CN108225899A - With the composite thin plate drawing by high temperature test fixture and method from alignment function - Google Patents

Abstract

The present invention relates to a kind of composite thin plate drawing by high temperature test fixture and method having from alignment function, including hanging joint, collet, extension bar, snap ring, supporting block and protective frame；Upper and lower extension bar is connected by flexural pivot face with hanging joint, and two hanging joints are separately fixed on testing machine lower and upper cross-member；Each collet sets two supporting blocks in sample thickness direction front and rear surfaces, can be clamped by snap ring.The test fixture is connected by two flexural pivots with testing machine, can realize the automatic centering of extension test.Meanwhile snap ring under the effect of gravity can automatic clamping sample, and during sample heating and cooling thickness change realize automatic adjustment stablize clamping force.In addition, installing protective frame before on-test can accurately fix fixture collet up and down before testing machine is connected to, play the role of protecting thin sample.

Description

Composite thin plate high temperature tensile test fixture and method with self-centering function

technical field

The invention relates to a composite material thin plate high-temperature tensile test fixture and method with self-centering function, belonging to the high-temperature test field of composite materials.

Background technique

Composite materials have the advantages of high specific strength and specific stiffness, and designable mechanical properties. They are used in aerospace vehicles and engine hot-end parts, which can improve engine performance and reduce weight. Composite materials, such as ceramic matrix composites, are often used in high-temperature components to withstand loads at high temperatures. Therefore, it is necessary to test the mechanical properties of composite materials at high temperature, and high temperature tensile testing of composite materials is a necessary experimental means to test their mechanical properties.

Referring to the high-temperature tensile test standard ASTM C1359 for ceramic matrix composites, due to the brittleness of ceramic matrix composites, the contact part between the fixture and the sample must be a flat and uniform surface, not point contact or line contact. Fixtures can be roughly divided into two categories: active clamping contact surface and passive clamping contact surface. Grips that actively clamp the contact surface require mechanical, hydraulic, or pneumatic power to clamp the sample, and additional devices are required to provide pressure perpendicular to the surface of the sample and generate friction on the contact surface between the sample and the fixture to clamp the sample. Sample. Passive clamping contacts transfer force directly to the specimen through a mechanical connection, such as a shoulder or hole. For thin plates, openings can cause stress concentrations that can lead to failure of the specimen. In addition, if the holes are opened and fixed by pins, the pins will be easily deformed under high temperature, resulting in inconvenient assembly and disassembly.

Contents of the invention

The present invention provides a composite sheet high-temperature tensile test fixture and method with a self-centering function in view of the above-mentioned problems. Snap ring 6, upper support block 2, lower support block 5, chuck 1 and sample 4;

The hanging joint 9 includes an upper hanging joint and a lower hanging joint, and the upper and lower hanging joints have the same structure; the joints of the upper hanging joint and the lower hanging joint are designed with a concave spherical surface 19, and the radius of the spherical surface is determined according to the design load of the fixture. A cooling water nozzle 20 is designed, and the hanging joint 9 is fixed on the testing machine;

The connecting rod 8 includes an upper connecting rod and a lower connecting rod, and the upper and lower connecting rods have the same structure; one end 21 of the connecting rod is a convex spherical surface, and its size is the same as the radius of the concave spherical surface 19 of the hanging joint. Concave and convex spherical surfaces 19, 21 form a spherical joint to connect; the other end of the connecting rod is an external thread 22, and a pair of wrench operating planes 23 are provided near the external thread, and the length of the extending section 24 of the connecting rod is determined according to the size of the high-temperature furnace , it is necessary to ensure that the convex spherical surface 21 is outside the high-temperature furnace;

The collet 1 includes an upper collet and a lower collet, the upper and lower collets have the same structure, the internal thread hole 25 of the collet 1 is screwed and connected with the external thread 22 of the post 8, and the collet 1 and the post 8 are Split type, easy to replace the chuck according to different styles; the outer cylindrical surface of the chuck away from the clamping end is provided with a chuck positioning plane 11 on the right side;

The upper support block 2 includes an upper support block top 12 and an upper support block bottom 13, the upper support block top 12 is square, the left and right end faces are planes, and the upper support block bottom 13 left and right end faces are arc surfaces; Lower support block 5 comprises lower support block top 14 and lower support block bottom 15, and lower support block top 14 left and right end faces are circular arc surfaces, and lower support block bottom 15 is square, and left and right end faces are plane; Upper support block 2 Form an inverted T shape with the lower support block 5 respectively, and two groups fit the front surface and the rear surface of the sample 4 respectively, and the left and right circular arc end faces are flush with the sample.

