CN217084451U

CN217084451U - Pipe test piece fatigue test anchor clamps

Info

Publication number: CN217084451U
Application number: CN202220785161.6U
Authority: CN
Inventors: 黄淼; 冯道臣; 李正阳; 李乘安; 周浩; 王文军; 郑文健
Original assignee: Zhejiang University of Technology ZJUT
Current assignee: Zhejiang University of Technology ZJUT
Priority date: 2022-04-07
Filing date: 2022-04-07
Publication date: 2022-07-29
Anticipated expiration: 2032-04-07

Abstract

The utility model relates to a pipe test piece fatigue test anchor clamps belongs to material fatigue performance detection technical field, and it includes the anchor clamps body that interval and symmetry set up about two, the anchor clamps body includes link and exposed core, the exposed core includes the anchor clamps seat at least, the anchor clamps seat is formed with inner opening and is the annular centre gripping space of circle, the axis in centre gripping space and the axis coincidence of link, inner circle one side in centre gripping space is equipped with a plurality of interior supporting parts that are used for with test piece inner circle butt, outer lane one side in centre gripping space is equipped with a plurality of outer supporting parts that are used for with test piece outer lane butt, and is a plurality of interior supporting part all uses the axis in centre gripping space to be circular array and distributes as the center with outer supporting part. The utility model discloses the axis that can make clamping back test piece can coincide with the axis in centre gripping space to can effectively guarantee the axiality of test piece and link, can guarantee the accuracy that test piece fatigue performance detected from this.

Description

Pipe test piece fatigue test anchor clamps

Technical Field

The utility model relates to a pipe test piece fatigue test anchor clamps belongs to material fatigue performance detection technical field.

Background

The fatigue testing machine is a common device and is widely used for detecting the fatigue performance of materials. The fatigue performance is a basic attribute of the material and is a detection means which is widely applied in the material performance detection. When in detection, the test piece is connected with the output end of the fatigue testing machine through the test fixture, the fatigue testing machine is utilized to apply axial force to the test piece so as to carry out tensile/compressive fatigue test, and the fatigue performance of the test piece is detected according to the test result.

The prior Chinese patent No. 201510232959.2, named as a high-temperature tension-compression fatigue test fixture for a hollow round bar test piece, comprises a joint, a connecting rod, a sleeve, a test piece cover, a hollow round bar test piece, a countersunk head bolt and a cooler joint; the optical rod end of the joint is connected with the fatigue machine, and the other end of the joint is connected with the thick end of the connecting rod through six countersunk head bolts; the hollow rod part of the connecting rod is sleeved in the sleeve, and the connecting rod is in threaded connection with the sleeve through a nut; the hollow round bar test piece is in threaded connection with the test piece cover; the test piece cover is in threaded connection with the sleeve; the end part of the hollow round bar test piece is propped by the hollow rod of the connecting rod; the cooler joint penetrates through the hole of the sleeve and is in threaded connection with the hollow part of the connecting rod; the device has the advantages that the device can meet the requirements of tensile/compression fatigue tests of the hollow round bar test piece under the temperature gradient, can stably clamp the hollow round bar test piece, and can perform the fatigue tests of the cooling air channel. It also has the following disadvantages: the test piece passes through the screw-thread fit and installs on test fixture for the test piece is difficult to guarantee with the axiality that connects, leads to the easy off-axis condition of appearing of test piece, in case the off-axis test piece appears then can receive partial radial force in the testing process, consequently is difficult to guarantee the accuracy scheduling problem that test piece fatigue performance detected.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a pipe test piece fatigue test anchor clamps, the test piece that has solved existence among the prior art is difficult to guarantee with the axiality of joint when installing on test anchor clamps, leads to the condition of off-axis to appear in the test piece easily, in case the off-axis test piece appears then can receive partial radial force in the testing process, consequently is difficult to guarantee the accuracy scheduling problem that test piece fatigue performance detected.

