CN215525344U - Test device and test for test piece biaxial tension test - Google Patents
Test device and test for test piece biaxial tension test Download PDFInfo
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- CN215525344U CN215525344U CN202122055142.6U CN202122055142U CN215525344U CN 215525344 U CN215525344 U CN 215525344U CN 202122055142 U CN202122055142 U CN 202122055142U CN 215525344 U CN215525344 U CN 215525344U
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Abstract
The utility model relates to the technical field of material performance detection, and provides a test device for a biaxial tension test of a test piece, wherein an upper positioning component is arranged below an upper base plate, a lower positioning component is arranged above a lower base plate, and the upper positioning component and the lower positioning component are coaxially arranged up and down and are matched with each other for central positioning of the test piece; the axes of the upper positioning assembly and the lower positioning assembly of the four-gear rack assembly are arranged between the upper bottom plate and the lower bottom plate in an annular array mode with the axes as centers, the gear rack assembly is provided with a clamping end used for applying tensile force to the tensile fin, and during testing, bidirectional tensile force parallel to the plane where the test piece is located is applied to the test piece through the gear rack assembly; the strain acquisition assembly acquires strain of the test piece; the stress collection assembly collects the stress applied to the test piece by the clamping end. The quick positioning of the test piece can be realized through the upper and lower positioning assemblies, the positioning precision is high, the four-axis motion consistency can be ensured by adopting the gear rack mechanism, and the stress balance of the tensile test on the test piece is ensured.
Description
Technical Field
The utility model relates to the technical field of material performance detection, in particular to a test device for a biaxial tension test of a test piece.
Background
Before the material is applied to engineering, the performance of the material needs to be tested to judge whether the application requirements are met. Among these, the ability of a material to withstand tensile and fatigue loads in the axial direction is a relatively critical property. In the prior art, special testing machines such as a four-axis hydraulic testing machine, a two-axis testing machine (CN 107271287) and the like need to be used, so that the manufacturing cost is high and the use is complicated. When the universal testing machine is used, the test piece is not positioned in the center, and the four shafts do not move simultaneously, so that the problems of unbalance loading and the like are caused, and the test result is influenced; the upper and lower clamps have no guide device and the like, so that the repeatability of the test result is poor.
SUMMERY OF THE UTILITY MODEL
The technical problem to be solved by the utility model is as follows: in order to overcome the defects in the prior art, the utility model provides a test device and a test method for a biaxial tension test of a test piece.
The technical scheme adopted for solving the technical problems is as follows: a test piece biaxial tension test testing device is characterized in that a test piece is cross-shaped and comprises four tension fins, the upper side and the lower side of a common connecting end of the four tension fins are respectively provided with a positioning groove, the two side surfaces of each tension fin, which are close to one side of the connecting end, are provided with concave clamping surfaces, and speckles which can be identified by a camera are arranged in the positioning grooves below the test piece;
the testing device comprises an upper bottom plate, a lower bottom plate, an upper positioning assembly, a lower positioning assembly, four sets of gear rack assemblies, a strain acquisition assembly and a stress acquisition assembly, wherein the upper bottom plate and the lower bottom plate are arranged in parallel up and down and are used for supporting other assemblies and connecting with a testing machine; the upper positioning assembly is arranged below the upper base plate, the lower positioning assembly is arranged above the lower base plate, and the upper positioning assembly and the lower positioning assembly are coaxially arranged up and down and are matched with each other for central positioning of a test piece; the axes of the upper positioning assembly and the lower positioning assembly of the four groups of gear rack assemblies are arranged between the upper bottom plate and the lower bottom plate in an annular array mode with the centers as the centers, the gear rack assemblies are provided with clamping ends used for applying tensile force to tensile fins of a test piece, and during testing, bidirectional tensile force parallel to the plane of the test piece is applied to the test piece through the four groups of gear rack assemblies; the acquisition end of the strain acquisition assembly is arranged above or below the test piece and is used for acquiring the strain of the test piece; the stress acquisition assembly is arranged on the clamping end of the gear rack assembly and used for acquiring the stress applied to the test piece by the clamping end.
Further, in order to realize the synchronous action of the tensile force on the test piece, the gear rack assembly comprises a base, a gear, a vertical rack, a horizontal rack and a clamping block, wherein the bottom of the base is fixedly arranged in the limit groove of the lower bottom plate through a fixing screw, the base is arranged at the upper end of the base, and the base can be close to or far away from the central axis of the testing device along the radial direction, the upper end of the base is provided with a horizontal rack mounting part, the horizontal rack mounting part is provided with a T-shaped sliding groove, the extending direction of the sliding groove is parallel to the moving direction of the base, the horizontal rack is slidably mounted in the sliding groove, the tooth surface of the horizontal rack is upward, one end of the horizontal rack close to the central axis is fixedly connected with the clamping block for clamping the test piece, and the clamping block is provided with a clamping groove with a shape matched with that of the tensile fin of the test piece; the two sides of the horizontal rack mounting part are respectively provided with a side plate supporting platform extending in the same direction as the sliding groove, a side plate is mounted on the side plate supporting platform on each side, the side plates on the two sides are parallel to each other, the gear is rotatably connected between the two side plates through a gear shaft, the two ends of the gear shaft are respectively rotatably connected with the side plates through bearings, and the gear is arranged above the horizontal rack and meshed with the horizontal rack; a vertical rack is arranged on one side, close to the central axis, of the gear, the vertical rack is perpendicular to the horizontal rack, and the vertical rack is meshed with the gear; the upper end of the vertical rack is connected with the upper bottom plate through a fixing screw, and the connecting position of the vertical rack and the upper bottom plate can be adjusted; the lower end of the rack guide rod is movably connected with a guide pillar mounting hole in the base through the rack guide rod, the rack guide rod can move up and down along with the vertical rack in the guide pillar mounting hole, and the rack guide rod plays a role in guiding when the vertical rack moves up and down, so that the position of the vertical rack in the vertical direction is ensured, and the precision of torque transmission between the gear racks is ensured; when the vertical rack moves downwards, the horizontal rack is driven by the gear to be away from the central axis along the radial direction. Thereby through the upper plate and the lower plate between push down, drive vertical rack downstream to realize the drawing of grip block to the test piece.