When the sample is loaded, the upper support block 2 and the lower support block 5 are placed inside the chuck 16, and the cross-sectional shape of the upper support block 2 and the lower support block 5 fits with the shape of the chuck inner 16 to realize the connection between the support block and the clamp. Mutual positioning of the heads; along the thickness direction of the sample, the 13 arc parts of the lower part of the upper support block are thickened, and the 15 square parts of the lower support block are thickened. The angle between the fitting surface is 3-6°) The inclined surface gradually thickens, and finally forms a wedge shape with a narrow top and a wide bottom;

The upper snap ring 3 and the lower snap ring 6 are all in an inverted U shape, and the inner surfaces of the upper and lower snap ring inner walls 17, 18 gradually change from top to bottom according to the same slope angle as the upper support block bottom 13 and the lower support block bottom 15. Thinning; under the state of loading the sample, the upper and lower snap rings press and fix the inner walls 17, 18 of the upper and lower snap rings respectively to fix the lower part 13 of the upper support block and the lower part 15 of the lower support block through the action of gravity; while the upper and lower snap rings The hollow cylindrical parts 27 and 28 on the upper part of the ring fit with the outer cylindrical surface 26 below the chuck, thereby realizing the mutual positioning of the snap ring and the chuck, and then using the support block to realize the positioning of the sample in the front and rear directions inside the chuck 16 .

The upper and lower snap rings 3 and 6 can not only automatically clamp the sample 4 by gravity, but also automatically balance the clamping force according to the test temperature. When the temperature of the sample 4 and the support block rises, the sample 4 and the upper and lower support blocks The total thickness of 2 and 5 will increase, and the upper and lower snap rings 3 and 6 will move upward relative to the support block to automatically balance the clamping force in the thickness direction.

The protective frame 7 is composed of a connecting rod 29, two cross bars 30 with identical structures and K-type hand-tightened nuts 31. Assembled the protective frame 7, the upper part 10a of the positioning surface of the protective frame of the two cross bars and the lower part 10b of the positioning surface of the protective frame are on a plane.

The protective frame 7 is installed on the chuck 1 before the test starts, when the sample is not loaded; by unscrewing the K-shaped hand-tightened nut 31, the half ring 32 is opened, the cross bar 30 can be inserted into the chuck 1, and then locked K Type thumb nut 31. The positioning surface 10 of the protective frame and the positioning plane 11 of the chuck are positioned in cooperation with each other, and the circumferential positioning of the upper and lower chucks is realized by means of the upper part 10a of the positioning surface of the protective frame and the lower part 10b of the positioning surface of the protective frame.

The upper and lower chucks 1, and the connecting rod 8 screwed and fixedly connected with the chuck 1 form a whole through the loaded protective frame 7. In this state, the sample 4, the upper and lower support blocks 2, 5 and the upper and lower support blocks are installed. Snap rings 3 and 6, then put the overall fixture into the concave spherical surface 19 inside the hanging joint 9 installed on the testing machine through the convex spherical surface 21 of the connecting rod 8, raise the beam of the testing machine, and when the upper and lower concave-convex spherical hinge surfaces just start to contact, turn Open the K-type thumb nut 31, open the half ring 32, and take off the protective frame 7. The protective frame is installed on the fixture before the test starts to protect the sample. After the fixture is installed, the fixture can be moved and installed on the testing machine through the protective frame. When the test starts, it can be removed to ensure the safety of the installation. precision.

During the test, even if there is a deviation in the orientation and angle of the upper and lower joints 9 of the testing machine so that the displacement and force loading are not on a vertical line, the existence of the ball joint surface of the extension rod can also realize the self-centering of the upper and lower chucks during the test , to ensure the accuracy of the test results.

In the high temperature tensile test of the composite material, the shape of the sample is dumbbell-shaped, including two clamping sections 33 , two transition sections 34 and an intermediate gauge section 35 . The left and right end faces of the transition section 34 are arc-shaped.

The concrete installation method of described fixture is:

1) Put one of the two upper support blocks into the slot of the upper chuck, install the clamping section of the sample close to the upper support block, and then put the other of the two upper support blocks into the compression sample clamping section.

2) The upper clasp is inserted from the upper end of the upper chuck, clamps the upper support block under the action of gravity, and positions the sample in the upper chuck.

