CN220708890U - Universal material testing machine with damping device - Google Patents

Abstract

The utility model discloses a universal material testing machine with a damping device, wherein a workbench is supported on a rack through the damping device, an upright post is arranged on the workbench, the top end of the upright post is connected with an upper cross beam, a movable cross beam is arranged between the workbench and the upper cross beam, the movable cross beam is driven by a test loading device, the damping device comprises a first hydraulic buffer, a workbench bracket and a supporting plate, the first hydraulic buffer is arranged on the supporting plate, the working end of the first hydraulic buffer is downward and is abutted with the upper side surface of the supporting plate, and the workbench is supported on the supporting plate; the hydraulic buffer device also comprises a second hydraulic buffer, a buffer plate and a hooking bolt, wherein the buffer plate is positioned at the lower part of the supporting plate; the second hydraulic buffer is arranged on the buffer plate, the working end of the second hydraulic buffer is upwards abutted with the lower side face of the supporting plate, and the workbench bracket, the supporting plate and the buffer plate are connected through hooking bolts. The hydraulic buffer is used for absorbing vibration energy generated when the material breaks, so that impact and vibration are reduced, noise is low, and the safety of a test is improved.

Description

Universal material testing machine with damping device

Technical Field

The utility model relates to a universal material testing machine, in particular to a universal material testing machine with a damping device, and belongs to the technical field of testing equipment.

Background

The universal material testing machine is mainly suitable for testing metal and nonmetal materials, and the items which can be tested are various tensile stress, tensile strength, compression test, bending test and the like. The most widely used are tensile and compressive tests. The limit test of breaking the pull force is often carried out when the pull test is carried out on the workpiece, when the limit of the workpiece is broken, the product can be pulled greatly between the upper jaw and the lower jaw, the pull force can be transmitted to the frame, and strong vibration and impact are generated on the frame, so that the service life and the test precision of the tester are affected.

In order to solve the above problems, the applicant proposes a corresponding solution, such as a universal material testing machine with damping mechanism disclosed in CN215768005U, comprising a frame, a workbench, a sample clamping device and a test loading device, wherein the workbench is supported on the frame by a spring device, and specifically, two ends of the workbench are connected with workbench brackets, and the spring device comprises a main bearing damping spring, an auxiliary damping spring and a connecting bolt. The workbench is provided with a stand column, the top end of the stand column is connected with an upper cross beam, a movable cross beam is arranged between the workbench and the upper cross beam, and the movable cross beam is driven by the test loading device; the test loading device comprises two hydraulic cylinders, the hydraulic cylinders are connected to the workbench along the vertical direction, the output ends of the hydraulic cylinders are connected with the movable cross beam, and a guide device is arranged between the upper cross beam and the movable cross beam; the sample clamping device comprises an upper jaw device arranged on the upper cross beam and a lower jaw device correspondingly arranged on the movable cross beam. The spring-type vibration-free device has the advantages that vibration energy generated when the spring absorbs the material is broken is absorbed, so that the device is free of vibration and impact when in use, low in noise is generated, and the service life of the device can be prolonged. However, the damping force of the spring is not adjustable by adopting the spring as a damping device, and fatigue fracture can be generated after the spring acts for a plurality of times exceeding the service life of the spring under the action of alternating load.

In the prior art, most of test machines use wedge-shaped clamping jaws, which generally consist of wedge-shaped clamping seats, hydraulic cylinders, jaw baffles, sliding blocks, power driving plates, clamping blocks and the like, wherein the structure is in a bilateral symmetry mode; the piston rod of the hydraulic cylinder penetrates out from the bottom of the U-shaped cavity and is connected with the power driving plate. The working process is that, taking the following jaw device as an example, during tensile test, the piston rod of the hydraulic cylinder rises to push the power driving plate to move upwards, the power driving plate pushes the clamping blocks and the sliding blocks to move upwards together, and because the clamping seat is wedge-shaped, the top opening is small, the two clamping blocks move upwards in the process of moving upwards, and also generate opposite horizontal movement to generate clamping effect, and along with the increase of test tensile force, the clamping force of the clamping blocks on the sample is also increased, so that the sample is automatically locked and cannot be pulled out. The test device has the advantages that after the test sample is clamped, the clamping force is increased along with the increase of the test load, and the test sample is not easy to slip. However, the defects are obvious, the wedge-shaped clamp is a passive clamp, the clamping effect of the wedge-shaped clamp is related to the states of the test force and the clamping block, when the test force is larger, the clamping force is larger, but when the test force suddenly disappears (namely, a sample breaks), the clamping force suddenly disappears, the clamp suddenly loosens, and the clamp is impacted and has serious vibration and sound due to the inertia action of the original force. In addition, when the upper jaw device and the lower jaw device clamp the sample, the clamping blocks are driven by the hydraulic cylinder to drive the power driving plate to move upwards together with the sliding block, and in the process of upwards moving the left clamping block and the right clamping block, opposite horizontal movement is generated simultaneously to clamp the sample, so that the upper jaw device and the lower jaw device can apply opposite compression force to the sample in the axial direction, the sample with smaller diameter is bent, and the sample of brittle materials can be damaged even.