Furthermore, in order to make the test piece center be located the axis of testing machine, still include adjustment mechanism, adjustment mechanism is used for realizing that the base is along radially being close to or keeping away from testing arrangement's axis on the base, adjustment mechanism is including setting up the boss mounting groove at the base top, sets up the regulation boss in the base bottom to and adjusting screw, adjust the boss setting in the boss mounting groove, the boss mounting groove is equipped with the opening towards the axis direction, is equipped with the through-hole on the base of opening one side dorsad, adjusting screw passes the regulation boss threaded connection in through-hole and the boss mounting groove. The movement of the adjusting boss in the boss mounting groove is realized by rotating the adjusting screw, so that the base drives the upper part of the base to be close to or far away from the central axis of the testing device along the radial direction, namely, the position of the center of the test piece is adjusted. The center of the test piece is positioned on the central axis of the testing machine, so that the balance of the force applied to the test piece by the testing machine can be ensured, and the testing precision and accuracy are improved.
Furthermore, in order to record and observe the strain condition of the test piece in the test process, a strain acquisition assembly is added, so that the strain acquisition assembly comprises a reflector and a camera, the reflector is obliquely arranged on a lower bottom plate below the test piece, an included angle between the reflector and the lower bottom plate is 45 degrees, the camera is arranged on the periphery of the reflector, and the camera is over against the direction of the reflected light of the reflector; in the stretching process, the area of speckles is arranged at the bottom of the test piece, the speckles are reflected to the camera through the reflector, and the deformation condition of the test piece due to stretching is shot through the camera, so that the strain in the stretching process of the test piece is obtained.
Further, in order to determine the corresponding relation between the strain and the stress, the stress acquisition assembly comprises a strain gauge, the strain gauge is attached to a clamping block between the horizontal rack and the clamping groove, and the strain gauge acquires the stress acting on the test piece on the clamping block. When the stress and the strain are collected, the stress and the strain are collected at the same time, so that the performance of the test piece material can be judged according to the corresponding conditions of the stress and the strain.
Furthermore, in order to ensure that the center of the test piece is positioned on a central axis of the testing machine, the upper positioning assembly comprises an upper positioning ring and an upper positioning rod, the upper end of the upper positioning ring is fixed below the upper bottom plate, an upper positioning cavity is arranged inside the upper positioning ring, the upper end of the upper positioning rod is inserted into the upper positioning cavity and can axially move along the upper positioning cavity, and the lower end of the upper positioning rod is provided with a positioning end matched with the positioning groove in shape; the side surface of the upper positioning ring is provided with a locking mechanism for locking the upper positioning rod in the upper positioning cavity;
the lower positioning assembly comprises a lower positioning ring and a lower positioning rod, the lower positioning ring is detachably connected to the upper surface of the lower bottom plate, and the lower positioning ring and the lower bottom plate can be in threaded connection; the lower positioning ring can be directly connected in a plugging mode, and the lower positioning ring can be stably connected to the lower bottom plate and can be conveniently detached through the matching precision of the hole diameters; a lower positioning cavity is arranged in the lower positioning ring, the lower end of the lower positioning rod is inserted in the lower positioning cavity and can axially move along the lower positioning cavity, and a positioning end matched with the positioning groove in shape is arranged at the upper end of the lower positioning rod; and the lower positioning component meets the following conditions:
(1) in order to realize the positioning effect of the lower positioning rod, after the top of the lower positioning rod is embedded into the positioning groove of the test piece, the height H1 from the top of the lower positioning rod to the bottom of the lower positioning ring is less than the sum of the heights of the lower positioning rod and the lower positioning ring, namely H1 is less than H1+ H2, wherein H1 is the height of the lower positioning rod, and H2 is the height of the lower positioning ring;
(2) after the lower positioning rod is inserted into the bottom of the lower positioning cavity, the height H3 from the top of the lower positioning rod to the bottom of the lower positioning ring is smaller than the height H2 from the upper surface of the lower base plate to the lower surface of the test piece.
Furthermore, in order to ensure the stability of the upper base plate in the pressing process, the guide device further comprises at least one group of guide assemblies, each group of guide assemblies comprises a guide pillar and a guide sleeve, an axial guide cavity is arranged in each guide sleeve, each guide cavity can be a through hole formed in each guide sleeve or a blind hole, one end of each guide pillar is inserted into each guide cavity and can move in each guide cavity along the axis direction, the other end of each guide pillar is fixed to one of the upper base plate and the lower base plate, and the other end of each guide sleeve is fixed to the other of the upper base plate and the lower base plate. The connection relation between the guide post and the guide sleeve of the positioning assembly and the upper bottom plate and the lower bottom plate is not unique, and can be determined according to design habits and actual conditions. Preferably, the guide assemblies are arranged in two groups and are symmetrically arranged between the upper base plate and the lower base plate on two sides of the test piece.
Furthermore, in order to ensure the connection stability of the guide pillar and the guide sleeve, a first limiting ring is arranged at the connection part of the guide pillar and the upper bottom plate or the lower bottom plate, and the first limiting ring is clamped on the upper bottom plate or the lower bottom plate; and/or a second limiting ring is arranged at the joint of the guide sleeve and the upper bottom plate or the lower bottom plate, and the second limiting ring is clamped on the upper bottom plate or the lower bottom plate.