The above technical purpose of the present invention is mainly solved by the following technical solutions: a circular tube test piece fatigue test fixture, which comprises two fixture bodies which are arranged symmetrically and are spaced from each other left and right, the clamp body comprises a connecting end which is formed at the outer end of the clamp body and is used for clamping the clamp on the testing machine and a clamping end which is formed at the inner end of the clamp body and is used for clamping the end part of the test piece, the clamping end at least comprises a clamp seat, the clamp seat is provided with a clamping space which is provided with an opening at the inner end and is in a ring shape, the axis of the clamping space is superposed with the axis of the connecting end, the inner diameter of the clamping space is smaller than the inner diameter of the test piece, the outer diameter of the clamping space is larger than that of the test piece, one side of the inner ring of the clamping space is provided with a plurality of inner clamping parts which are used for abutting against the inner ring of the test piece, the outer lane one side in centre gripping space is equipped with a plurality of outer clamping parts that are used for with test piece outer lane butt, and is a plurality of interior clamping part and outer clamping part all use the axis in centre gripping space to be circular array distribution as the center.

When the device is used, an operator firstly inserts two end parts of a test piece into the clamping space in two clamp bodies correspondingly, and the pipe wall of the test piece is positioned between an inner clamping part and an outer clamping part, then the inner clamping part and the outer clamping part are respectively matched with the inner ring and the outer ring of the test piece in a butting way, thereby realizing the stable clamping of the test piece, then the connecting end in the clamp body is connected with the output end of a fatigue testing machine, axial force is exerted on the test piece through the fatigue testing machine to carry out tensile/compression fatigue testing, the fatigue performance of the test piece is detected according to the test result, wherein the inner clamping parts and the outer clamping part can be abutted with a plurality of positions in the circumferential direction of the test piece at equal intervals during the clamping, so that the circumferential direction of the test piece can be stressed evenly, thereby the axial line of the test piece after the clamping can be coincided with the axial line of the clamping space, thereby the coaxiality of the test piece and the connecting end can be effectively ensured, thereby can prevent effectively that the condition of off-axis from appearing in the test piece to can guarantee that the test piece only receives axial force in the testing process, can guarantee the accuracy that test piece fatigue performance detected from this, two other anchor clamps specifically adopt the design of disconnect-type, can be applicable to the test piece of different length, and can be applicable to the test piece of different inside and outside footpath sizes, the scope of being applicable mainly depends on the inside and outside footpath size in centre gripping space.

Preferably, the inner clamping portion includes at least an inner collet, the inner collet is indirectly or directly slidably supported at one side of an inner ring of the clamping space, the inner collet is movable inward or outward in a radial direction of the clamping space, the outer clamping portion includes at least an outer collet, the outer collet is indirectly or directly slidably supported at one side of an outer ring of the clamping space, and the outer collet is movable inward or outward in the radial direction of the clamping space.

The inner chuck is arranged in the inner clamping part, the inner chuck is indirectly or directly supported on one side of the inner ring of the clamping space in a sliding manner, the inner chuck can move inwards or outwards along the radial direction of the clamping space, the outer chuck is arranged in the outer clamping part, the outer chuck is indirectly or directly supported on one side of the outer ring of the clamping space in a sliding manner, the outer chuck can move inwards or outwards along the radial direction of the clamping space, so that the inner chuck and the outer chuck can be respectively abutted against the inner ring and the outer ring of the test piece by controlling the inner chuck to move outwards along the radial direction of the clamping space and controlling the outer chuck to move inwards along the radial direction of the clamping space during clamping, the stable clamping of the test piece can be realized by matching the inner chuck and the outer chuck, the test piece can be loosened by controlling the inner chuck and the outer chuck to move towards opposite directions during disassembling, and the automatic centering of the test piece can be realized by controlling the inner chuck and the outer chuck to move towards the same distance, thereby make the axis of test piece after the clamping can coincide with the axis in centre gripping space to can guarantee the axiality of test piece and link.

Preferably, the plurality of inner clamping parts correspond to the plurality of outer clamping parts one by one, and the inner chucks in the inner clamping parts and the outer chucks in the outer clamping parts corresponding to the inner chucks move along the same radial line of the clamping space.

Through setting up a plurality of interior supporting parts into with a plurality of outer supporting parts one-to-one, interior chuck in the interior supporting part and the outer chuck in the outer supporting part that corresponds with it move along same radial line in centre gripping space, make each interior chuck can align to the point of application of force of test piece inner circle with each outer chuck point of application of force to the test piece outer lane, make the stress position of test piece inner and outer lane concentrate in the both sides that the pipe wall is relative, can strengthen the clamping effect to the test piece, in order to improve the stability that detects, and the effect of test piece self-centering after the clamping is better, more can guarantee the axiality of test piece and link.

