Surface contact clamp for tensile torsion of high-strength metal sample

Abstract

The utility model provides a surface contact fixture for tensile torsion of high-strength metal sample, which comprises a first fixture and a second fixture, a first clamping structure is formed on the first side surface of the first fixture, a second clamping structure is formed on the first side surface of the second fixture, the first clamping structure is provided with a first clamping surface, and the second clamping structure is provided with a second clamping surface. The first clamping structure is provided with a first clamping surface, the second clamping structure is provided with a second clamping surface, and the first clamping surface and the second clamping surface can form surface contact surrounding wrapping on the peripheral wall of the high-strength metal sample in the length direction of the high-strength metal sample when the surface contact clamp is used for a tensile torsion test. According to the utility model, the clamping force-applying contact area with the sample is increased, so that the clamping pressure can be uniformly distributed, the contact stress is effectively reduced, and the wire breakage probability of a clamping area caused by sample slipping, clamp bite and stress concentration in the stretching and twisting operation process is further effectively reduced.

Description

Surface contact clamps for tensile and torsional stresses of high-strength metal specimens Technical Field

[0001] This utility model belongs to the field of metal specimen tensile and torsion fixture design technology, specifically relating to a surface contact fixture for tensile and torsion of high-strength metal specimens. Background Technology

[0002] For ultra-high strength (>2000MPa) and ultra-fine (φ<3mm) wire samples, existing fixtures have problems such as excessively large clamping grooves for rod-shaped samples and small contact areas for plate samples. During stretching and torsion, the wire slips and breaks in the clamping area, which seriously hinders the torsion processing and performance testing of ultra-high strength wires. Summary of the Invention

[0003] Therefore, this utility model provides a surface contact fixture for tensile and torsion testing of high-strength metal specimens, which can overcome the technical problems in related technologies where the clamping of high-strength metal specimens is done by point contact or line contact, the clamping of the specimen is unreliable, stress concentration occurs, and slippage and stress concentration occur during the tensile and torsion test, or even the clamp bites the specimen.

[0004] To address the aforementioned problems, this utility model provides a surface contact fixture for tensile and torsion testing of high-strength metal specimens, comprising a first fixture and a second fixture. A first clamping structure is formed on a first side of the first fixture, and a second clamping structure is formed on a first side of the second fixture. The first clamping structure has a first clamping surface, and the second clamping structure has a second clamping surface. When the surface contact fixture is used for tensile and torsion testing, the first clamping surface and the second clamping surface can form a surface contact around the outer peripheral wall of the high-strength metal specimen along the length direction of the high-strength metal specimen.

[0005] In some embodiments, the first clamping structure is a first groove, which is formed on a first side of the first clamp and extends through to a first end face of the first clamp along the length of the high-strength metal sample, and the first clamping surface is the groove wall surface of the first groove. The second clamping structure is a second groove, which is formed on a first side of the second clamp and extends through to a first end face of the second clamp along the length of the high-strength metal sample, and the second clamping surface is the groove wall surface of the second groove.

[0006] In some embodiments, the first clamping structure includes a first groove and a first pad, the first groove being formed on a first side of the first clamp and extending through to a first end face of the first clamp along the length direction of the high-strength metal sample, the first pad being detachably assembled in the first groove, and the first clamping surface being the wall surface of the first pad away from the first groove. The second clamping structure includes a second groove and a second pad, the second groove being formed on a first side of the second clamp and extending through to a first end face of the second clamp along the length direction of the high-strength metal sample, the second pad being detachably assembled in the second groove, and the second clamping surface being the wall surface of the second pad away from the second groove.

[0007] In some embodiments, the mechanical strength of the first pad and the second pad is higher than that of the first clamp and the second clamp; and / or, the first pad and the first groove, and the second pad and the second groove are fixedly connected by a positioning structure; and / or, the openings of the first groove and the second groove at the first end face are rounded.