Furthermore, in order to realize quick positioning and connection with the testing machine, an upper connecting rod is also arranged above the upper bottom plate, the upper connecting rod is fixedly connected to the upper bottom plate through an upper connecting rod positioning ring, and the upper end of the upper connecting rod is connected with the testing machine; a lower connecting rod is further arranged below the lower bottom plate, the lower connecting rod is fixedly connected to the lower bottom plate through a lower connecting rod positioning ring, and the lower end of the lower connecting rod is connected with the testing machine; and the upper connecting rod and the lower connecting rod are coaxially arranged.
A test method for a biaxial tension test of a test piece comprises the following steps:
s1: respectively installing an upper connecting rod on the upper bottom plate and a lower connecting rod on the lower bottom plate on the testing machine, and enabling the vertical rack of each group of gear rack assemblies to be meshed with the gear;
s2: an upper positioning rod is inserted into the upper positioning ring, the position of the upper positioning rod in the upper positioning ring can be adjusted up and down, a lower positioning rod is inserted into the lower positioning ring, the lower positioning ring inserted with the lower positioning rod is detachably connected to the lower bottom plate, and the position of the lower positioning rod in the lower positioning ring can be adjusted up and down;
s3: placing a test piece on a clamping block, respectively placing four tensile fins of the test piece in clamping grooves of the clamping block, and clamping the four tensile fins by using the clamping grooves;
s4: adjusting an adjusting screw of the rack and pinion assembly, wherein the base moves slowly on the base, so that the positioning groove on the upper end surface of the test piece is opposite to the positioning end of the upper positioning rod, and the positioning groove on the lower end surface of the test piece is opposite to the positioning end of the lower positioning rod; adjusting the heights of the upper positioning rod and the lower positioning rod simultaneously until the positioning ends of the upper positioning rod and the lower positioning rod are respectively and completely inserted into the positioning grooves on the two sides of the test piece;
s5: the base moves relative to the base, the bottom of the vertical rack is connected with the base, so that the vertical rack can synchronously move along with the base, and the upper end of the vertical rack is connected with the upper bottom plate, so that torsion can be generated at the joint of the vertical rack and the upper bottom plate, the vertical rack is deformed or bent, and the meshing precision and the transmission precision of the vertical rack and the gear are influenced;
s5: inserting a lower positioning rod to the bottom of a lower positioning ring, then taking down a lower positioning assembly from a lower bottom plate, simultaneously inserting an upper positioning rod to the top of an upper positioning ring, and fixing the upper positioning rod in the upper positioning ring through a locking mechanism on the side wall of the upper positioning ring;
s6: the method comprises the following steps of obliquely installing a reflector on a lower bottom plate right below a test piece, enabling an included angle between the reflector and the lower bottom plate to be 45 degrees, and enabling reflected light rays of the reflector to be right opposite to a lens of a camera;
s7: starting the testing machine to enable the upper base plate and the lower base plate to be close to each other, enabling the vertical rack to move in the vertical direction relative to the gear to drive the gear to rotate, so as to drive the horizontal rack meshed with the gear to move outwards, and applying stretching forces in two directions to the test piece through the clamping block connected with the horizontal rack; in the stretching process, the camera shoots the strain information of the bottom surface of the test piece in real time through the reflector and transmits the strain information to the data processing unit; meanwhile, the strain gauge on the clamping block measures the stress information applied on the test piece, and transmits the stress information to the data processing unit to complete the tensile test of the test piece.
The utility model has the beneficial effects that: the utility model provides a test device for a biaxial tension test of a test piece,
(1) the test piece is positioned in an auxiliary manner through the upper positioning assembly and the lower positioning assembly, so that the rapid center positioning of the test piece is realized;
(2) the testing device can be used for testing only in a universal testing machine or a compression testing machine, so that the requirement on the testing machine is reduced;
(3) a gear rack mechanism is used, and the relative motion of an upper bottom plate and a lower bottom plate is synchronously driven, so that the synchronous action of the tensile forces applied to four tensile fins on a test piece is ensured, and the consistency of the motion in four directions is ensured;
(4) a guide assembly consisting of a guide pillar and a guide sleeve is additionally arranged between the upper bottom plate and the lower bottom plate, so that the upper bottom plate and the lower bottom plate can be stably and accurately guided in the relative motion process.
Drawings
The utility model is further illustrated by the following figures and examples.
Fig. 1 is a schematic perspective view of a test piece.
Fig. 2 is a schematic view of the bottom structure of the test piece.
FIG. 3 is a schematic structural diagram of a biaxial tension test apparatus for a test piece according to the present invention.
Fig. 4 is a schematic structural diagram of a biaxial tension test testing device of a test piece of the present invention.
Fig. 5 is a schematic view of the axial cross-sectional structure of fig. 4.
FIG. 6 is a schematic structural view of a rack and pinion assembly.
FIG. 7 is a schematic structural view of a rack and pinion assembly.
Fig. 8 is a schematic view of the structure of the horizontal rack.
Fig. 9 is a schematic structural view of the base.
Fig. 10 is a schematic structural view of the base.
Fig. 11 is a schematic structural view of the upper jumper/lower jumper.
Fig. 12 is a schematic diagram of the working principle of the strain gauge assembly.
Fig. 13 is a schematic view of the position of the mirror.
FIG. 14 is a schematic view of the dimensional relationship between the lower positioning assembly and the test piece.
In the figure: 1-upper positioning ring, 2-upper positioning rod, 2-1-positioning end, 3-guide column, 4-rack and pinion assembly, 4-1-fixing screw, 4-2-vertical rack, 4-3-connecting pin, 4-4-clamping block, 4-5-horizontal rack, 4-51-tooth surface, 4-52-connecting hole, 4-53-rack sliding table, 4-54-groove and 4-55-U-shaped bayonet; 4-6-rack guide rod, 4-7-fixing screw, 4-8-base and 4-9-adjusting screw; 4-10-base, 4-101-chute, 4-102-side plate supporting platform, 4-103-adjusting boss, 4-104-adjusting threaded hole, 4-105-side plate mounting hole and 4-106-guide post mounting hole; 4-107-positioning pin holes, 4-11-positioning pins, 4-12-fixing screws, 4-13-side plates, 4-14-bearings, 4-15-gear shafts, 4-16-gears and 4-17-clamping grooves; 5-test piece, 5-1-stretching fin, 5-2-connecting end, 5-3-positioning groove, 5-4-clamping surface and 5-5-speckle; 6-lower positioning rod, 7-guide sleeve, 8-lower positioning ring, 9 a-upper connecting rod, 9 b-lower connecting rod, 10 a-upper connecting rod positioning ring, 10 b-lower connecting rod positioning ring, 11-lower bottom plate, 12-positioning screw, 13-upper bottom plate, 14-fixing screw, 15-reflector and 16-camera.