As preferred, still be equipped with the interior application of force space and the outer application of force space that are located the radial inboard in centre gripping space and the outside respectively in the anchor clamps seat, centre gripping space, interior application of force space and outer application of force space all are the coincidence of the axis of ring form and three, be formed with the annular interior support piece of circle between centre gripping space and the interior application of force space, interior clamping part still includes the interior fixed cover of wearing to establish on interior support piece along the radial fixation in centre gripping space, interior chuck supports on interior support piece through interior fixed cover sliding, be formed with the annular outer support piece of circle between centre gripping space and the outer application of force space, outer clamping part still includes the outer fixed cover of wearing to establish on outer support piece along the radial fixation in centre gripping space, outer chuck supports on outer support piece through outer fixed cover sliding.

The inner force application space and the outer force application space which are respectively positioned on the radial inner side and the radial outer side of the clamping space are also arranged in the clamp seat, the clamping space, the inner force application space and the outer force application space are all in a circular ring shape, the axes of the clamping space, the inner force application space and the outer force application space are overlapped, a circular ring-shaped inner supporting piece is formed between the clamping space and the inner force application space, the inner clamping part also comprises an inner fixing sleeve fixedly arranged on the inner supporting piece in a penetrating way along the radial direction of the clamping space, the inner clamping head is slidably supported on the inner supporting piece through the inner fixing sleeve, a circular ring-shaped outer supporting piece is formed between the clamping space and the outer force application space, the outer clamping part also comprises an outer fixing sleeve fixedly arranged on the outer supporting piece in a penetrating way along the radial direction of the clamping space, and the outer clamping head is slidably supported on the outer supporting piece through the outer fixing sleeve, so that the inner clamping head and the outer clamping head can play a role in guiding way along the radial direction of the clamping space, the moving precision of the inner chuck and the outer chuck can be guaranteed, so that the clamping and centering effects are guaranteed, and in addition, the inner chuck and the outer chuck can be respectively installed on the inner supporting piece and the outer supporting piece through the inner fixing sleeve and the outer fixing sleeve, so that the clamping of a plurality of circumferential positions of the inner ring and the outer ring of the test piece is realized.

Preferably, the inner fixing sleeve is formed with a first guide groove extending in a radial direction of the clamping space and having an outer end opened, the inner clamping head is arranged in the first guide groove in a sliding mode, the outer end of the inner clamping head extends out of the outer end opening of the first guide groove into the clamping space, a first compression spring is sleeved in the first guide groove, the inner end of the first compression spring is abutted against the groove bottom of the first guide groove, the outer end of the first compression spring is abutted with the inner end of the inner chuck, the outer fixing sleeve is provided with a second guide groove which extends along the radial direction of the clamping space and is provided with an opening at the inner end, the outer chuck is arranged in the second guide groove in a sliding mode, the inner end of the outer chuck extends out of the inner end opening of the second guide groove to the clamping space, the second guide way endotheca is equipped with second compression spring, the tank bottom butt of second compression spring outer end and second guide way, the outer end butt of the inner and outer chuck of second compression spring.

When a first guide groove which radially extends along the clamping space and is provided with an opening at the outer end is formed in the inner fixed sleeve, the inner chuck is arranged in the first guide groove in a sliding manner, the outer end of the inner chuck extends into the clamping space from the opening at the outer end of the first guide groove, a first compression spring is sleeved in the first guide groove, the inner end of the first compression spring is abutted against the groove bottom of the first guide groove, the outer end of the first compression spring is abutted against the inner end of the inner chuck, a second guide groove which radially extends along the clamping space and is provided with an opening at the inner end is formed in the outer fixed sleeve, the outer chuck is slidably arranged in the second guide groove, the inner end of the outer chuck extends into the clamping space from the opening at the inner end of the second guide groove, a second compression spring is sleeved in the second guide groove, the outer end of the second compression spring is abutted against the groove bottom of the second guide groove, the inner end of the second compression spring is abutted against the outer end of the outer chuck, so that the end of the test piece is inserted into the clamping space and the pipe wall of the test piece is positioned between the inner chuck and the outer chuck, because the thickness of test piece pipe wall can make interior chuck and outer chuck move to the one side of keeping away from the test piece surface respectively, first compression spring and second compression spring are held power by the compression simultaneously, can exert certain pretightning force to the test piece from this to reach a fixed effect in advance, thereby can carry out rough fixed to the clamping position of test piece, and can finely adjust the centre gripping angle and the distance of test piece, so that can accurately centre gripping the appointed clamping position of test piece during follow-up clamping.