3) First put the lower snap ring into the sample from the lower end of the sample, temporarily fix it on the upper chuck, then carefully put the lower end of the sample into the lower chuck, install the protective frame on the upper and lower chucks, and position the upper and lower chucks. , Lower chuck.

4) The lower support block is loaded into the slot of the lower chuck from both sides of the sample, and installed close to the lower clamping section of the sample, and the lower snap ring loaded before is released from the position close to the upper chuck, and clamped under the action of gravity The lower support block is used to position the sample in the lower chuck.

5) Properly lower the beam of the testing machine, install the overall upper and lower fixtures fixed by the protective frame into the hanging joint installed on the testing machine, first make the convex spherical surface of the upper connecting rod fit into the concave spherical surface of the upper hanging joint, and the lower end of the lower connecting rod Insert the lower end of the lower joint, and slowly raise the beam of the testing machine, so that the lower end of the lower rod and the concave-convex spherical surface of the lower joint just begin to contact.

6) According to the test requirements, adjust the circumferential positions of the overall upper and lower fixtures so that one surface of the sample faces the observation lens.

7) Unscrew the K-type hand-tightened nut, open the half-ring of the cross bar of the protective frame, and remove the protective frame 7. Ready to start experimenting.

All parts of the fixture except sample 4 are made of high-temperature-resistant and high-strength materials, which can be high-temperature alloys or ceramic materials, so that the fixture can meet the high-temperature conditions of the test.

The beneficial effects of the present invention are:

The connecting rod is connected with the testing machine through a ball joint, which can realize the automatic centering of the upper and lower fixtures during the tensile test. A support block is added in the thickness direction of the sample, which can effectively prevent the buckling of the thin plate sample when the circular arc end face of the sample is loaded, and ensure stable clamping. At the same time, the clasp can automatically clamp the sample under the action of gravity, and as the temperature rises, the volume of the sample and the support block expands, and the clasp automatically balances the clamping force. The collet is connected to the rod through thread, which can be easily replaced according to different sample specifications. In addition, the protective frame is temporarily installed before the test, which can well protect the thin plate sample from damage during the clamping process.

Description of drawings

Figure 1 is a schematic diagram of the fixture assembly.

Fig. 2 is a schematic diagram of the cross bar of the protective frame.

Fig. 3 is a schematic diagram of the three-dimensional structure of the protective frame.

Figure 4 and Figure 5 are schematic diagrams of the chuck structure.

Fig. 6 is a schematic diagram of the structure of the hanging joint.

Fig. 7 is a schematic diagram of the connecting rod structure.

Fig. 8 is a schematic diagram of the structure of the upper support block.

Fig. 9 is a schematic diagram of the structure of the lower support block.

10, 11 and 12 are schematic diagrams of the structure of the upper snap ring.

13, 14, 15 are schematic diagrams of the structure of the upper clasp.

Figure 16 is a schematic diagram of the sample structure.

The symbols in the figure are explained as follows:

chuck 1; upper support block 2; upper snap ring 3; sample 4; lower support block 5; lower snap ring 6;

Protective frame 7; connecting rod 8; hanging joint 9; protective frame positioning surface 10; protective frame positioning surface upper part 10a;

The lower part 10b of the positioning surface of the protective frame; the positioning plane 11 of the chuck; the upper part 12 of the upper support block;

The lower part of the upper support block 13; the upper part of the lower support block 14; the lower part of the lower support block 15; the inside of the chuck 16;

Upper snap ring inner wall 17; lower snap ring inner wall 18; concave spherical surface 19; cooling nozzle 20; convex spherical surface 21;

External thread 22; wrench operating plane 23; rod extension 24; internal threaded hole 25; outer cylindrical surface 26;

The upper snap ring hollow cylindrical part 27; the lower snap ring hollow cylindrical part 28; the connecting rod 29; the cross bar 30;

K-type hand screw nut 31; half ring 32; clamping section 33; transition section 34; middle gauge section 35;

Detailed ways

Below in conjunction with a specific case in the accompanying drawings the present invention will be described in further detail:

As shown in Figure 1: a fixture for high-temperature tensile testing of composite material plates, including a hanging joint 9, a connecting rod 8, a protective frame 7, an upper snap ring 3, a lower snap ring 6, an upper support block 2, and a lower support Block 5, chuck 1 and sample 4, etc. The hanging joint 9 is fixed on the testing machine, the connecting rod 8 and the hanging joint 9 are connected by a spherical hinge formed by concave and convex spherical surfaces 19 and 21, and the chuck 1 is screwed and connected with the external thread 22 of the connecting rod 8 through the inner threaded hole 25 of the chuck , the upper support block 2 and the lower support block 5 are respectively attached to the surface of the sample 4 and placed inside the chuck 1, and are respectively clamped by the upper and lower snap rings 3 and 6. The protective frame 7 is before the test, and the sample is not installed. It is installed on chuck 1 when it is inserted, and it is removed before the test starts.