[0008] In some embodiments, the positioning structure includes a limiting protrusion and a limiting groove, wherein the limiting protrusion is formed on the wall surface of the first pad layer facing the first groove and the wall surface of the second pad layer facing the second groove, the limiting groove is located on the groove wall surface of the first groove and the second groove, and the limiting protrusion is embedded in the limiting groove.

[0009] In some embodiments, the limiting protrusion includes an axial protrusion and a circumferential protrusion that intersect, and the limiting groove includes an axial groove that matches and is fitted with the axial protrusion and a circumferential groove that matches and is fitted with the circumferential protrusion.

[0010] In some embodiments, the first end face is the side of the first and second clamps closest to the gauge length of the high-strength metal sample; the thickness of the first and second pads is h; and the thickness of the first and second clamps corresponding to the first end face is H, 0.1 mm. <h<H。

[0011] In some embodiments, the first end face is the side end face of the first clamp and the second clamp close to the gauge length of the high-strength metal sample, and the side end face of the first clamp and the second clamp opposite to the first end face is the second end face. In the direction from the second end face to the first end face, the mechanical strength of the first pad and the second pad decreases.

[0012] In some embodiments, the microVickers hardness of the first and second pads at positions corresponding to the second end face is Hv. HThe micro Vickers hardness of the positions corresponding to the first end face is Hv. L The microVickers hardness of the clamping section of the high-strength metal sample is Hv. sample Hv H >Hv sample Hv L >0.3Hv sample The yield strengths of the first and second cushion layers at the positions corresponding to the second end face are σ. H The yield strengths at the positions corresponding to the first end face are σ. L The tensile strength of the high-strength metal specimen is σ. sample , σ H >σ sample , σ L >0.3σ sample .

[0013] In some embodiments, the thickness of the first and second clamps gradually decreases from one end away from the gauge length of the high-strength metal specimen to the end near the gauge length, such that the side facing away from each other of the first and second clamps is an inclined plane; and / or, the first and second clamps are respectively provided with connection holes for connection to the testing equipment.

[0014] The surface contact fixture for tensile and torsional stress testing of high-strength metal specimens provided by this utility model has the following beneficial effects:

[0015] By forming a first clamping structure and a second clamping structure on the first clamp and the second clamp, the first clamping surface and the second clamping surface of the two clamping structures can be used to achieve surface contact and wrap around the outer peripheral wall of the metal sample, thereby increasing the contact area for clamping force with the sample and making the clamping pressure evenly distributed. This effectively reduces the contact stress, and thus effectively reduces the probability of wire breakage in the clamping area (i.e., outside the gauge length of the sample) caused by sample slippage, clamping damage, and stress concentration during tensile and torsion operations. Attached Figure Description

[0016] To more clearly illustrate the embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0017] Figure 1 is a three-dimensional structural schematic diagram of a surface contact fixture for tensile and torsional stress of high-strength metal specimens according to one embodiment of the present invention.

[0018] Figure 2 is a schematic diagram of the structure of the first / second cushion layer in Figure 1. The figure also shows the trend of the mechanical strength of the cushion layer from the distance from the gauge length of the sample to the distance from the gauge length (i.e., the orientation of the figure is from bottom to top).

[0019] The attached figures are labeled as follows:

[0020] 1. First clamp; 10. First clamping surface; 11. First groove; 2. Second clamp; 20. Second clamping surface; 21. Second groove; 31. First pad; 32. Second pad; 301. Axial protrusion; 302. Circumferential protrusion; 4. Connecting hole. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present utility model or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0022] In the description of this utility model, it should be understood that the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this utility model. The directional terms "inner" and "outer" refer to the inner and outer contours of each component itself.

[0023] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90° or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0024] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this utility model.