Preferably, the outer end of the inner chuck is hemispherical, the inner end of the outer chuck is in an arc shape matched with the outer ring of the test piece, and the outer end of the inner chuck is elastically abutted to the inner end of the outer chuck in an initial state.

The outer end of the inner chuck is hemispherical, the inner end of the outer chuck is in an arc shape matched with the outer ring of the test piece, the outer end of the inner chuck is elastically abutted to the inner end of the outer chuck in an initial state, the pipe wall of the test piece is inserted into the inner chuck and the outer chuck, the inner chuck can be automatically moved to one side far away from the surface of the test piece, the pipe wall of the test piece is smoothly inserted into the inner chuck and the outer chuck, the first compression spring and the second compression spring can be enabled to have larger compression distance, enough pre-tightening force can be applied, the pre-fixing effect can be guaranteed, the inner chuck can be reduced, and the damage to the surface of the test piece caused by the outer chuck when the outer chuck is abutted to the surface of the test piece can be reduced.

As preferred, the outer clamping part outside is equipped with the electromagnetic component that is used for producing magnetic field in the region at outer chuck place, the electromagnetic component includes that many lay the internal wire of outer application of force space outer lane wall, many the circumference in outer application of force space is followed to the wire and is extended the round, many the axial equidistance interval in outer application of force space is followed to the wire sets up, many the wire is integrated to cable joint and is linked to each other with external power source, outer chuck has magnetism and radially inwards or outwards removes in order to follow clamping space under the effect of electromagnetic force.

The outer clamping part is provided with an electromagnetic assembly used for generating a magnetic field in an area where the outer clamping head is located, the electromagnetic assembly comprises a plurality of wires laid in an outer ring wall body of the outer force application space, the plurality of wires extend for a circle along the circumferential direction of the outer force application space, the plurality of wires are arranged at equal intervals along the axial direction of the outer force application space, the plurality of wires are integrated into a cable connector and connected with an external power supply, the outer clamping head has magnetism so as to move inwards or outwards along the radial direction of the clamping space under the action of electromagnetic force, current on the wires can generate the magnetic field in the area where the outer clamping head is located after the external power supply is started, the outer clamping head can move inwards along the radial direction of the clamping space under the action of the electromagnetic force, so that the outer clamping head can be matched with the inner clamping head to apply clamping force on a test piece, stable clamping on the test piece is realized, and the outer clamping head can be controlled to move inwards or outwards along the radial direction of the clamping space by controlling the direction of the current, so as to realize the clamping and the dismantlement of test piece to the direction that changes the electric current during dismantlement can make outer chuck along the radial outside removal in centre gripping space, is convenient for take out the test piece, makes the clamping of test piece dismantle conveniently, and the size of alright ration adjustment clamping-force still can be passed through the size of adjustment electric current in addition.

Preferably, the first guide groove and the second guide groove each include a small diameter portion located on one side of an opening of the first guide groove and a large diameter portion located on the other side of the opening of the first guide groove, an annular end surface is formed at a joint of the small diameter portion and the large diameter portion, a limiting protrusion in sliding fit with the corresponding large diameter portion is respectively formed by extending the inner end of the inner chuck and the outer end of the outer chuck towards the respective radial outer side, and the inner chuck and the outer chuck are respectively in sliding fit with the corresponding small diameter portion.

Through all being equipped with the major diameter portion that is located its opening one side and the opposite side at first guide way and second guide way, the linking department of minor diameter portion and major diameter portion is formed with annular end face, interior chuck inner and outer chuck outer end extend respectively towards radial outside separately and be formed with the spacing arch with the major diameter portion sliding fit who corresponds, interior chuck and outer chuck are sliding fit with the minor diameter portion that corresponds respectively, make interior chuck and outer chuck can slide along first guide way and second guide way respectively, can guarantee the removal precision of interior chuck and outer chuck, can guarantee the accuracy of application of force direction, can realize the limiting displacement to interior chuck and outer chuck through the cooperation between annular end face and the spacing arch simultaneously, can avoid the chuck to pop out from the fixed cover.

Preferably, the inner clamping part and the outer clamping part are arranged in a plurality of circles at equal intervals along the axial direction of the clamping space, and the outer end of the clamping space is closed and is formed with a plane.