In the high-temperature tensile test of composite materials, the shape of the sample is shown in Figure 16. The sample is dumbbell-shaped and includes two clamping sections 33 , a transition section 34 and an intermediate gauge section 35 . The transition section is arc-shaped. For composite material samples, usually its thickness should not be less than 3mm, but the tensile test of ultra-thin samples with a sample thickness of 1mm to 3mm can be performed using this fixture system. The cross-sectional area of the gauge section should not be too small. According to the accuracy requirements of the relevant testing machine, it is suggested that the width of the gauge section should not be less than 10mm. The larger the width of the clamping section, the larger the load-bearing area of the arc section, and the more effective it can be to improve the local pressure situation. However, due to the size limitation of the high-temperature furnace cavity, it is recommended that the width of the clamping section be between 20-25mm. If the radius of the arc section is too small, the dangerous area of the sample is small, the location is concentrated, and it is easy to break at the interface. When the ratio of the arc radius to the width of the gauge section is not less than 2.5, the size of the dangerous area gradually tends to be stable. That is, the probability of obtaining the expected failure mode is greatly increased. When the aspect ratio of the gauge length section is not less than 3, the gauge length section can obtain a uniform stress distribution. When the ratio of the length of the clamping section to the width of the gauge section is not less than 2, the effect of the length of the clamping section on stress concentration tends to be stable. Therefore, it is recommended that the ratio of the radius of the arc to the width of the gauge section be greater than or equal to 2.5, and the ratio of the aspect ratio of the gauge section and the length of the clamping section to the width of the gauge section be greater than or equal to 2.0.

Both the upper support block 2 in Fig. 8 and the lower support block 5 in Fig. 9 have two pieces, two in a group, which respectively fit the front and back surfaces of the sample 4, and the left and right arc end surfaces are flush with the sample. The size of the arc surface of the lower part 13 of the upper support block and the upper part 14 of the lower support block is determined by the transition section 34 of the sample; The length and width of the clamping section 33 surface are about 1mm larger; the slope of the thickened part of the upper and lower support blocks 2 and 5 and the angle between it and the sample bonding surface are between 3-6°.

Fig. 4 and Fig. 5 are the schematic structural diagrams of the chuck 1, the inner 16 of the chuck fits the cross-sectional shape of the upper support block 2 and the lower support block 5, and the size of the cross-section can be determined by the upper and lower support blocks 2 and 5; The threaded hole 25 matches the external thread 22 of the connecting rod 8; the collet 1 is provided with a collet positioning plane 11 on the outer cylindrical surface away from the clamping section, and the collet positioning plane 11 is about 1mm away from the outer surface of the original cylindrical surface.

The upper snap ring 3 in Fig. 10, Fig. 11 and Fig. 12, and the lower snap ring 6 of Fig. 13, Fig. 14, Fig. 15, the inner walls 17, 18 of the upper and lower snap rings are pressed and fixed respectively on the lower part 13 and the lower part of the upper supporting block. The lower part 15 of the support block, the upper hollow cylindrical parts 27, 28 of the upper and lower snap rings fit together with the outer cylindrical surface 26 below the chuck, and the hollow cylindrical part 27 of the upper snap ring is different in height from the hollow cylindrical part 28 of the lower snap ring, which is convenient for assembly Time zone upper and lower clasps.

Fig. 7 is a schematic structural view of the connecting rod 8. The external thread 22 at one end of the connecting rod is tightly connected with the internally threaded hole 25 of the chuck, and a pair of wrench operating planes 23 are provided near the external thread. The length of the extending section 24 of the connecting rod is Determined by the size of the high-temperature furnace, to ensure that the convex spherical surface 21 at the other end of the connecting rod is outside the high-temperature furnace.