Detailed Description
The present invention will now be described in detail with reference to the accompanying drawings. This figure is a simplified schematic diagram, and merely illustrates the basic structure of the present invention in a schematic manner, and therefore it shows only the constitution related to the present invention.
As shown in fig. 1 and 2, which are schematic structural diagrams of a test piece 5, the test piece 5 is in a cross shape and includes four stretching fins 5-1, the upper and lower sides of a common connecting end 5-2 of the four stretching fins 5-1 are respectively provided with a positioning groove 5-3, the shape of the positioning groove 5-3 includes, but is not limited to, a circle, an ellipse, a polygon, and the like, as long as positioning in a horizontal plane and a vertical plane can be simultaneously achieved, i.e., center positioning is achieved, in this embodiment, it is preferable that the positioning groove 5-3 is in a rectangular shape, and the side wall is an inclined surface, so that the positioning ends 2-1 on the upper positioning rod 2 and the lower positioning rod 6 can be conveniently inserted, and the side wall at the front end of the positioning end 2-1 is also an inclined surface; two side faces of each stretching fin 5-1, which are close to one side of the connecting end 5-2, are provided with concave clamping surfaces 5-4, and speckles 5-5 capable of being recognized by a camera 16 are arranged in a positioning groove 5-3 below the test piece 5. In the drawing, F1 and F2 represent orthogonal (perpendicular to each other) stretching in two directions.
As shown in fig. 3-5, the test device for the biaxial tension test of the test piece of the present invention comprises an upper base plate 13, a lower base plate 11, an upper positioning assembly, a lower positioning assembly, four sets of rack and pinion assemblies 4, a strain acquisition assembly and a stress acquisition assembly, wherein the upper base plate 13 and the lower base plate 11 are arranged in parallel up and down, and are used for supporting other assemblies and connecting with a testing machine; the upper positioning assembly is arranged below the upper base plate 13, the lower positioning assembly is arranged above the lower base plate 11, and the upper positioning assembly and the lower positioning assembly are coaxially arranged up and down and are matched with each other for central positioning of the test piece 5; the axes of the upper positioning assembly and the lower positioning assembly of the four groups of gear rack assemblies 4 are arranged between the upper bottom plate 13 and the lower bottom plate 11 in an annular array mode, the gear rack assemblies 4 are provided with clamping ends used for applying tensile force to the tensile fins 5-1 of the test piece 5, and during testing, bidirectional tensile force parallel to the plane of the test piece 5 is applied to the test piece 5 through the four groups of gear rack assemblies 4; the acquisition end of the strain acquisition assembly is arranged above or below the test piece 5 and is used for acquiring the strain of the test piece 5; the stress acquisition assembly is arranged on the clamping end of the rack and pinion assembly 4 and is used for acquiring the stress applied to the test piece 5 by the clamping end.
In order to ensure the stability of the upper base plate 13 in the pressing process, the pressing device further comprises at least one group of guide assemblies, each group of guide assemblies comprises a guide pillar 3 and a guide sleeve 7, an axial guide cavity is arranged in each guide sleeve 7, each guide cavity can be a through hole formed in each guide sleeve 7 or a blind hole, one end of each guide pillar 3 is inserted into each guide cavity and can move in each guide cavity along the axis direction, the other end of each guide pillar 3 is fixed on one of the upper base plate 13 and the lower base plate 11, and the other end of each guide sleeve 7 is fixed on the other of the upper base plate 13 and the lower base plate 11. The connection relation between the guide post 3 and the guide sleeve 7 of the positioning component and the upper bottom plate 13 and the lower bottom plate 11 is not unique, and can be determined according to design habits and actual conditions. Preferably, the present embodiment has two sets of guiding assemblies symmetrically disposed between the upper base plate 13 and the lower base plate 11 on both sides of the test piece 5, and the guiding column 3 is connected to the upper base plate 13 and the guiding sleeve 7 is connected to the lower base plate 11. In order to ensure the connection stability of the guide pillar 3 and the guide sleeve 7, a first limiting ring is arranged at the connection part of the guide pillar 3 and the upper bottom plate 13, and the first limiting ring is clamped on the upper bottom plate 13; the joint of the guide sleeve 7 and the lower bottom plate 11 is provided with a second limiting ring, and the second limiting ring is clamped on the lower bottom plate 11.
In order to realize quick positioning and connection with the testing machine, an upper connecting rod 9a is further arranged above the upper bottom plate 13, the upper connecting rod 9a is fixedly connected to the upper bottom plate 13 through an upper connecting rod positioning ring 10a and a fixing screw 14, and the upper end of the upper connecting rod 9a is connected with the testing machine; a lower connecting rod 9b is further arranged below the lower bottom plate 11, the lower connecting rod 9b is fixedly connected to the lower bottom plate 11 through a lower connecting rod positioning ring 10b and a fixing screw, and the lower end of the lower connecting rod 9b is connected with a testing machine; and the upper connecting rod 9a and the lower connecting rod 9b are coaxially arranged.