Through with interior clamping part and outer clamping part along the axial equidistance interval in centre gripping space be equipped with many rings, the outer end in centre gripping space seals and is formed with the plane, can greatly increased the grip area to the test piece, thereby strengthen the clamping effect to the test piece, and can make the tip of test piece and the outer end contact in centre gripping space during the clamping, with this can guarantee that two tip of test piece insert the degree of depth unanimity in the centre gripping space, make the distance of centre gripping unanimous, the lifting surface area is the same, can further guarantee the accuracy that test piece fatigue performance detected.

Preferably, the connecting end and the clamping end are fixedly connected in a detachable mode.

Through setting up link and exposed core into with detachable mode fixed connection for the link can be changed, with the fatigue testing machine who is applicable to different models.

Therefore, the utility model discloses can realize the even atress of test piece circumference to make the axis of test piece can coincide with the axis in centre gripping space behind the clamping, thereby can effectively guarantee the axiality of test piece and link, thereby can effectively prevent that the condition of off-axis from appearing in the test piece, thereby can guarantee that the test piece only receives the axial force in the testing process, can guarantee the accuracy that test piece fatigue performance detected from this.

Drawings

Fig. 1 is a schematic perspective view of the present invention;

FIG. 2 is a schematic perspective view of the clamp body of the present invention;

FIG. 3 is a schematic side view of the clamp body according to the present invention;

fig. 4 is a schematic view of the sectional structure of the inner clamping part and the outer clamping part of the present invention.

The scores in the figures are as follows: 1. a clamp body; 2. a connecting end; 3. a clamping end; 4. a clamp seat; 5. a clamping space; 6. an inner clamping part; 7. an outer clamping part; 8. an inner chuck; 9. an outer collet; 10. an inner force application space; 11. an outer force application space; 12. an inner support; 13. an inner fixing sleeve; 14. an outer support; 15. an outer fixing sleeve; 16. a first guide groove; 17. a first compression spring; 18. a second guide groove; 19. a second compression spring; 20. an electromagnetic assembly; 21. a wire; 22. a cable joint; 23. an annular end face; 24. and a limiting bulge.

Detailed Description

The technical solution of the present invention is further specifically described below by way of examples and with reference to the accompanying drawings.

As shown in figures 1, 2 and 3, the round tube test piece fatigue test fixture of the utility model comprises two fixture bodies 1 which are symmetrically arranged at left and right intervals, wherein each fixture body 1 comprises a connecting end 2 which is formed at the outer end of the fixture body and is used for clamping the fixture on the testing machine and a clamping end 3 which is formed at the inner end of the fixture body and is used for clamping the end part of the test piece, the connecting end 2 and the clamping end 3 are both cylindrical, the axes of the connecting end 2 and the clamping end 3 are coincided, the connecting end 2 and the clamping end 3 are fixedly connected in a detachable mode, the end part of the connecting end 2 connected with the clamping end 3 is provided with a mounting flange and is connected through a screw, the clamping end 3 at least comprises a fixture seat 4, the fixture seat 4 is cylindrical, the axis of the fixture seat 4 is coincided with the axis of the connecting end 2, the fixture seat 4 is provided with an inner end opening and is in a circular ring shape, the axis of the fixture seat 5 is coincided with the axis of the connecting end 2, the inner diameter of the fixture seat 5 is smaller than the inner diameter of the test piece, the outer diameter of the clamping space 5 is larger than that of the test piece, one side of the inner ring of the clamping space 5 is provided with a plurality of inner clamping parts 6 used for being abutted against the inner ring of the test piece, each inner clamping part 6 at least comprises an inner clamping head 8, the circumferential surface of each inner clamping head 8 is a cylindrical surface, the axis of each inner clamping head is radially overlapped with the clamping space 5, the outer end of each inner clamping head 8 is hemispherical, the outer end of each inner clamping head 8 can be spherical or circular truncated cone-shaped, each inner clamping head 8 is indirectly or directly supported on one side of the inner ring of the clamping space 5 in a sliding manner, each inner clamping head 8 can move inwards or outwards along the radial direction of the clamping space 5, one side of the outer ring of the clamping space 5 is provided with a plurality of outer clamping parts 7 used for being abutted against the outer ring of the test piece, each outer clamping part 7 at least comprises an outer clamping head 9, the circumferential surface of each outer clamping head 9 is a cylindrical surface, the axis of each outer clamping head 9 is radially overlapped with the clamping space 5, the inner end of each outer clamping head 9 is in an arc shape matched with the outer ring of the test piece, the outer chuck 9 is directly or indirectly slidably supported on the outer ring side of the clamping space 5, and the outer chuck 9 can move inward or outward in the radial direction of the clamping space 5.

