CN103674694A - Long-time creep fixture - Google Patents

Abstract

The present invention is a durable creep fixture, comprising: a columnar fixture main body for connecting with a testing machine and carrying tensile load from the testing machine, the main body of the fixture has an outer surface in a circular arc on both sides of the radial direction The column (1) of the section, the inner surface of the column (1) is a plane perpendicular to the radial direction, the upper end of the column (1) is connected with the upper cover (2) of the fixture body, and the upper part of the upper cover (2) is a The solid cylinder (3) connected with the testing machine, the lower end of the column (1) is connected with the ring body (4) at the bottom of the fixture main body; two seat covers with the same structure in the shape of an arc segment, the seat cover has an arc The larger arc-shaped upper edge (5) of the section radius, the smaller arc-shaped lower edge (6) of the arc segment radius, the upper and lower arc-shaped upper edges (5) and the arc-shaped lower edges (6) Staggered, the two are connected by an arc-shaped cylinder, so that the longitudinal section of the seat cover is in a "zigzag"shape; it prevents the bonding between the fixture and the sample, realizes uniform loading and is conducive to reducing the test cost.

Description

A permanent creep fixture

technical field

The invention is a durable creep fixture, which belongs to the technical field of mechanical performance testing.

Background technique

As we all know, durability and creep are used to describe the performance of materials to withstand constant load for a long time under high temperature conditions. In order to obtain the durability and creep strength of the material, the material should be processed into a durability and creep specimen and loaded into a durability and creep testing machine for durability and creep testing. Endurance and creep testing machines are generally equipped with clamps for securing the specimens to the testing machine.

Between conventional permanent and creep specimens and fixtures, threaded connections are usually used to evenly transfer the applied load to the working section of the specimen through the threads. However, there is a problem of high temperature bonding in this threaded connection. That is, when the test is loaded for a long time at a temperature above about 900°C, due to the interdiffusion of atoms on the surface of the fixture and the sample under high-temperature loading, the fixture and the sample are bonded together by threads. This bonding results in the inability to separate the grips from the specimen after testing, resulting in scrapping the grips and significantly increasing the cost of testing.

In order to overcome the above-mentioned problem of bonding between the clamp and the sample, a shoulder-type clamp connection method has been disclosed. This shoulder type connection method has the problem of uneven stress. The inhomogeneity of the force leads to the imbalance of the loading coaxiality, which leads to a large difference in the measurement count of the extensometer and deviates from the actual deformation of the sample. This uneven stress causes uneven deformation of the fixture after a certain period of time in the test, and thus aggravates the stress unevenness of the sample in subsequent tests. In addition, the fixture replacement caused by the deformation of the fixture also increases the test cost.

Contents of the invention

Aiming at the above-mentioned problems in the prior art, the present invention proposes a permanent creep fixture, the purpose of which is to prevent the adhesion between the fixture and the sample, realize uniform loading and help reduce the test cost.

The purpose of the present invention is achieved through the following technical measures:

The permanent creep clamp is characterized in that the clamp includes:

A cylindrical fixture main body used to be connected with the testing machine and bear the tensile load from the testing machine, the main fixture main body has a column (1) whose outer surface is a circular arc segment on both sides of the radial direction, and the column (1) The inner surface is a plane perpendicular to the radial direction. The upper end of the column (1) is integrated with the upper cover (2) of the fixture body. The upper part of the upper cover (2) is a solid cylinder (3) connected with the testing machine. The column The lower end of (1) is connected into one body with the ring body (4) at the bottom of the fixture main body;

Two seat covers in the shape of arc segments with the same structure, the seat covers have an arc-shaped upper edge (5) with a larger radius of the arc segment, and an arc-shaped lower edge (6) with a smaller radius of the arc segment. The shaped upper edge (5) and the arc-shaped lower edge (6) are staggered up and down, and the two are connected by an arc-shaped cylinder (7), so that the longitudinal section of the seat cover is in the shape of a "zigzag";

Two arc-shaped seat covers are installed on the torus (4) between the columns (1) of the fixture main body, and the two ends of the arc-shaped upper edge (5) and the arc-shaped lower edge (6) are respectively connected to the The inner surface of the column (1) is attached, the outer surface of the arc-shaped cylinder (7) is attached to the inner surface of the torus (4), and the gap between the arc-shaped upper edge (5) and the torus (4) Secure the connection with pins (8).

The fixture main body, seat cover and pin (8) are all made of superalloy.

During the working process, the two ends of the arc-shaped upper edge (5) and the arc-shaped lower edge (6) are attached to the inner surface of the column (1) respectively, so that the clamp is passed through the bottom of the arc-shaped upper edge (5). The force exerted by the main body is transmitted to the arc-shaped lower edge (6) through the arc-shaped cylinder (7) of the seat cover, and the arc-shaped lower edge (6) is in contact with the lower surface of the shoulder of the sample (9).