[0025] Referring to Figures 1 and 2, according to an embodiment of the present invention, a surface contact fixture for tensile and torsional stress on high-strength metal specimens is provided, comprising a first fixture 1 (e.g., a left fixture) and a second fixture 2 (e.g., a right fixture). A first clamping structure (not labeled) is formed on a first side of the first fixture 1, and a second clamping structure (not labeled) is formed on a first side of the second fixture 2. The first clamping structure has a first clamping surface 10, and the second clamping structure has a second clamping surface 20. Tension and / or torsion are performed on the surface contact fixture. During the rotation test, the first clamping surface 10 and the second clamping surface 20 can form a surface contact and surround the outer peripheral wall of the high-strength metal specimen along its length. It is understood that, assuming the high-strength metal specimen is cylindrical (e.g., a wire with a circular cross-section), the outer peripheral wall refers to its outer circumferential wall. When the high-strength metal specimen is a wire with a polygonal cross-section, the outer peripheral wall refers to a portion of each side surface excluding its two ends, and so on. The high-strength metal specimen refers to a metal specimen with a yield strength > 200 MPa.

[0026] In this technical solution, by forming a first clamping structure and a second clamping structure on the first clamp 1 and the second clamp 2, the first clamping surface 10 and the second clamping surface 20 of the two clamping structures respectively can achieve surface contact and wrapping around the outer peripheral wall of the metal sample, thereby increasing the contact area for clamping force with the sample and enabling uniform distribution of clamping pressure. This effectively reduces contact stress and, consequently, reduces the probability of wire breakage in the clamping area (i.e., outside the gauge length section of the sample) caused by sample slippage, clamping damage, and stress concentration during tensile and torsion operations. The clamps in this invention are particularly suitable for tensile operations on ultra-fine (φ≥0.1mm) and ultra-high strength (≥2100MPa) wires.

[0027] It is understood that the aforementioned first clamping surface 10 and second clamping surface 20 should be adapted to the outer peripheral wall of the metal sample to be clamped in terms of shape and size. For example, when the metal sample is a wire with a circular cross-section, the first clamping surface 10 and the second clamping surface 20 should have the same curvature as the outer peripheral wall of the wire. That is, the first clamping surface 10 and the second clamping surface 20 should both be arc-shaped walls with radii equal to the radius of the wire. In order to ensure reliable clamping of the metal sample, the circular angle corresponding to the projection of the first clamping surface 10 and the second clamping surface 20 on the tensile direction (i.e., the length direction, the axial direction) of the metal sample should not exceed 180°, and should be as large as possible within the aforementioned angle range, for example, it can be 170° to 179°.

[0028] In an embodiment not shown in the figure, the first clamping structure is a first groove 11, which is formed on the first side of the first clamp 1 and extends through to the first end face of the first clamp 1 along the length direction of the high-strength metal sample. The first clamping surface 10 is the groove wall surface of the first groove 11. The second clamping structure is a second groove 21, which is formed on the first side of the second clamp 2 and extends through to the first end face of the second clamp 2 along the length direction of the high-strength metal sample. The second clamping surface 20 is the groove wall surface of the second groove 21.

[0029] In this technical solution, the first clamping structure and the second clamping structure are directly formed as groove structures on the first clamp 1 and the second clamp 2, which can simplify the number of clamping parts and reduce the clamping design and production costs.

[0030] In another embodiment, as shown in Figures 1 and 2, the first clamping structure includes a first groove 11 and a first pad 31. The first groove 11 is formed on a first side of the first clamp 1 and extends through to the first end face of the first clamp 1 along the length direction of the high-strength metal sample. The first pad 31 is detachably assembled in the first groove 11. The first clamping surface 10 is the wall surface of the first pad 31 away from the first groove 11. The second clamping structure includes a second groove 21 and a second pad 32. The second groove 21 is formed on a first side of the second clamp 2 and extends through to the first end face of the second clamp 2 along the length direction of the high-strength metal sample. The second pad 32 is detachably assembled in the second groove 21. The second clamping surface 20 is the wall surface of the second pad 32 away from the second groove 21.