As shown in fig. 2 and 3, the number of the inner clamping portions 6 and the number of the outer clamping portions 7 are six, the plurality of inner clamping portions 6 and the plurality of outer clamping portions 7 are distributed in a circular array with the axis of the clamping space 5 as the center, the inner clamping portions 6 and the plurality of outer clamping portions 7 are arranged in five circles along the axial direction of the clamping space 5 at equal intervals, the number of the circles can be more than five or less than five, depending on the length of the test piece, the outer end of the clamping space 5 is closed and is provided with a plane, the plurality of inner clamping portions 6 correspond to the plurality of outer clamping portions 7 one by one, the inner clamping head 8 in the inner clamping portion 6 and the outer clamping head 9 in the outer clamping portion 7 corresponding to the inner clamping portion move along the same radial line of the clamping space 5, and the inner clamping head 8 in the inner clamping portion 6 and the axis of the outer clamping head 9 in the outer clamping portion 7 corresponding to the inner clamping portion 6 coincide.

As shown in fig. 2 and 3, an inner force application space 10 and an outer force application space 11 are further provided in the fixture seat 4, the inner force application space 10 and the outer force application space 11 are respectively located on the radial inner side and the radial outer side of the clamping space 5, the inner force application space 10 and the outer force application space 11 are all circular and the axes of the three coincide, openings are formed at the inner ends of the inner force application space 10 and the outer force application space 11, the axial lengths of the clamping space 5, the inner force application space 10 and the outer force application space 11 are consistent, a circular inner support 12 is formed between the clamping space 5 and the inner force application space 10, the inner clamping part 6 further comprises an inner fixing sleeve 13 fixedly arranged on the inner support 12 along the radial direction of the clamping space 5, the inner clamping head 8 is slidably supported on the inner support 12 through the inner fixing sleeve 13, the inner end of the inner fixing sleeve 13 is abutted against the inner ring of the inner force application space 10, the inner end of the inner fixing sleeve 13 is configured to be an arc shape matched with the inner ring of the inner force application space 10, an annular outer supporting piece 14 is formed between the clamping space 5 and the outer force application space 11, the outer clamping portion 7 further comprises an outer fixing sleeve 15 fixedly arranged on the outer supporting piece 14 in a penetrating mode along the radial direction of the clamping space 5, the outer clamping head 9 is supported on the outer supporting piece 14 in a sliding mode through the outer fixing sleeve 15, the outer end of the outer fixing sleeve 15 is abutted to the outer ring of the outer force application space 11, and the outer end of the outer fixing sleeve 15 is arc-shaped.

As shown in fig. 4, the inner fixing sleeve 13 is formed with a first guide groove 16 extending along the radial direction of the clamping space 5 and having an outer end opened, the inner cartridge 8 is slidably fitted in the first guide groove 16, the outer end of the inner cartridge 8 extends from the outer end opening of the first guide groove 16 into the clamping space 5, the first guide groove 16 is internally sleeved with a first compression spring 17, the inner end of the first compression spring 17 abuts against the groove bottom of the first guide groove 16, the outer end of the first compression spring 17 abuts against the inner end of the inner cartridge 8, the outer fixing sleeve 15 is formed with a second guide groove 18 extending along the radial direction of the clamping space 5 and having an inner end opened, the outer cartridge 9 is slidably fitted in the second guide groove 18, the inner end of the outer cartridge 9 extends from the inner end opening of the second guide groove 18 into the clamping space 5, the second guide groove 18 is internally sleeved with a second compression spring 19, the outer end of the second compression spring 19 abuts against the groove bottom of the second guide groove 18, and the second compression spring 19 abuts against the outer end of the outer cartridge 9.

As shown in fig. 4, each of the first guide groove 16 and the second guide groove 18 includes a small diameter portion located on one side of the opening thereof and a large diameter portion located on the other side thereof, an annular end surface 23 is formed at the joint of the small diameter portion and the large diameter portion, a limiting protrusion 24 in sliding fit with the corresponding large diameter portion is respectively formed by extending the inner end of the inner collet 8 and the outer end of the outer collet 9 towards the respective radial outer side, the limiting protrusion 24 is cylindrical, the inner collet 8 and the outer collet 9 are respectively in sliding fit with the corresponding small diameter portion, and in an initial state, the outer end of the inner collet 8 is elastically abutted to the inner end of the outer collet 9.