The advantage of the technical solution of the present invention is that the fixture of the present invention can make the loaded surface of the sample carry a uniform load, thereby avoiding the failure of test data caused by uneven force during the test process. Additionally, the seat cover is a relatively small, inexpensive to manufacture component compared to the clamp body. Since the seat cover replaces the fixture body as the main component of the fixture damage during the test, the replacement of the fixture body can be avoided by only replacing the seat cover, thereby greatly reducing the test cost. And, through the fixing effect of the pin, the surface contact can be maintained all the time.

In addition to being applicable to endurance and creep tests, the invention is also applicable to the connection of other high-temperature long-term constant-load connection components.

According to the compact durable creep fixture of the present invention, the durable creep test with more accurate test results and lower cost can be realized.

Description of drawings

Fig. 1 is the front sectional view of the embodiment of the clamp in the state of being in cooperation with the sample of the present invention

Figure 2 is a sectional view taken along the line B-B line in Figure 1

Fig. 3 is the front sectional view of the seat cover of the embodiment of the present invention

Figure 4 is a top view of Figure 3

Detailed ways

The technical solution of the present invention is described in further detail below with reference to the accompanying drawings and embodiments:

As shown in Figures 1 to 4, the fixture includes:

A cylindrical jig body used to connect with the testing machine and bear the tensile load from the testing machine. The jig body has a column 1 whose outer surface is a circular arc segment on both sides of the radial direction, and the inner surface of the column 1 is vertical. In the radial plane, the upper end of the column 1 is integrated with the upper cover 2 of the fixture body. The upper part of the upper cover 2 is a solid cylinder 3 connected to the testing machine, and the lower end of the column 1 is connected to the ring body 4 at the bottom of the fixture body. Connected into one body, the inner edge surface of the torus 4 is tangent to the inner surface of the column 1;

Two arc-shaped seat covers with the same structure, the seat cover has an arc-shaped upper edge 5 with a larger radius of the arc segment, an arc-shaped lower edge 6 with a smaller radius of the arc segment, and an arc-shaped upper edge 5 It is staggered up and down with the arc-shaped lower edge 6, and the two are connected by an arc-shaped cylinder 7, so that the longitudinal section of the seat cover is in the shape of a "zigzag";

Two arc-shaped seat covers are installed on the ring body 4 between the columns 1 of the fixture main body, and the two ends of the arc-shaped upper edge 5 and the arc-shaped lower edge 6 are respectively attached to the inner surface of the column 1, The outer surface of the arc-shaped cylinder 7 is attached to the inner surface of the torus 4 , and the arc-shaped upper edge 5 and the torus 4 are fixedly connected by pins 8 .

During the test, the two ends of the sample 9 are respectively clamped by the above two sets of clamps at the upper and lower positions, and a load is applied. The load borne by the clamps is evenly distributed on the main body of the clamp, and the pin 8 can make the arc-shaped upper edge 5 and the circular arc The stress state of the contact surfaces between the ring bodies 4 is always kept evenly distributed.

The clamp body, seat cover and pin 8 are made of equiaxed crystal superalloy, directional crystal superalloy and single crystal superalloy, which can withstand the temperature above 1000°C.

Compared with the prior art, the technical solution of the present invention maintains a stress distribution state that is substantially similar to and obviously lower than the stress on the working section of the sample during the long-term test process for each component part of the fixture. Therefore, the component replacement cycle of the fixture is obviously extended, the performance test accuracy of the material is improved, and the problem of high-temperature bonding of the threaded connection fixture is overcome.

Claims (2)

1. A permanent creep clamp, characterized in that: the clamp comprises: A cylindrical fixture main body used to be connected with the testing machine and bear the tensile load from the testing machine, the main fixture main body has a column (1) whose outer surface is a circular arc segment on both sides of the radial direction, and the column (1) The inner surface is a plane perpendicular to the radial direction. The upper end of the column (1) is integrated with the upper cover (2) of the fixture body. The upper part of the upper cover (2) is a solid cylinder (3) connected with the testing machine. The column The lower end of (1) is connected into one body with the ring body (4) at the bottom of the fixture main body; Two seat covers in the shape of arc segments with the same structure, the seat covers have an arc-shaped upper edge (5) with a larger radius of the arc segment, and an arc-shaped lower edge (6) with a smaller radius of the arc segment. The shaped upper edge (5) and the arc-shaped lower edge (6) are staggered up and down, and the two are connected by an arc-shaped cylinder (7), so that the longitudinal section of the seat cover is in the shape of a "zigzag"; Two arc-shaped seat covers are installed on the torus (4) between the columns (1) of the fixture main body, and the two ends of the arc-shaped upper edge (5) and the arc-shaped lower edge (6) are respectively connected to the The inner surface of the column (1) is attached, the outer surface of the arc-shaped cylinder (7) is attached to the inner surface of the torus (4), and the gap between the arc-shaped upper edge (5) and the torus (4) Secure the connection with pins (8). 2. The permanent creep clamp according to claim 1, characterized in that: the clamp body, the seat cover and the pin (8) are all made of superalloy.

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