Disclosure of Invention

The utility model aims to overcome the defects in the prior art and provides a universal material testing machine with a damping device so as to solve the problems in the background art.

In order to achieve the above purpose, the present utility model adopts the following technical scheme:

the utility model provides a universal material testing machine with damping device, includes frame, workstation, sample clamping device and test loading device, and the workstation passes through damping device and supports in the frame, is provided with the stand on the workstation, and the top of stand is connected with the entablature, sets up movable cross beam between workstation and the entablature, and movable cross beam is driven by test loading device, its characterized in that: the damping device comprises a first hydraulic buffer, workbench brackets arranged at two ends of the workbench and a supporting plate arranged on the rack and positioned at the lower part of the workbench brackets, wherein the mounting end of the first hydraulic buffer is connected to the supporting plate, the working end of the first hydraulic buffer is downward abutted with the upper side surface of the supporting plate, and the workbench is supported on the supporting plate; the hydraulic buffer device also comprises a second hydraulic buffer, a buffer plate and a hooking bolt, wherein the buffer plate is positioned at the lower part of the supporting plate; the installation end of the second hydraulic buffer is connected to the buffer plate, the working end of the second hydraulic buffer is upwards abutted to the lower side face of the supporting plate, and the second hydraulic buffer absorbs impact energy when the metal material breaks, so that the whole equipment does not vibrate. The workbench bracket, the supporting plate and the buffer plate are connected through hooking bolts.

By adopting the technical scheme, the hydraulic buffer is arranged between the frame and the workbench, the noise is smaller than that of the spring damping work, the adjustable hydraulic buffer can be adjusted according to different impact speeds and impact forces, the requirements of various working conditions or parameter changes can be met, and the adjustment is convenient; the hydraulic buffer acts stably, so that the damping effect can be effectively ensured, and under the same use condition, the required travel distance of the hydraulic buffer is less than more than half of the travel distance of the spring buffer; the hydraulic buffer is adopted to absorb vibration energy generated when the material breaks, so that the testing machine acts stably in the process of applying and removing test force to the sample in a stretching way, impact and vibration are reduced, noise is low, the safety of the test is improved, and the service life of the equipment can be prolonged; the workbench is connected with the rack in a separated mode, so that vibration can be effectively reduced, the precision of experimental data can be improved, and the vibration reducing mechanism is simple in structure and convenient to maintain.

In the universal material testing machine with the damping device, the sample clamping device comprises an upper jaw device arranged on the upper beam and a lower jaw device correspondingly arranged on the movable beam; the upper jaw device and the lower jaw device have the same structure and comprise a clamp seat, a left cylinder and a right cylinder are arranged on the clamp seat, the extending directions of a left piston rod and a right piston rod of the cylinders are parallel, the extending directions are opposite, the ends of the left piston rod and the right piston rod are connected with jaw plates for clamping a test piece, and a device for preventing the piston rod from rotating is arranged between the jaw plates and the clamp seat.

Through adopting above-mentioned technical scheme, sample clamping device adopts hydraulic pressure pushing clamp, is an active anchor clamps, and its clamping force is irrelevant with the test force, needs independent one set of hydraulic system to this clamping force is directly applied to the sample, can directly carry out continuous adjustment to hydraulic system pressure on the software as required through the proportion overflow valve, through the joint control of proportion overflow valve and software, the clamping force of anchor clamps can rise along with the rising of test force according to certain proportion in the test process, can avoid the great sample of brittleness, can damage the sample because of the clamping force is great. The clamping force of the sample for the non-brittle material can be adjusted to be quite large, which is equivalent to or even exceeds the force of the testing machine, and the clamping force always clamps the sample tightly in the whole testing process no matter how large the testing force is, and the force cannot disappear when the sample breaks. The structural characteristics of the flat-pushing clamp can also keep no relative sliding between the jaw and the clamp seat in the test process, can better fix a sample in the test process, can not generate axial force affecting the test in the tensile direction, basically eliminates the influence of the clamp system on the test result, and enables the result to be closer to a true value. The device for preventing the piston rod from rotating is arranged between the jaw plate and the clamp seat, so that the piston rod can be prevented from rotating, the coaxiality and the verticality of the jaw clamping are ensured, the clamping of a sample is facilitated, and the test precision is improved.