As shown in fig. 1 and 2, an electromagnetic assembly 20 for generating a magnetic field in an area where the outer clamping head 9 is located is disposed outside the outer clamping portion 7, the electromagnetic assembly 20 includes a plurality of wires 21 laid in an outer ring wall of the outer force application space 11, the plurality of wires 21 extend in a circle along a circumferential direction of the outer force application space 11, the plurality of wires 21 are disposed at equal intervals along an axial direction of the outer force application space 11, the plurality of wires 21 are integrated with a cable connector 22 and connected with an external power source, and the outer clamping head 9 has magnetism to move inward or outward along a radial direction of the clamping space 5 under the action of electromagnetic force.

In the specific implementation of this embodiment, an operator inserts two end portions of a test piece into the clamping space 5 in the two clamp bodies 1, and inserts the tube wall of the test piece between the inner clamp 8 and the outer clamp 9 until the end surface of the test piece abuts against the outer end surface of the clamping space 5, the inner clamp 8 and the outer clamp 9 can apply a pretightening force to the tube wall of the test piece under the action of the first compression spring 17 and the second compression spring 19, at this time, the operator can adjust the clamping position of the test piece according to actual needs, after the clamping position is determined, the external power supply is turned on to supply a forward current to the lead 21, a magnetic field can be generated in the region where the outer clamp 9 is located, the outer clamp 9 moves inward along the radial direction of the clamping space 5 under the action of electromagnetic force, and applies a clamping force to the test piece by cooperating with the inner clamp 8 to realize stable clamping of the test piece, and then selects a proper connection end 2 according to the model of the fatigue testing machine, and then the connecting end 2 is connected with the output end of the fatigue testing machine, axial force is applied to the test piece through the fatigue testing machine to carry out tensile/compressive fatigue test, the fatigue performance of the test piece is detected according to the test result, and when the unloading operation is finished, the fatigue testing machine is stopped at first, and the inner pressure head and the outer pressure head move oppositely to achieve the unloading effect by changing the direction of current.

The utility model discloses can realize the even atress of test piece circumference to make the axis of test piece can coincide with the axis in centre gripping space behind the clamping, thereby can effectively guarantee the axiality of test piece and link, thereby can effectively prevent that the condition of off-axis from appearing in the test piece, thereby can guarantee that the test piece only receives the axial force in the testing process, can guarantee the accuracy that test piece fatigue performance detected from this.

Claims

1. The utility model provides a pipe test piece fatigue test anchor clamps which characterized in that: the clamp comprises two clamp bodies (1) which are arranged at left and right intervals and symmetrically, wherein each clamp body (1) comprises a connecting end (2) which is formed at the outer end of the clamp body and used for clamping a test piece on a testing machine and a clamping end (3) which is formed at the inner end of the clamp body and used for clamping the end part of the test piece, each clamping end (3) at least comprises a clamp seat (4), each clamp seat (4) is formed with a clamping space (5) which is provided with an inner end opening and is in a circular ring shape, the axis of each clamping space (5) is overlapped with the axis of the corresponding connecting end (2), the inner diameter of each clamping space (5) is smaller than the inner diameter of the test piece, the outer diameter of each clamping space (5) is larger than the outer diameter of the test piece, a plurality of inner clamping parts (6) used for being abutted against the inner ring of the test piece are arranged on one side of the inner ring of the clamping space (5), a plurality of outer clamping parts (7) used for being abutted against the outer ring of the test piece are arranged on one side of the outer ring of the clamping space (5), the inner clamping parts (6) and the outer clamping parts (7) are distributed in a circular array by taking the axis of the clamping space (5) as the center.

2. The round tube test piece fatigue test fixture of claim 1, characterized in that: interior clamping part (6) include interior chuck (8) at least, interior chuck (8) are indirectly or directly to be slided and are supported in centre gripping space (5) inner circle one side, interior chuck (8) can be followed the radial inside or outside removal of centre gripping space (5), outer clamping part (7) are including outer chuck (9) at least, outer chuck (9) are indirectly or directly to be slided and are supported in centre gripping space (5) outer lane one side, radial inside or outside removal that centre gripping space (5) can be followed in outer chuck (9).