[0031] In this technical solution, the clamping structure is specifically formed by a groove formed on the side of the corresponding clamp and a pad that can be detachably assembled with the groove. As a component that directly clamps and contacts the metal sample, the pad can be replaced or replaced according to the actual situation, which can improve the structural versatility of this utility model, reduce the material requirements of the first clamp 1 and the second clamp 2, and reduce the maintenance cost of the clamp.

[0032] In some embodiments, the mechanical strength of the first pad 31 and the second pad 32 is higher than that of the first clamp 1 and the second clamp 2, which can improve the wear resistance of the first pad 31 and the second pad 32 and extend the service life of the clamp.

[0033] The first pad 31 and the first groove 11, and the second pad 32 and the second groove 21 are fixedly connected by a positioning structure (not indicated in the figure) to ensure that the first pad 31 and the second pad 32 maintain a relatively stable position during the tensile and torsional process of the metal sample, so as to ensure reliable operation of the metal sample.

[0034] The grooves of the first groove 11 and the second groove 21 at the first end face are rounded, that is, the edges of the grooves of the first groove 11 and the second groove 21 on the first end face are rounded. This can further prevent the fixture from contacting the metal sample and causing stress concentration, and reduce the probability of biting the sample.

[0035] In some embodiments, as specifically shown in FIG. 2, the positioning structure includes a limiting convex rib (not labeled in the figure) and a limiting groove (not labeled in the figure). Among them, the limiting convex rib is formed on the wall surface of the first cushion layer 31 facing the first groove 11 and on the wall surface of the second cushion layer 32 facing the second groove 21, and the limiting groove is on the groove wall surfaces of the first groove 11 and the second groove 21. The limiting convex rib is fitted into the limiting groove. Specifically, a small clearance fit is adopted between the limiting convex rib and the limiting groove, and the specific clearance size is such that it is convenient for the free disassembly and assembly of the limiting convex rib and the limiting groove while ensuring the positioning accuracy.

[0036] As specifically shown in FIG. 2, in a specific embodiment, the limiting convex rib includes an axial convex rib 301 and a circumferential convex rib 302 that intersect. The limiting groove includes an axial groove (not shown in the figure) that is fitted with the axial convex rib 301 and a circumferential groove (not shown in the figure) that is fitted with the circumferential convex rib 302. The aforementioned axial direction refers to the direction along which the specimen is stretched, that is, the length direction, and the circumferential direction refers to the direction around the outer circumference of the specimen.

[0037] In this technical solution, through the corresponding fitting of the axially arranged axial convex rib 301 and circumferential convex rib 302 with the axial groove and circumferential groove respectively, the axial and axial (rotational) fixation of both the first cushion layer 31 and the second cushion layer 32 can be achieved simultaneously, ensuring the reliable and stable fixation of one end position of the metal specimen.

[0038] In some embodiments, the first end face is the side end face of the first fixture 1 and the second fixture 2 close to the gauge section of the high-strength metal specimen (with reference to the orientation shown in FIG. 1, the gauge section is located above the first end face of the fixture). The thickness of the first cushion layer 31 and the second cushion layer 32 is h, and the fixture thickness of the first fixture 1 and the second fixture 2 corresponding to the first end face is H, where 0.1 mm < h < H. In this way, while ensuring that the first cushion layer 31 and the second cushion layer 32 have sufficient mechanical strength, it can be ensured that the first fixture 1 and the second fixture 2 form a reliable surrounding and wrapping of the first cushion layer 31 and the second cushion layer 32, preventing the first cushion layer 31 and the second cushion layer 32 from turning outwards at the position close to the gauge section.