Further, a U-shaped groove is arranged in the middle of the clamp seat, the two oil cylinders are symmetrically arranged on two sides of the U-shaped groove, and the end parts of the left piston rod and the right piston rod move in opposite directions from the two sides of the U-shaped groove and extend into the U-shaped groove.

Furthermore, the U-shaped groove of the clamp seat is of a structure with an open front end and a closed rear end, and the longitudinal section of the U-shaped groove is concave and the cross section of the U-shaped groove is pi-shaped; the device for preventing the piston rod from rotating comprises an anti-rotation pin arranged on the jaw plate and a horizontal long hole arranged on the clamp seat and on the rear side wall of the U-shaped groove, wherein the anti-rotation pin is connected to the rear side surface of the jaw plate, the axis of the anti-rotation pin is perpendicular to the rear side surface, and the anti-rotation pin can slide in the horizontal long hole.

Through adopting above-mentioned technical scheme, the U-shaped groove of anchor clamps seat is the open, rear end confined structure in front end, can improve the rigidity of anchor clamps seat, makes the clamping face of jaw board keep parallelism easily, improves the clamping accuracy and the holding power of keeping silent.

In the universal material testing machine with the damping device, the distance between the lower end of the jaw plate and the bottom of the U-shaped groove can allow the working end of the sample clamp to pass through.

Through adopting above-mentioned technical scheme, the distance between the bottom of the lower extreme of jaw board to the U-shaped groove can hold the work end of sample anchor clamps and pass through, makes things convenient for the robot to drive sample anchor clamps to snatch the sample waste material after the test.

Advantageous effects

1. According to the universal material testing machine with the damping device, the hydraulic buffer is arranged between the frame and the workbench, and the hydraulic buffer is used for absorbing vibration energy generated when a material breaks, so that the testing machine is stable in the process of applying and removing test force to a sample in a stretching manner, impact and vibration are reduced, noise is low, the safety of a test is improved, and the service life of equipment is prolonged; the workbench is connected with the rack in a separated mode, so that vibration can be effectively reduced, the precision of experimental data can be improved, and the mechanism is simple in structure and convenient to maintain.

2. The device for preventing the piston rod from rotating is arranged between the jaw plate and the clamp seat, so that the piston rod can be prevented from rotating, the coaxiality and the verticality of the jaw clamping are ensured, the clamping of a sample is facilitated, and the test precision is improved.

3. The U-shaped groove of the clamp seat is of a structure with an open front end and a closed rear end, so that the rigidity of the clamp seat can be improved, the clamping faces of the jaw plates can be easily kept parallel, and the clamping precision and the clamping force of the jaws are improved. The distance between the lower end of the jaw plate and the bottom of the U-shaped groove can allow the working end of the sample clamp to pass through, so that the robot can conveniently drive the sample clamp to grasp the sample waste after the test.

Drawings

Fig. 1 and 2 are overall schematic diagrams of the present utility model.

Fig. 3 is a schematic side view of the present utility model.

Fig. 4 is an enlarged partial schematic view of the shock absorbing device of fig. 3.

Fig. 5 is a schematic cross-sectional view of a shock absorbing device according to the present utility model.

Fig. 6 is a schematic cross-sectional view A-A of fig. 4.

FIG. 7 is a schematic front view of a sample held on a sample holding device according to the present utility model.

FIG. 8 is a schematic rear view of a sample held on a sample holding device according to the present utility model.

Fig. 9 is a schematic cross-sectional view of a lower jaw apparatus of the present utility model.

Fig. 10 is a schematic view of the device for preventing the piston rod from rotating in the present utility model.

