrical cavity, convex spherical clamping block 2 and concave spherical clamping block 3, and the sample 4 to be examined respectively enter cylindrical cavity inside through cylindrical cavity side opening after being assembled and installed in cavity inside.
[0031] In the embodiment, fixture main body 1 is cylindrical, one end is equipped with thread, and forms threaded connection with the pull rod on high temperature endurance testing machine, top is equipped with cavity structure 12, cavity inner wall has clamping groove, cooperates with the outer wall of concave spherical clamping block 3, cavity side has square opening 13, and convex spherical clamping block 2 and concave spherical clamping block 3 can be passed through and installed.The convex spherical clamping block 2 and the concave spherical clamping block 3 are matched with each other, and are assembled in the end cavity of fixture main body 1, for clamping high temperature endurance sample 4.
[0032] The cavity is cylindrical cavity, square opening 13 is penetrated through the cavity side, and the bottom is equipped with through slot 14, for the end of sample 4 to be examined to be penetrated into cavity inside from side.The middle part of through slot 14 is through hole 15 with diameter slightly larger than slot width, for increasing the freedom degree of sample 4 swinging in all directions in through hole.
[0033] As an alternative embodiment, the sum of stress area of the minimum cross section of the cavity at the bottom end of fixture main body 1 should be twice or more than the working section area of the sample 4 to be examined, to ensure that fixture main body 1 has sufficient bearing capacity and will not be deformed or broken during work.
[0034] As an alternative embodiment, the material of fixture main body 1 can be selected from high-strength high-temperature alloy materials, for example, equiaxed crystal high-temperature alloy, directional crystallization high-temperature alloy and single crystal high-temperature alloy, which can withstand temperatures of 1000 DEG C, more preferably 1100 DEG C or higher.
[0035] The convex spherical clamping block 2 is symmetrically arranged in two blocks, without left and right distinction, and is assembled in the cylindrical cavity at the bottom of the clamp body 1 in cooperation with the concave spherical clamping block 3. The outer edge of the convex spherical clamping block 2 is a spherical surface (1 / 4 convex spherical surface for each block), and the inner side is a conformal groove for cooperation with the end of the sample 4, for clamping the sample 4 and transmitting the test stress to the sample 4.
[0036] The concave spherical clamping block 3 is symmetrically arranged in two blocks, without left and right distinction, and is assembled in the cylindrical cavity at the bottom of the clamp body 1 in cooperation with the convex spherical clamping block 2. The outer side of the concave spherical clamping block 3 is a cylindrical surface (1 / 2 cylindrical surface for each block), and the inner side is a spherical surface (1 / 4 concave spherical surface for each block). The cylindrical surface is used for cooperation with the cylindrical cavity at the bottom of the clamp body 1, and the inner side concave spherical surface is used for cooperation with the convex spherical surface of the convex spherical clamping block 2. The concave spherical clamping block 3 is provided with a cylindrical opening 31 at the bottom, which is larger than the diameter of the working section of the sample 4 and smaller than the diameter of the end of the sample 4, for the working section of the sample 4 to pass through.
[0037] As an optional embodiment, the concave spherical clamping block 3 and the convex spherical clamping block 2 can be made of high compressive strength high-temperature resistant ceramic materials, which are required to have smooth surfaces and small friction between the concave and convex spherical surfaces, and can freely slide relative to each other. As an example, zirconia / alumina / silicon carbide / aluminum nitride / silicon nitride and other ceramic materials can be used, and the compressive strength is preferably above 1800 MPa.
[0038] The use method of the embodiment is as follows. First, the threaded end of the clamp body 1 of the present application is connected with the pull rod of the testing machine, and then one of the concave spherical clamping block 3 and the convex spherical clamping block 2 is assembled and inserted into the cylindrical cavity from the cavity side opening at the other end of the clamp body 1. Then the end of the sample 4 to be tested is inserted into the cavity from the cavity side opening and the bottom slot 14, and the other pair of the concave spherical clamping block 3 and the convex spherical clamping block 2 is assembled and inserted into the cylindrical cavity. Finally, the concave spherical clamping block 3 and the convex spherical clamping block 2 are assembled with the sample 4 to be tested in the cavity. The included angle between the split lines of the pair of concave spherical clamping blocks 3 and the split lines of the pair of convex spherical clamping blocks 2 after assembly is 90°, and the structure after assembly is as shown in Figure 5 、 6 .
[0039] The above merely describes preferred embodiments of the present application and is not intended to limit the present application. The present application extends to any novel one, or any new combination, of the characteristics disclosed in the present specification and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application. It is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and that the details of the embodiments not disclosed, such as specific structures, are all prior art, and those skilled in the art can obtain them from the prior art. The connection mode can be fixed connection, detachable connection or integral; it can be fixed connection, movable connection or hinged connection, it can be directly connected or indirectly connected through an intermediate medium. For ordinary skilled in the art, the specific mode of the above terms in the embodiments of the present application can be understood according to the specific circumstances, and the embodiments of the present disclosure do not make specific limitations.
Claims
1. A fixture for high temperature endurance testing, characterized by: It includes a fixture body, a convex spherical clamping block and a concave spherical clamping block; the top of the fixture body is provided with a connecting structure for connecting to the testing machine pull rod, and the lower part of the fixture body is provided with a cavity structure; the cavity structure is provided with a convex spherical clamping block and a concave spherical clamping block for clamping the sample, and the convex spherical clamping block and the concave spherical clamping block can rotate relative to each other.
2. The clamp according to claim 1, wherein: The connection structure of the clamp body is a threaded section used to form a threaded connection with the pull rod of the endurance testing machine.
3. The clamp according to claim 1, wherein: The outer edge of the bottom of each convex spherical clamp is a convex spherical surface, and the inner side of the top of the convex spherical clamp is provided with a conformal groove that cooperates with the end of the sample; the inner side of the top of each concave spherical clamp is a concave spherical surface, and the concave spherical surface cooperates with the bottom of the convex spherical clamp.
4. The clamp according to claim 1, wherein: The cavity structure of the clamp body is a cylindrical cavity, and the cylindrical cavity is provided with a square opening passing through the side. The convex spherical clamping block and the concave spherical clamping block can pass through the square opening and be installed in the cylindrical cavity. The bottom of the cylindrical cavity is provided with a groove passing through in the radial direction, and the groove is connected with the square opening and the cylindrical cavity; the concave spherical clamping block and the convex spherical clamping block are both provided with a cylindrical opening for passing the sample.
5. The clamp according to claim 4, wherein: A through hole with a diameter greater than the slot width is provided in the middle of the slot; the diameter of the cylindrical opening of the concave spherical clamping block is greater than the diameter of the sample working section and smaller than the diameter of the sample end.
6. The clamp according to claim 4, wherein: The bottom of the cylindrical cavity is provided with a slot for docking with the bottom of the concave spherical clamping block, and the convex spherical clamping block is docked above the concave spherical clamping block.
7. The clamp according to claim 1, wherein: The convex spherical clamping block includes at least two pieces of the same shape that are spliced into one piece, and / or the concave spherical clamping block includes at least two pieces of the same shape that are spliced into one piece.
8. The clamp according to claim 7, wherein: The joint seams of the convex spherical clamping blocks and the joint seams of the concave spherical clamping blocks are arranged alternately.
9. The clamp according to claim 1, wherein: The clamp body is made of high-temperature resistant alloy.
10. The clamp according to claim 1, wherein: The convex spherical surface clamping block and the concave spherical surface clamping block are made of high-temperature resistant ceramic material.