[0039] The first end face is the side of the first clamp 1 and the second clamp 2 closest to the gauge length of the high-strength metal sample. The side of the first clamp 1 and the second clamp 2 opposite to the first end face is the second end face, that is, the side of the first clamp 1 and the second clamp 2 away from the gauge length. From the second end face to the first end face, the mechanical strength of the first pad 31 and the second pad 32 decreases, that is, from the second end face to the first end face, the strength of the first pad 31 and the second pad 32 forms a gradient, which can be a linear gradient or an integral gradient, etc. Specifically, the micro Vickers hardness of the first pad 31 and the second pad 32 at the corresponding positions of the second end face is Hv. H The micro Vickers hardness of the positions corresponding to the first end face is Hv. L The microVickers hardness of the clamping section of the high-strength metal sample is Hv. sample Hv H >Hv sample Hv L >0.3Hv sample The yield strengths of the first pad 31 and the second pad 32 at the positions corresponding to the second end face are σ. H The yield strengths at the positions corresponding to the first end face are σ. L The tensile strength of the high-strength metal specimen is σ. sample , σ H >σ sample , σ L >0.3σ sample .

[0040] In this technical solution, the mechanical strength of the first pad 31 and the second pad 32 decreases progressively from the second end face to the first end face. This prevents breakage near the clamping area caused by a sudden drop in clamping force or mechanical biting at the clamping edge, thus avoiding test failure. It is understood that the aforementioned gauge length is the free section of the sample, without clamping constraints. However, the tensile test requires the sample to break within the gauge length to be considered valid. Using a high-strength material away from the gauge length (i.e., near the aforementioned second end face) prevents slippage during clamping, and the area away from the gauge length is a surface contact coverage area, eliminating concerns about mechanical biting. A low-strength pad is used near the clamping position close to the gauge length (i.e., near the aforementioned first end face) to provide a transition in clamping strength from the clamping section to the free gauge length, preventing stress concentration caused by a sudden drop in clamping force and breakage near the clamping point. Furthermore, the low-strength clamp prevents the filament from breaking near the clamping point after mechanical biting.

[0041] In some embodiments, the thickness of the first clamp 1 and the second clamp 2 gradually decreases from the end away from the gauge length of the high-strength metal sample to the end near the gauge length, so that the side of the first clamp 1 and the second clamp 2 facing away from each other is an inclined surface. This makes the clamp in this invention a wedge-shaped structure. In this way, the wedge-shaped structure can be matched with the corresponding structure on the tensile testing machine or fatigue testing machine to ensure that the first clamp 1 and the second clamp 2 are reliably clamped.

[0042] The first clamp 1 and the second clamp 2 are respectively constructed with connection holes 4 for connecting to testing equipment (such as tensile testing machine or fatigue testing machine). A pin can be inserted into the connection hole 4 and connected to the testing equipment. When the lifting mechanism of the testing equipment descends, it can drive the first clamp 1 and the second clamp 2 to generate a certain displacement synchronously, thereby releasing the clamps of the first clamp 1 and the second clamp 2 from the metal sample.

[0043] In one specific embodiment, the high-strength metal sample is a wire with a diameter d ≥ 0.1 mm; the aforementioned first pad 31 and second pad 32 are made of a material with a high coefficient of friction (static friction coefficient μ > 0.7).

[0044] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0045] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model. The above description is only a preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. A surface contact fixture for tensile and torsional stress on high-strength metal specimens, characterized in that, The fixture includes a first clamp (1) and a second clamp (2). A first clamping structure is formed on a first side of the first clamp (1), and a second clamping structure is formed on a first side of the second clamp (2). The first clamping structure has a first clamping surface (10), and the second clamping structure has a second clamping surface (20). When the surface contact fixture is subjected to a tensile torsion test, the first clamping surface (10) and the second clamping surface (20) can form a surface contact surrounding the outer peripheral wall of the high-strength metal sample along the length direction of the high-strength metal sample.

2. The surface contact fixture according to claim 1, characterized in that, The first clamping structure is a first groove (11), which is formed on the first side of the first clamp (1) and extends through the first end face of the first clamp (1) along the length direction of the high-strength metal sample. The first clamping surface (10) is the groove wall surface of the first groove (11). The second clamping structure is a second groove (21), which is formed on the first side of the second clamp (2) and extends through the first end face of the second clamp (2) along the length direction of the high-strength metal sample. The second clamping surface (20) is the groove wall surface of the second groove (21).