In the figure: the device comprises a limit ring 1, a loading oil cylinder 2, a frame 3, a movable cross beam 4, a lower jaw device 5, a vertical column 6, an upper jaw device 7, an upper cross beam 8, a guide sleeve 9, a guide pillar 10, a load sensor 11, a flange 12, a workbench 13, a workbench bracket 14, a connecting bolt 15, a first hydraulic buffer 16, a support plate 17, a second hydraulic buffer 18, a hooking bolt 19, a buffer plate 20, a horizontal threaded hole 21, a clamp seat 22, a U-shaped groove 221, a horizontal long hole 222, a left piston rod 23, a right piston rod 24, a 25 end cover 26, a jaw plate 27 and an anti-rotation pin 27.

Detailed Description

In order to clearly illustrate the technical features of the present solution, the present utility model will be further described below by way of non-limiting examples with reference to the accompanying drawings.

The front, rear, left and right directions of the present utility model are described in terms of the front, rear, left and right directions shown in the drawings. For convenience of explanation, only portions relevant to the embodiments of the present utility model are shown.

Referring to fig. 1 to 3, a universal material testing machine with a damping device comprises a frame 3, a workbench 13, a sample clamping device and a test loading device, wherein the workbench 13 is supported on the frame 3 through the damping device 15, a stand column 6 is arranged on the workbench 13, the top end of the stand column 6 is connected with an upper cross beam 8, a movable cross beam 4 is arranged between the workbench 13 and the upper cross beam 8, a test space is divided into an upper part and a lower part, the sample clamping device comprises an upper jaw device 7 arranged on the upper cross beam 8 and a lower jaw device 5 correspondingly arranged on the movable cross beam 4, so that the test space of the upper part becomes a tensile test space, the lower part is a compression test space, and the movable cross beam 4 is driven by the test loading device to perform a tensile test or a compression test; the test loading device comprises a left loading cylinder 2 and a right loading cylinder 2, and the two loading cylinders 2 can drive the movable cross beam 4 at the same time, so that the movable cross beam 4 can be lifted more stably; the loading cylinder 2 is connected to the lower bottom surface of the workbench 13 through a front flange on the loading cylinder 2, a rod end of a piston rod of the loading cylinder 2 is connected with a flange 12, the flange 12 is connected with one end of the load sensor 11, and the other end of the load sensor 11 is connected with the movable cross beam 4. In order to improve the test precision, a guide device is arranged between the upper beam 8 and the movable beam 4, and comprises two guide sleeves 9 arranged on the upper beam 8 and guide posts 10 correspondingly arranged on the movable beam 4, wherein the guide posts 10 can slide in the guide sleeves 9. The lower part of the frame 3 is provided with an anti-tilting limiting device at a position corresponding to the loading cylinder 2, in this embodiment, the anti-tilting limiting device is a limiting ring 1 fixedly connected to the frame 3, and the inner diameter of the limiting ring 1 is slightly larger than the outer diameter of the cylinder barrel of the loading cylinder 2.

Specifically, please refer to fig. 4 to 6, two ends of the workbench 13 are connected with a workbench bracket 14, the damping device comprises a first hydraulic buffer 16 and a supporting plate 17 arranged on the frame 3 and positioned at the lower part of the workbench bracket 14, the mounting end of the first hydraulic buffer 16 is connected to the supporting plate 17, the working end of the first hydraulic buffer is downward and is abutted with the upper side surface of the supporting plate 17, and the workbench 13 is supported on the supporting plate 17; the hydraulic buffer device further comprises a second hydraulic buffer 18, a buffer plate 20 and a hooking bolt 19, wherein the buffer plate 20 is positioned at the lower part of the supporting plate 17; the installation end of the second hydraulic buffer 18 is connected to the buffer plate 20, and the working end of the second hydraulic buffer 18 is upwards abutted with the lower side surface of the supporting plate 17; the workbench bracket 14, the supporting plate 17 and the buffer plate 20 are respectively provided with vertical through holes which correspond up and down, wherein the vertical through holes on the buffer plate 20 are threaded holes, the threaded ends of the hooking bolts 19 sequentially penetrate through the vertical through holes on the workbench bracket 14 and the supporting plate 17 from top to bottom and then are screwed into the threaded holes on the buffer plate 20, and the hooking bolts 19 can slide in the vertical through holes on the workbench bracket 14 and the supporting plate 17. The side of the buffer plate 20 is provided with a horizontal screw hole 21 communicated with the screw hole, and a set screw is screwed into the horizontal screw hole 21 to prevent the hooking bolt 19 from loosening.