3. The round tube test piece fatigue test fixture of claim 2, characterized in that: a plurality of interior clamping part (6) and a plurality of outer clamping part (7) one-to-one, interior chuck (8) in interior clamping part (6) and outer chuck (9) in the outer clamping part (7) that it corresponds move along the same radial line in centre gripping space (5).

4. The round tube test piece fatigue test jig according to claim 2 or 3, characterized in that: the clamp is characterized in that an inner force application space (10) and an outer force application space (11) which are respectively located on the radial inner side and the outer side of a clamping space (5) are further arranged in the clamp seat (4), the clamping space (5), the inner force application space (10) and the outer force application space (11) are all circular and the axes of the three coincide, a circular inner support (12) is formed between the clamping space (5) and the inner force application space (10), the inner clamping part (6) further comprises an inner fixing sleeve (13) which is fixedly arranged on the inner support (12) along the radial direction of the clamping space (5), the inner clamping head (8) is slidably supported on the inner support (12) through the inner fixing sleeve (13), a circular outer support (14) is formed between the clamping space (5) and the outer force application space (11), the outer clamping part (7) further comprises an outer fixing sleeve (15) which is fixedly arranged on the outer support (14) along the radial direction of the clamping space (5), the outer chuck (9) is supported on an outer supporting piece (14) in a sliding way through an outer fixing sleeve (15).

5. The round tube test piece fatigue test fixture of claim 4, characterized in that: the inner fixing sleeve (13) is provided with a first guide groove (16) which radially extends along the clamping space (5) and has an outer end open, the inner chuck (8) is slidably matched in the first guide groove (16), the outer end of the inner chuck (8) extends out of the outer end opening of the first guide groove (16) to the clamping space (5), the first guide groove (16) is internally sleeved with a first compression spring (17), the inner end of the first compression spring (17) is abutted against the groove bottom of the first guide groove (16), the outer end of the first compression spring (17) is abutted against the inner end of the inner chuck (8), the outer fixing sleeve (15) is provided with a second guide groove (18) which radially extends along the clamping space (5) and has an inner end open, the outer chuck (9) is slidably matched in the second guide groove (18), and the inner end of the outer chuck (9) extends out of the inner end opening of the second guide groove (18) to the clamping space (5), the second guide way (18) endotheca is equipped with second compression spring (19), the tank bottom butt of second compression spring (19) outer end and second guide way (18), the outer end butt of second compression spring (19) inner and outer chuck (9).

6. The round tube test piece fatigue test fixture of claim 5, characterized in that: the outer end of the inner chuck (8) is hemispherical, the inner end of the outer chuck (9) is in an arc shape matched with the outer ring of the test piece, and the outer end of the inner chuck (8) is elastically abutted to the inner end of the outer chuck (9) in an initial state.

7. The round tube test piece fatigue test fixture of claim 5, characterized in that: outer clamping part (7) outside is equipped with electromagnetic component (20) that are used for producing the magnetic field in the region at outer chuck (9) place, electromagnetic component (20) include many lay wire (21) in outer application of force space (11) outer lane wall body, many wire (21) extend the round along the circumference in outer application of force space (11), many axial equidistance interval setting along outer application of force space (11) is followed in wire (21), many wire (21) are integrated cable joint (22) and are linked to each other with external power source, outer chuck (9) have magnetism in order to follow radial inside or outside removal of clamping space (5) under the effect of electromagnetic force.

8. The round tube test piece fatigue test fixture of claim 5, characterized in that: first guide way (16) and second guide way (18) all are including the minor diameter portion that is located its opening one side and the major diameter portion of opposite side, the junction department of minor diameter portion and major diameter portion is formed with annular end face (23), interior chuck (8) inner and outer chuck (9) outer end are formed with respectively towards the radial outside extension separately with the spacing arch (24) of the major diameter portion sliding fit who corresponds, interior chuck (8) and outer chuck (9) are sliding fit with the minor diameter portion that corresponds respectively.

9. The round tube test piece fatigue test jig according to claim 1, 2, or 3, characterized in that: interior clamping part (6) and outer clamping part (7) are equipped with many circles along the axial equidistance interval of centre gripping space (5), the outer end of centre gripping space (5) seals and is formed with the plane.

10. The round tube test piece fatigue test jig according to claim 1, 2, or 3, characterized in that: the connecting end (2) is fixedly connected with the clamping end (3) in a detachable mode.