As shown in fig. 6-10, the rack-and-pinion assembly 4 includes a base 4-8, a base 4-10, a gear 4-16, a vertical rack 4-2, a horizontal rack 4-5, and a clamping block 4-4, wherein the bottom of the base 4-8 is fixedly mounted in a limiting groove of the lower base plate 11 by a fixing screw 4-7, in this embodiment, four fixing screws 4-7 are provided, and arc-shaped avoiding grooves are provided at four corners of the limiting groove, so that the rectangular base 4-8 can be smoothly inserted into the limiting groove; the base 4-10 is installed at the upper end of the base 4-8, the base 4-8 can be close to or far away from the central axis of the testing device along the radial direction, and after the testing device is installed on the testing machine, the central axes of the testing device and the central axis of the testing device are overlapped. The upper end of the base 4-10 is provided with a horizontal rack 4-5 mounting part, the horizontal rack 4-5 mounting part is provided with a T-shaped sliding groove 4-101, the extending direction of the sliding groove 4-101 is parallel to the moving direction of the base 4-10, the horizontal rack 4-5 is slidably mounted in the sliding groove 4-101, a rack sliding table 4-53 of the horizontal rack 4-5 is embedded into the T-shaped sliding groove 4-101, and the tooth surface 4-51 of the horizontal rack 4-5 faces upwards. In order to reduce the resistance in the sliding process, the bottom surface of the horizontal rack 4-5 is provided with a groove 4-54 so as to reduce the contact area with the sliding chute 4-101 and reduce the friction force; one end of the horizontal rack 4-5 close to the central axis is provided with a U-shaped bayonet 4-55, the upper side wall and the lower side wall of the U-shaped bayonet 4-55 are provided with connecting holes 4-52 which are opposite, the end part of the clamping block 4-4 is inserted into the U-shaped bayonet 4-55, then the connecting pin 4-3 is inserted into the connecting hole 4-52, and the clamping block 4-4 for clamping the test piece 5 is fixed in the U-shaped bayonet 4-55; and the clamping block 4-4 is provided with a clamping groove 4-17 the shape of which is matched with that of the tensile fin 5-1 of the test piece 5. The two sides of the horizontal rack mounting part are respectively provided with a side plate supporting platform 4-102 extending in the same direction as the sliding groove 4-101, the side plate supporting platform 4-102 on each side is respectively provided with a side plate 4-13, the side plates 4-13 on the two sides are mutually parallel to clamp the horizontal rack mounting part in the middle, the side surface of the horizontal rack mounting part, which is attached to the side plates 4-13, is provided with a side plate mounting hole 4-105 for fixing the side plate 4-13, the side plate 4-13 and the horizontal rack mounting part are fixed through a fixing screw 4-12 connected into the side plate mounting hole 4-105 through a thread, and the bottom of the side plate 4-13 is supported on the side plate supporting platform 4-102. Positioning pins 4-11 are further arranged on the side plate 4-13 on one side, positioning pin holes 4-107 are further arranged between the two side plate mounting holes 4-105, when the side plates 4-13 are mounted, the positioning pins 4-11 are inserted into the positioning pin holes 4-107, and positioning between the base 4-10 and the side plates 4-13 can be achieved through the positioning pins 4-11; the gears 4-16 are rotatably connected between the two side plates 4-13 through gear shafts 4-15, two ends of the gear shafts 4-15 are respectively rotatably connected with the side plates 4-13 through bearings 4-14, and the gears 4-16 are arranged above the horizontal racks 4-5 and meshed with the horizontal racks 4-5; a vertical rack 4-2 is arranged on one side of the gear 4-16 close to the central axis, the vertical rack 4-2 is perpendicular to the horizontal rack 4-5, and the vertical rack 4-2 is meshed with the gear 4-16; the upper end of the vertical rack 4-2 is connected with the upper bottom plate 13 through a fixing screw 4-1, and the connecting position of the vertical rack and the upper bottom plate 13 can be adjusted; when the upper and lower positioning components are positioned, the fixing screw 4-1 can be in a locking state, and releases the torsion on the vertical rack 4-2 after the positioning is finished, or can be directly in an unscrewing state, directly and synchronously releases the torsion in the positioning adjustment process, and then is locked after the positioning is finished; the lower end of the rack guide rod is movably connected with a guide post mounting hole 4-106 on the base 4-10 through a rack guide rod 4-6, the rack guide rod 4-6 can move up and down along with the vertical rack 4-2 in the guide post mounting hole 4-106, and the rack guide rod 4-6 plays a role in guiding when moving up and down on the vertical rack 4-2, so that the position of the vertical rack 4-2 in the vertical direction is ensured, and the precision of torque transmission between the racks 4-16 of the gear is ensured; when the vertical rack 4-2 moves downwards, the horizontal rack 4-5 is driven by the gear 4-16 to be away from the central axis along the radial direction. Therefore, the vertical rack 4-2 is driven to move downwards by the downward pressing between the upper base plate 13 and the lower base plate 11, and the clamping block 4-4 stretches the test piece 5.
It should be noted that, the testing device needs to ensure that the movement distances and the strokes in the four directions are consistent in the using process, so that the gear 4-16, the horizontal rack 4-5 and the vertical rack 4-2 in the gear rack assembly 4 have certain requirements on the backlash in the design and assembly process, and the backlash needs to be zero or extremely small so as to eliminate the synchronous error of the movement distances in the four directions, and the backlash is preferably 0.02mm at most in the embodiment.