The first hydraulic buffer 16, the second hydraulic buffer 18 are connected with the supporting plate 17 and the buffer plate 20 in a concrete way, vertical threaded through holes are formed in the supporting plate 17 and the buffer plate 20, the first hydraulic buffer 16 and the second hydraulic buffer 18 are adjustable hydraulic buffers, the buffers are provided with external threaded cylinder bodies, the external threaded cylinder bodies of the buffers are screwed into the threaded through holes, and the screwing length is adjustable so as to adjust initial stress of the first hydraulic buffer 16 and the second hydraulic buffer 18.

Referring to fig. 7 to 10, the sample clamping device includes an upper jaw device 7 mounted on an upper beam 8 and a lower jaw device 5 correspondingly mounted on a movable beam 4; the upper jaw device 7 and the lower jaw device 5 have the same structure and respectively comprise a clamp seat 22, the clamp seats 22 can be respectively fixed on the upper beam 8 and the movable beam 4 in a welding mode, but in order to ensure that the installation and the maintenance are more convenient, the flexibility of use is higher, the clamp seats 22 are respectively detachably connected with the upper beam 8 and the movable beam 4 in the embodiment, for example, the clamp seats 22 are connected in a bolt connection mode, bolt holes are formed in the clamp seats 22, and the upper jaw device 7 and the lower jaw device 5 are respectively connected on the upper beam and the movable beam of the tester through bolts. The two ends of the sample are respectively clamped on the upper jaw device 7 and the lower jaw device 5, and the testing machine drives the movable cross beam to carry out tensile test on the sample.

Only the lower jaw apparatus 5 will be specifically described below. The clamp seat 22 is provided with a left cylinder and a right cylinder, in this embodiment, a U-shaped groove 221 is arranged in the middle of the clamp seat 22, the two cylinders are symmetrically arranged on two sides of the U-shaped groove 221, a cylinder body of each cylinder and the clamp seat 22 are of an integrated structure, specifically, two sides of the U-shaped groove on the clamp seat 22 are respectively provided with a cylinder head hole, the outer side of each cylinder head hole is provided with a piston hole, the outer end of each piston hole is sealed by an end cover 25, a piston is positioned in each piston hole and connected with the left piston rod 4/right piston rod 5, the piston and the left piston rod 4/right piston rod 5 can also be an integrated piston assembly, the piston divides the piston holes into a rod cavity and a rodless cavity, the clamp seat 22 is provided with a rod cavity oil port and a rodless cavity oil port (not shown in the figure) which are respectively communicated with the rod cavity and the rodless cavity, the end parts of the left piston rod 23 and the right piston rod 24 are respectively extended into the U-shaped groove 221 from the cylinder head holes on two sides of the U-shaped groove 221 in opposite directions, the extending directions of the left piston rod 23 and the right piston rod 24 are parallel, the extending directions of the piston rod 24 are opposite, the piston rod is also provided with a jaw plate 26, and a jaw plate 26 is arranged between the piston rod plate and the clamp seat 22.

The U-shaped groove of the clamp seat 22 has a structure with an open front end and a closed rear end, and the longitudinal section is concave and the cross section is pi-shaped; the device for preventing the piston rod from rotating comprises an anti-rotating pin 27 arranged on the jaw plate 26 and a horizontal long hole 222 arranged on the clamp seat 22 and on the rear side wall of the U-shaped groove 221, wherein the anti-rotating pin 27 is connected to the rear side surface of the jaw plate 26, the axis of the anti-rotating pin is vertical to the rear side surface, and the anti-rotating pin 27 can slide in the horizontal long hole 222.

The distance between the lower end of the jaw plate 26 and the bottom of the U-shaped channel 221 allows the working end of the sample clamp to pass.

The working principle of the embodiment is as follows:

in an actual tensile test, a robot drives a sample clamp to grasp a sample, then two ends of the sample are respectively placed into an upper jaw device and a lower jaw device, a left piston rod and a right piston rod of an upper oil cylinder of a clamp seat simultaneously extend out and move in opposite directions, and jaw plates at the ends of the left piston rod and the right piston rod are mutually close to clamp the sample; then starting the pressure testing machine, synchronously driving the movable cross beam 4 to move downwards with the lower jaw device by the two loading oil cylinders 2, and moving the lower end of the sample in a direction away from the upper end, so as to finally realize the stretching of the sample to be tested; when the test piece is broken, the upper jaw device 7 receives upward reaction force, and the reaction force is transmitted to the second hydraulic buffer 18 through the upper cross beam, the upright post, the workbench bracket, the hooking bolt and the buffer plate, and the second hydraulic buffer 18 is pressed to absorb upward impact force generated by the workbench; the first hydraulic buffer 16 is used for counteracting the resilience force generated by the second hydraulic buffer 18 during recovery, so that the whole machine reaches an energy system with mutually counteracted forces, and the test is free from vibration and impact, and effectively absorbs vibration energy generated by breaking the test sample. The lower jaw device 5 is subjected to downward reaction force, and the downward reaction force is transmitted to the first hydraulic buffer 16 through the movable cross beam 4, the load sensor 11, the flange 12, the piston rod of the loading cylinder 2, the hydraulic oil in the loading cylinder 2, the cylinder body of the loading cylinder 2, the workbench and the workbench bracket, but the downward reaction force is smaller than the upward reaction force applied by the second hydraulic buffer 18 due to the buffer of the hydraulic oil in the loading cylinder 2.

In describing the present utility model, it should be noted that the terms "left", "right", "front", "rear", "upper", "lower", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and the above-mentioned terms are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the apparatus or elements to be referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

Unless specifically stated or limited otherwise, the terms "mounted," "connected," and "coupled" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

Other than the technical features described in the specification, all are known to those skilled in the art.

The above-mentioned embodiments are only for understanding the present utility model, and are not intended to limit the technical solutions described in the present utility model, and a person skilled in the relevant art may make various changes or modifications based on the technical solutions described in the claims, and all equivalent changes or modifications are intended to be included in the scope of the claims of the present utility model.

Claims (5)

1. The utility model provides a universal material testing machine with damping device, includes frame, workstation, sample clamping device and test loading device, and the workstation passes through damping device and supports in the frame, is provided with the stand on the workstation, and the top of stand is connected with the entablature, sets up movable cross beam between workstation and the entablature, and movable cross beam is driven by test loading device, its characterized in that: the damping device comprises a first hydraulic buffer, workbench brackets arranged at two ends of the workbench and a supporting plate arranged on the rack and positioned at the lower part of the workbench brackets, wherein the mounting end of the first hydraulic buffer is connected to the supporting plate, the working end of the first hydraulic buffer is downward abutted with the upper side surface of the supporting plate, and the workbench is supported on the supporting plate; the hydraulic buffer device also comprises a second hydraulic buffer, a buffer plate and a hooking bolt, wherein the buffer plate is positioned at the lower part of the supporting plate; the installation end of the second hydraulic buffer is connected to the buffer plate, and the working end of the second hydraulic buffer is upwards and is abutted with the lower side surface of the supporting plate; the workbench bracket, the supporting plate and the buffer plate are connected through hooking bolts.

2. The universal material testing machine with shock absorbing device according to claim 1, wherein: the sample clamping device comprises an upper jaw device arranged on the upper cross beam and a lower jaw device correspondingly arranged on the movable cross beam; the upper jaw device and the lower jaw device have the same structure and comprise a clamp seat, a left cylinder and a right cylinder are arranged on the clamp seat, the extending directions of a left piston rod and a right piston rod of the cylinders are parallel, the extending directions are opposite, the ends of the left piston rod and the right piston rod are connected with jaw plates for clamping a test piece, and a device for preventing the piston rod from rotating is arranged between the jaw plates and the clamp seat.

3. The universal material testing machine with shock absorbing device according to claim 2, wherein: the fixture seat in the middle of be equipped with the U-shaped groove, two hydro-cylinders bilateral symmetry set up in the both sides of U-shaped groove, the tip of left piston rod and right piston rod is followed the both sides opposite movement of U-shaped groove respectively and is stretched into the U-shaped inslot.

4. A universal material testing machine with shock absorbing device as defined in claim 3, wherein: the U-shaped groove of the clamp seat is of a structure with an open front end and a closed rear end, and the longitudinal section of the U-shaped groove is concave and the cross section of the U-shaped groove is pi-shaped; the device for preventing the piston rod from rotating comprises an anti-rotation pin arranged on the jaw plate and a horizontal long hole arranged on the clamp seat and on the rear side wall of the U-shaped groove, wherein the anti-rotation pin is connected to the rear side surface of the jaw plate, the axis of the anti-rotation pin is perpendicular to the rear side surface, and the anti-rotation pin can slide in the horizontal long hole.

5. The universal material testing machine with shock absorbing device according to claim 3 or 4, wherein: the distance between the lower end of the jaw plate and the bottom of the U-shaped groove can allow the working end of the sample clamp to pass through.