Fig. 6 is a schematic structural diagram of the hanger joint 9. A cooling nozzle 20 is designed above the joint. The concave spherical surface 19 of the hanger joint 9 and the convex spherical surface 21 of the connecting rod form a spherical joint structure, and the radius of the spherical surface is determined according to the design load of the fixture. Fig. 2 and Fig. 3 are the structural representations of the protective frame 7, which are composed of a connecting rod 29, two cross bars 30 and K-type thumb nuts 31 with the same structure. Before the test starts, the sample is installed on the chuck 1 when it is not loaded; by unscrewing the K-type thumb nut 31 and opening the half ring 32, the cross bar 30 can be inserted into the chuck 1, and then the K-type thumb nut is locked 31. The upper part 10a of the protective frame positioning surface and the protective frame positioning surface 10b of the two cross bars 30 cooperate with the chuck positioning plane 11, and the circumferential positioning of the upper and lower chucks can be realized by means of the upper part 10a of the protective frame positioning surface and the protective frame positioning surface 10b.

Parts not described in detail in the present invention belong to the well-known technology in the art.

The above are only part of the specific implementation methods of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily imagined by those skilled in the art within the technical scope disclosed in the present invention should be covered within the protection scope of the present invention.

Claims (10)

1. a kind of composite thin plate drawing by high temperature test fixture having from alignment function, it is characterised in that：The test fixture Including hanging joint, extension bar, protective frame, upper snap ring, lower snap ring, upper supporting block, lower supporting block, collet and sample；

The hanging joint includes upper hanging joint and lower hanging joint, and upper and lower mounting header structure is identical；Upper hanging joint and lower hanging joint are hung The place of connecing is designed with concave spherical surface, and spherical radius is determined according to fixture design load, and cooling water nozzle, hanging joint are designed with above hitching position It is fixed on testing machine；

The extension bar includes upper extension bar and lower extension bar, upper and lower connection rod structure are identical；Extension bar one end is convex spherical, and size is with hanging Radius at connector concave spherical surface is identical, and extension bar forms flexural pivot by concave, convex spherical surface with hanging joint and is connected；The extension bar other end is outer Screw thread, and it is being equipped with a pair of of spanner operation planar close to the externally threaded position；Extension bar extends segment length according to high temperature furnace size It determines, need to ensure convex spherical outside high temperature furnace；

The collet includes upper grip and lower collet, and upper and lower chuck structure is identical, the internal thread hole of collet and the external screw thread of extension bar Screw connection；Collet is split type with extension bar, convenient for carrying out the replacement of collet according to different patterns；Collet is outer far from bare terminal end Cylindrical surface is equipped with a collet in directly to the right and positions plane；

The upper supporting block includes upper supporting block top and upper supporting block lower part, and upper supporting block top is square, in upper supporting block The left and right end face in portion is plane, and the upper left and right end face in supporting block lower part is arc surface；The lower supporting block includes lower supporting block top With lower supporting block lower part, the lower left and right end face in supporting block top is arc surface, and lower supporting block lower part is square, lower supporting block lower part Left and right end face is plane；Upper supporting block and lower supporting block respectively form inverted T-shaped, two one group, are bonded the front surface of sample respectively And rear surface, circular arc end face are flushed with sample；

The upper snap ring and lower snap ring are all inverted U shape, upper and lower snap ring inner wall inner surface from top to bottom according to upper supporting block lower part The bevel angle identical with lower supporting block lower part is gradually thinned；

The protective frame is made of a connecting rod, the identical cross bar of two root architectures and K-type hand nutting；Assembling finishes anti- Retaining frame, the protective frame positioning surface top and protective frame positioning surface lower part of two cross bars are in one plane.

2. the composite thin plate drawing by high temperature test fixture according to claim 1 having from alignment function, feature It is：Under sample loading state, upper supporting block and lower supporting block are placed on the section shape of collet interior, upper supporting block and lower supporting block Shape is bonded to each other with collet interior shape, realizes being mutually located for supporting block and collet；Along sample thickness direction, under upper supporting block Portion's circular arc portion thickeies, and lower supporting block lower part projected square part thickeies, and thickening mode is from top to bottom gradually added by constant inclined surface angle Thickness finally constitutes up-narrow and down-wide wedge shape；Bevel angle is at 3-6 °.

3. the composite thin plate drawing by high temperature test fixture according to claim 1 having from alignment function, feature It is：It is packed under sample state, upper and lower snap ring is fixed supporting block respectively by gravity, upper and lower snap ring inner wall Lower part and lower supporting block lower part；And upper and lower snap ring top hollow cylindrical part mutually agrees with external cylindrical surface below collet, realizes Snap ring and collet are mutually located, then by upper and lower supporting block, realize sample in collet interior positioning in the front-back direction.