As shown in fig. 6, 7, 9 and 10, the rack-and-pinion assembly 4 further includes an adjusting mechanism, the adjusting mechanism is used for enabling the bases 4 to 10 to be close to or far away from the central axis of the testing device on the bases 4 to 8 along the radial direction, the adjusting mechanism includes a boss mounting groove (not shown in the figure) arranged at the top of the bases 4 to 8, adjusting bosses 4 to 103 arranged at the bottoms of the bases 4 to 10, and adjusting screws 4 to 9, the adjusting bosses 4 to 103 are arranged in the boss mounting groove, the boss mounting groove is provided with an opening facing the central axis direction, the bases 4 to 10 on the side facing away from the opening are provided with through holes, and the adjusting screws 4 to 9 pass through the through holes to be in threaded connection with the adjusting threaded holes 4 to 104 on the adjusting bosses 4 to 103. The adjusting bosses 4-103 move in the boss mounting grooves by rotating the adjusting screws 4-9 in the adjusting threaded holes 4-104, so that the base 4-10 drives the upper parts of the base 4-10 to be close to or far away from the central axis of the testing device along the radial direction, namely, the position of the center of the test piece 5 is adjusted. The center of the test piece 5 is positioned on the central axis of the testing machine, so that the balance of the force applied to the test piece 5 by the testing machine can be ensured, and the testing precision and accuracy are improved.
As shown in fig. 12 and 13, the strain acquisition assembly includes a reflector 15 and a camera 16, the reflector 15 is obliquely disposed on the lower base plate 11 below the test piece 5, an included angle between the reflector 15 and the lower base plate 11 is 45 °, the camera 16 is disposed at the periphery of the reflector 15, and the camera 16 faces the direction of the reflected light of the reflector 15; in the stretching process, the area of the speckle 5-5 arranged at the bottom of the test piece 5 is reflected to the camera 16 through the reflector 15, and the deformation condition of the test piece 5 due to stretching is shot through the camera 16, so that the strain amount of the test piece 5 in the stretching process is obtained.
In order to determine the corresponding relation between the strain and the stress, the stress acquisition assembly comprises a strain gauge which is attached to the clamping block 4-4 between the horizontal rack 4-5 and the clamping groove 4-17, and the strain gauge acquires the stress acting on the test piece 5 on the clamping block 4-4. When the stress and the strain are collected, the collection is carried out at the same time, so that the performance of the material of the test piece 5 can be judged according to the corresponding conditions of the stress and the strain. The specific location of the strain gage is not shown in the figures.
As shown in fig. 2 and 11, in order to ensure that the center of the test piece 5 is located on the central axis of the testing machine, the upper positioning assembly comprises an upper positioning ring 1 and an upper positioning rod 2, the upper end of the upper positioning ring 1 is fixed below the upper bottom plate 13, an upper positioning cavity is arranged inside the upper positioning ring 1, the upper end of the upper positioning rod 2 is inserted into the upper positioning cavity and can axially move along the upper positioning cavity, and the lower end of the upper positioning rod 2 is provided with a positioning end 2-1 which is matched with the positioning groove 5-3 in shape; the side surface of the upper positioning ring 1 is provided with a locking mechanism for locking the upper positioning rod 2 in the upper positioning cavity; the locking mechanism comprises a positioning screw 12 which is in threaded connection with the side wall of the upper positioning ring 1, and when the locking mechanism is locked, the positioning screw 12 is screwed inwards and abuts against the upper positioning rod 2; the lower positioning assembly comprises a lower positioning ring 8 and a lower positioning rod 6, the lower positioning ring 8 is detachably connected to the upper surface of the lower bottom plate 11, and the lower positioning ring 8 and the lower bottom plate 11 can be in threaded connection; the lower positioning ring 8 can be stably connected to the lower bottom plate 11 and can be conveniently detached through the matching precision of the hole diameters; a lower positioning cavity is arranged in the lower positioning ring 8, the lower end of the lower positioning rod 6 is inserted in the lower positioning cavity and can axially move along the lower positioning cavity, and a positioning end 2-1 matched with the positioning groove 5-3 in shape is arranged at the upper end of the lower positioning rod 6.
As shown in fig. 14, the lower positioning assembly satisfies the following condition:
(1) in order to realize the positioning effect of the lower positioning rod 6, after the top of the lower positioning rod 6 is embedded into the positioning groove 5-3 of the test piece 5, the height H1 from the top of the lower positioning rod 6 to the bottom of the lower positioning ring 8 is less than the sum of the heights of the lower positioning rod 6 and the lower positioning ring 8, namely H1 is less than H1 and H2, wherein H1 is the height of the lower positioning rod 6, and H2 is the height of the lower positioning ring 8;
(2) after the lower positioning rod 6 is inserted into the bottom of the lower positioning cavity, the height H3 from the top of the lower positioning rod 6 to the bottom of the lower positioning ring 8 is less than the height H2 from the upper surface of the lower bottom plate 11 to the lower surface of the test piece 5.
In this embodiment, the lower positioning cavity in the lower positioning ring 8 is a through hole, so H3 is also the height of the lower positioning rod 6, and it should be noted that when the lower positioning cavity is a blind hole, H3 is greater than the height of the lower positioning rod 6; h2 represents the height from the lower surface of the adjusted test piece 5 to the lower base plate 11; the requirement H3 < H2 is satisfied, and the lower positioning rod 6 and the lower positioning ring 8 can be taken down from the lower bottom plate 11 after the adjustment.
A test method for a biaxial tension test of a test piece comprises the following steps:
s1: respectively installing an upper connecting rod 9a on an upper bottom plate 13 and a lower connecting rod 9b on a lower bottom plate 11 on a testing machine, so that a vertical rack 4-2 and a gear 4-16 of each set of gear rack components 4 are meshed with each other;
s2: the upper positioning rod 2 is inserted into the upper positioning ring 1, the position of the upper positioning rod 2 in the upper positioning ring 1 can be adjusted up and down, the lower positioning rod 6 is inserted into the lower positioning ring 8, the lower positioning ring 8 inserted with the lower positioning rod 6 is detachably connected to the lower bottom plate 11, and the position of the lower positioning rod 6 in the lower positioning ring 8 can be adjusted up and down;
s3: placing a test piece 5 on a clamping block 4-4, respectively placing four tensile fins 5-1 of the test piece 5 in clamping grooves 4-17 of the clamping block 4-4, and tightly clamping by using the clamping grooves 4-17;
s4: adjusting screws 4-9 of the gear rack assembly 4, and slowly moving a base 4-10 on a base 4-8 to enable a positioning groove 5-3 on the upper end surface of the test piece 5 to be over against a positioning end 2-1 of the upper positioning rod 2 and enable a positioning groove 5-3 on the lower end surface of the test piece 5 to be over against a positioning end 2-1 of the lower positioning rod 6; simultaneously adjusting the heights of the upper positioning rod 2 and the lower positioning rod 6 until the positioning ends 2-1 of the upper positioning rod 2 and the lower positioning rod 6 are respectively and completely inserted into the positioning grooves 5-3 at the two sides of the test piece 5; the adjusting screws 4-9 are used for fine adjustment of the testing device.