3. The surface contact fixture according to claim 1, characterized in that, The first clamping structure includes a first groove (11) and a first pad (31). The first groove (11) is formed on the first side of the first clamp (1) and extends through the first end face of the first clamp (1) along the length direction of the high-strength metal sample. The first pad (31) is detachably assembled in the first groove (11). The first clamping surface (10) is the wall surface of the first pad (31) away from the first groove (11). The second clamping structure includes a second groove (21) and a second pad (32). The second groove (21) is formed on the first side of the second clamp (2) and extends through the first end face of the second clamp (2) along the length direction of the high-strength metal sample. The second pad (32) is detachably assembled in the second groove (21). The second clamping surface (20) is the wall surface of the second pad (32) away from the second groove (21).

4. The surface contact fixture according to claim 3, characterized in that, The mechanical strength of the first pad (31) and the second pad (32) is higher than that of the first clamp (1) and the second clamp (2); and / or, the first pad (31) and the first groove (11) and the second pad (32) and the second groove (21) are fixedly connected by a positioning structure; and / or, the grooves of the first groove (11) and the second groove (21) at the first end face are rounded.

5. The surface contact fixture according to claim 4, characterized in that, The positioning structure includes a limiting protrusion and a limiting groove. The limiting protrusion is formed on the wall surface of the first pad (31) facing the first groove (11) and the wall surface of the second pad (32) facing the second groove (21). The limiting groove is located on the groove wall surface of the first groove (11) and the second groove (21). The limiting protrusion is embedded in the limiting groove.

6. The surface contact fixture according to claim 5, characterized in that, The limiting protrusion includes an axial protrusion (301) and a circumferential protrusion (302) that form an intersection, and the limiting groove includes an axial groove that matches and is fitted with the axial protrusion (301) and a circumferential groove that matches and is fitted with the circumferential protrusion (302).

7. The surface contact fixture according to claim 3, characterized in that, The first end face is the side end face of the first clamp (1) and the second clamp (2) near the gauge length of the high-strength metal sample. The thickness of the first pad (31) and the second pad (32) is h, and the clamp thickness of the first clamp (1) and the second clamp (2) corresponding to the first end face is H, 0.1 mm. <h<H。 8. The surface contact fixture according to claim 3, characterized in that, The first end face is the side end face of the first clamp (1) and the second clamp (2) near the gauge length of the high-strength metal sample. The side end face of the first clamp (1) and the second clamp (2) opposite to the first end face is the second end face. In the direction from the second end face to the first end face, the mechanical strength of the first pad (31) and the second pad (32) decreases.

9. The surface contact fixture according to claim 8, characterized in that, The micro Vickers hardness of the first pad (31) and the second pad (32) at the positions corresponding to the second end face is Hv. H The micro Vickers hardness of the positions corresponding to the first end face is Hv. L The microVickers hardness of the clamping section of the high-strength metal sample is Hv. sample Hv H >Hv sample Hv L >0.3Hv sample The yield strengths of the first cushion layer (31) and the second cushion layer (32) at the positions corresponding to the second end face are σ. H The yield strengths at the positions corresponding to the first end face are σ. L The tensile strength of the high-strength metal specimen is σ. sample , σ H >σ sample , σ L >0.3σ sample .

10. The surface contact fixture according to claim 1, characterized in that, The thickness of the first clamp (1) and the second clamp (2) gradually decreases from one end away from the gauge length of the high-strength metal sample to the end near the gauge length, so that the side of the first clamp (1) and the second clamp (2) facing away from each other is a slope; and / or, the first clamp (1) and the second clamp (2) are respectively provided with connection holes (4) for connecting to the test equipment.

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