4. the composite thin plate drawing by high temperature test fixture according to claim 1 having from alignment function, feature It is：Upper and lower snap ring and gravity Automatic-clamping sample can not only be passed through, additionally it is possible to according to test temperature autobalance clamping force, When the temperature of sample and supporting block increases, the overall thickness of sample and upper and lower supporting block can increase, and upper and lower snap ring can opposite support Block moves up, autobalance thickness direction clamping force.

5. the composite thin plate drawing by high temperature test fixture according to claim 1 having from alignment function, feature It is：Protective frame is mounted on when sample is not loaded on collet before on-test；By unscrewing K-type hand nutting, half is opened Ring, cross bar can be inserted in collet, then lock K-type hand nutting；It is fixed that protective frame positioning surface cooperates with collet positioning plane The circumferentially positioned of upper and lower collet is realized in position by protective frame positioning surface top and protective frame positioning surface lower part.

6. the composite thin plate drawing by high temperature test fixture according to claim 1 having from alignment function, feature It is：Upper and lower collet and to screw connected extension bar with collet integral by the protective frame shape of loading, pacifies in this case Sample, upper and lower supporting block and upper and lower snap ring are filled, then integral clamp by the convex spherical of extension bar is packed into and is mounted on experiment Concave spherical surface inside the hanging joint of machine increases testing machine crossbeam, when bumps flexural pivot face just starts contact up and down, unscrews K-type hand and twists Nut opens semi-ring, removes protective frame；Protective frame is mounted on before on-test on fixture, is protected sample, is entirely pacified in fixture After the completion of dress, fixture overall movement is installed on testing machine by protective frame, during on-test, then is dismantled, Neng Goubao Demonstrate,prove the accuracy of installation.

7. the composite thin plate drawing by high temperature test fixture according to claim 1 having from alignment function, feature It is：During experiment, to cause displacement and the loading of power even if there are deviations the orientation of hanging joint up and down and angle of testing machine Not on a vertical line, the presence in extension bar flexural pivot face can also realize that collet is during the experiment from centering up and down, it is ensured that experiment As a result accuracy.

8. the composite thin plate drawing by high temperature test fixture according to claim 1 having from alignment function, feature It is：Specimen shape is dumbbell shaped, including two gripping sections, two changeover portions and intermediate gauge length section；Changeover portion or so end face is It is arc-shaped.

9. the composite thin plate drawing by high temperature test fixture according to claim 1 having from alignment function, feature It is：The material that all parts of fixture are selected in addition to sample is high temperature resistant, high-strength material, including high temperature alloy, ceramic material Material.

10. a kind of composite thin plate drawing by high temperature test fixture according to claim 1 with from alignment function Installation method, which is characterized in that include the following steps：

Step 1：By in one of loading upper grip card slot of two upper supporting blocks, the gripping section of sample is close to supporting block Installation, then another loading of two upper supporting blocks is compressed into sample holder section；

Step 2：Upper snap ring is inserted in from upper grip upper end, clamps upper supporting block under the effect of gravity, positioning sample is in upper grip Position；

Step 3：Lower snap ring is first inserted in sample from sample lower end, is temporarily fixed to upper grip, is then put into down sample lower end Protective frame is installed on upper and lower collet by collet interior, positions upper and lower collet；

Step 4：Lower supporting block is fitted into down from sample both sides in collet card slot, is close to gripping section under sample and is installed, from close to upper folder The lower snap ring that the release of head position is packed into before clamps lower supporting block, positioning sample position in lower collet under the effect of gravity；

Step 5：Testing machine crossbeam is reduced, the mounting mounted on testing machine will be packed into through the upper and lower fixture of the fixed entirety of protective frame Head first makes the convex spherical of extension bar be packed into upper hanging joint concave spherical surface, and the lower hanging joint lower end of lower end merging of lower extension bar slowly increases Testing machine crossbeam makes lower extension bar lower end just start to contact with lower hanging joint concave, convex spherical surface；

Step 6：The whole upper and lower fixture circumferential position of adjustment makes one surface face observation camera lens of sample；

Step 7：K-type hand nutting is unscrewed, opens protective frame cross bar semi-ring, removes protective frame, preparation starts to test.