S5: because the base 4-10 moves relative to the base 4-8, the bottom of the vertical rack 4-2 is connected with the base 4-10, therefore, the vertical rack can move synchronously with the base 4-10, the upper end of the vertical rack 4-2 is connected to the upper bottom plate 13, so that a torsion force is generated at the connection part of the vertical rack 4-2 and the upper bottom plate 13, which causes the vertical rack 4-2 to deform or bend, which affects the meshing precision and the transmission precision of the vertical rack 4-2 and the gear 4-16, therefore, after the position of the base 4-10 is adjusted, the fixing screw 4-1 connected with the upper bottom plate 13 at the upper end of the vertical rack 4-2 needs to be adjusted to release the torsion on the vertical rack 4-2, then, the vertical rack 4-2 is locked with the upper bottom plate 13 through a fixing screw 4-1;
s5: inserting a lower positioning rod 6 to the bottom of a lower positioning ring 8, then taking down a lower positioning assembly from a lower bottom plate 11, simultaneously inserting an upper positioning rod 2 to the top of an upper positioning ring 1, and fixing the upper positioning rod 2 in the upper positioning ring 1 through a locking mechanism on the side wall of the upper positioning ring 1;
s6: the reflector 15 is obliquely arranged on the lower bottom plate 11 right below the test piece 5, an included angle between the reflector 15 and the lower bottom plate 11 is 45 degrees, and the reflected light of the reflector 15 is right opposite to a lens of the camera 16;
s7: starting the testing machine to enable the upper base plate 13 and the lower base plate 11 to be close to each other, enabling the vertical rack 4-2 to move in the vertical direction relative to the gear 4-16 to drive the gear 4-16 to rotate, so as to drive the horizontal rack 4-5 meshed with the gear 4-16 to move outwards, and simultaneously applying stretching forces in two directions to the test piece 5 through the clamping block 4-4 connected with the horizontal rack 4-5; in the stretching process, the camera 16 shoots the strain information of the bottom surface of the test piece 5 in real time through the reflector 15 and transmits the strain information to the data processing unit; meanwhile, the strain gauge on the clamping block 4-4 measures the stress information applied on the test piece 5 and transmits the stress information to the data processing unit, and the tensile test of the test piece 5 is completed.
The testing machine performs the biaxial tension test at a compression rate of less than 10mm/min until the test piece 5 significantly yields or breaks, and preferably, at a compression rate of less than 5 mm/min. The material of the test piece 5 to be tested is determined according to actual test parts, and Unimax die steel (the hardness is more than HRC 52) is used for the rest structures, so that the rigidity is ensured.
The data processing unit can be a single chip microcomputer, a DSP or a computer, and realizes the processing and storage of data, and the data processing is irrelevant to the technical problem solved by the utility model, so the detailed description is omitted here.
In light of the foregoing description of preferred embodiments in accordance with the utility model, it is to be understood that numerous changes and modifications may be made by those skilled in the art without departing from the scope of the utility model. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.
Claims (9)
1. The utility model provides a test piece biaxial tension test testing arrangement which characterized in that: the test piece is cross-shaped and comprises four stretching fins, the upper side and the lower side of a common connecting end of the four stretching fins are respectively provided with a positioning groove, two side surfaces of each stretching fin, which are close to one side of the connecting end, are provided with concave clamping surfaces, and speckles capable of being recognized by a camera are arranged in the positioning grooves below the test piece;
the testing device comprises an upper bottom plate, a lower bottom plate, an upper positioning assembly, a lower positioning assembly, four sets of gear rack assemblies, a strain acquisition assembly and a stress acquisition assembly, wherein the upper bottom plate and the lower bottom plate are arranged in parallel up and down and are used for supporting other assemblies and connecting with a testing machine; the upper positioning assembly is arranged below the upper base plate, the lower positioning assembly is arranged above the lower base plate, and the upper positioning assembly and the lower positioning assembly are coaxially arranged up and down and are matched with each other for central positioning of a test piece; the axes of the upper positioning assembly and the lower positioning assembly of the four groups of gear rack assemblies are arranged between the upper bottom plate and the lower bottom plate in an annular array mode with the centers as the centers, the gear rack assemblies are provided with clamping ends used for applying tensile force to tensile fins of a test piece, and during testing, bidirectional tensile force parallel to the plane of the test piece is applied to the test piece through the four groups of gear rack assemblies; the acquisition end of the strain acquisition assembly is arranged above or below the test piece and is used for acquiring the strain of the test piece; the stress acquisition assembly is arranged on the clamping end of the gear rack assembly and used for acquiring the stress applied to the test piece by the clamping end.
2. The test piece biaxial tension test device according to claim 1, characterized in that: the gear rack assembly comprises a base, a gear, a vertical rack, a horizontal rack and a clamping block, wherein the base is fixedly installed on a lower bottom plate, the base is installed at the upper end of the base and can be close to or far away from a central axis of the testing device along the radial direction, a horizontal rack installation part is arranged at the upper end of the base, a T-shaped sliding groove is formed in the horizontal rack installation part, the extending direction of the sliding groove is parallel to the moving direction of the base, the horizontal rack is installed in the sliding groove in a sliding mode, the tooth surface of the horizontal rack faces upwards, one end, close to the central axis, of the horizontal rack is fixedly connected with the clamping block used for clamping a test piece, and a clamping groove with the shape matched with that of a tensile fin of the test piece is formed in the clamping block; side plate supporting tables extending in the same direction as the sliding grooves are arranged on two sides of the horizontal rack mounting part, a side plate is mounted on each side of each side plate supporting table, the gear is rotatably connected between the two side plates through a gear shaft, and the gear is arranged above the horizontal rack and meshed with the horizontal rack; a vertical rack is arranged on one side, close to the central axis, of the gear, the vertical rack is perpendicular to the horizontal rack, and the vertical rack is meshed with the gear; the upper end of the vertical rack is connected with the upper bottom plate through a fixing screw, and the connecting position of the vertical rack and the upper bottom plate can be adjusted; the lower end of the rack guide rod is movably connected with a guide pillar mounting hole on the base through a rack guide rod, and the rack guide rod can move up and down along with the vertical rack in the guide pillar mounting hole; when the vertical rack moves downwards, the horizontal rack is driven by the gear to be away from the central axis along the radial direction.
3. The test piece biaxial tension test device according to claim 2, characterized in that: still include adjustment mechanism, adjustment mechanism is used for realizing that the base is along radially being close to or keeping away from testing arrangement's axis on the base, adjustment mechanism sets up the regulation boss in the base bottom including setting up the boss mounting groove at the base top to and adjusting screw, adjust the boss setting in the boss mounting groove, the boss mounting groove is equipped with the opening towards the axis direction, is equipped with the through-hole on the base of opening one side dorsad, adjusting screw passes the regulation boss threaded connection in through-hole and the boss mounting groove.
4. The test piece biaxial tension test device according to claim 1, characterized in that: the strain acquisition assembly comprises a reflector and a camera, the reflector is obliquely arranged on the lower base plate below the test piece, an included angle between the reflector and the lower base plate is 45 degrees, the camera is arranged on the periphery of the reflector, and the camera is opposite to the direction of reflected light of the reflector.
5. The test piece biaxial tension test device according to claim 1, characterized in that: the stress acquisition assembly comprises a strain gauge, the strain gauge is attached to a clamping block between the horizontal rack and the clamping groove, and the strain gauge acquires stress acting on the test piece on the clamping block.
6. The test piece biaxial tension test device according to claim 1, characterized in that: the upper positioning assembly comprises an upper positioning ring and an upper positioning rod, the upper end of the upper positioning ring is fixed below the upper bottom plate, an upper positioning cavity is formed in the upper positioning ring, the upper end of the upper positioning rod is inserted in the upper positioning cavity and can axially move along the upper positioning cavity, and a positioning end matched with the positioning groove in shape is arranged at the lower end of the upper positioning rod; the side surface of the upper positioning ring is provided with a locking mechanism for locking the upper positioning rod in the upper positioning cavity;
the lower positioning assembly comprises a lower positioning ring and a lower positioning rod, the lower positioning ring is detachably connected to the upper surface of the lower bottom plate, a lower positioning cavity is formed in the lower positioning ring, the lower end of the lower positioning rod is inserted in the lower positioning cavity and can axially move along the lower positioning cavity, and a positioning end matched with the positioning groove in shape is arranged at the upper end of the lower positioning rod; and the lower positioning component meets the following conditions:
(1) after the top of the lower positioning rod is embedded into the positioning groove of the test piece, the height H1 from the top of the lower positioning rod to the bottom of the lower positioning ring is smaller than the sum of the heights of the lower positioning rod and the lower positioning ring, namely H1 is smaller than H1+ H2, wherein H1 is the height of the lower positioning rod, and H2 is the height of the lower positioning ring;
(2) after the lower positioning rod is inserted into the bottom of the lower positioning cavity, the height H3 from the top of the lower positioning rod to the bottom of the lower positioning ring is smaller than the height H2 from the upper surface of the lower base plate to the lower surface of the test piece.
7. The test piece biaxial tension test device according to claim 1, characterized in that: the guide assembly comprises a guide pillar and a guide sleeve, an axial guide cavity is formed in the guide sleeve, one end of the guide pillar is inserted into the guide cavity and can move in the guide cavity along the axis direction, the other end of the guide pillar is fixed to one of the upper base plate and the lower base plate, and the other end of the guide sleeve is fixed to the other of the upper base plate and the lower base plate.
8. The test piece biaxial tension test testing device of claim 7, characterized in that: a first limiting ring is arranged at the connecting position of the guide post and the upper bottom plate or the lower bottom plate, and the first limiting ring is clamped on the upper bottom plate or the lower bottom plate;
and/or a second limiting ring is arranged at the joint of the guide sleeve and the upper bottom plate or the lower bottom plate, and the second limiting ring is clamped on the upper bottom plate or the lower bottom plate.
9. The test piece biaxial tension test device according to claim 1, characterized in that: an upper connecting rod is further arranged above the upper bottom plate, the upper connecting rod is fixedly connected to the upper bottom plate through an upper connecting rod positioning ring, and the upper end of the upper connecting rod is connected with the testing machine;
a lower connecting rod is further arranged below the lower bottom plate, the lower connecting rod is fixedly connected to the lower bottom plate through a lower connecting rod positioning ring, and the lower end of the lower connecting rod is connected with the testing machine; and the upper connecting rod and the lower connecting rod are coaxially arranged.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116429573A (en) * | 2023-04-17 | 2023-07-14 | 北京工业大学 | Welding type IGBT module bonding wire tensile testing device and method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116429573A (en) * | 2023-04-17 | 2023-07-14 | 北京工业大学 | Welding type IGBT module bonding wire tensile testing device and method |
| CN116429573B (en) * | 2023-04-17 | 2023-12-08 | 北京工业大学 | Welding type IGBT module bonding wire tensile testing device and method |
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