A special fixture for composite material cylinder axial compression test

Abstract

The present invention provides a special fixture for axial compression testing of composite cylinders, which relates to the field of test fixture technology. The fixture comprises: multiple flexible fixture groups and a base. Each flexible fixture group includes two oppositely positioned flexible fixtures. When clamping a composite cylinder, one flexible fixture in each flexible fixture group is located inside the composite cylinder, while the other is located outside. The two flexible fixtures can move toward each other to clamp the composite cylinder. The flexible fixture groups are slidably arranged on the base around the circumference and in the radial direction of the circumference. The solution provided by the present invention is simple in structure, easy to use, and can accommodate composite cylinders of various diameters.

Description

Technical Field

[0001] The invention relates to the technical field of test fixtures, in particular to a special fixture for composite material cylinder axial compression testing. Background Art

[0002] Carbon fiber composites, which use carbon fibers as reinforcement and a resin as a matrix, boast excellent properties such as high specific strength and high specific modulus, and are widely used in military, aviation, and industrial fields. In recent years, driven by the excellent energy absorption properties of composite materials and the demands of passive safety protection in areas such as automobiles and aircraft, domestic and international researchers have conducted a series of studies on the failure modes of composite cylinders under axial compression. Both experimental and theoretical analyses have focused on determining the buckling load of thin-walled composite cylinders under axial compression.

[0003] In the axial compression test of composite cylinders, composite cylinders are thin-walled parts, making clamping difficult. General fixtures cannot clamp composite cylinders. Existing fixtures specifically designed for axial compression tests of composite cylinders use several rigid blocks machined into arcs to tightly fit the cylinder so that the composite cylinder is clamped. When the cylinder size in the cylinder compression test needs to be changed, the blocks must be re-machined, resulting in poor adaptability and reduced production efficiency. For axial compression tests of thin-walled metal cylinders, the edges of the metal cylinders are mostly flange-type structures, with flanging machined on the edges and threaded holes machined on the flanging. When clamping, it is only necessary to bolt the metal cylinder to the compression testing machine. Composite cylinders are mostly fiber-wound structural parts. Due to the limitations of the fiber-wound process, it is impossible to machine a flanging structure like the edge of a metal cylinder. Therefore, composite cylinders cannot be clamped using the same clamping method as metal cylinders.

[0004] Therefore, it is very necessary to design a special fixture for composite cylinders with simple structure, easy use and strong adaptability. Summary of the Invention

[0005] The purpose of the present invention is to provide a special fixture for axial compression testing of composite material cylinders to solve the problems existing in the above-mentioned prior art. It has a simple structure, is easy to use and can adapt to composite material cylinders of various diameters.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a special fixture for axial compression testing of composite material cylinders, comprising: a plurality of flexible fixture groups and a base; each flexible fixture group includes two flexible fixtures arranged opposite to each other; when clamping the composite material cylinder, one flexible fixture in each flexible fixture group is located inside the composite material cylinder, and the other is located outside the composite material cylinder; the two flexible fixtures can move toward each other and clamp the composite material cylinder;

[0008] The flexible clamp group is slidably arranged on the base around the circumference and along the radial direction of the circumference.

[0009] Preferably, the base includes an annular support plate and a bottom plate, the annular support plate is fixedly arranged above the bottom plate, a chuck is arranged in the annular support plate, the chuck can be rotatably arranged on the bottom plate, the top surface of the chuck is provided with a planar thread, the flexible clamp group is provided on the movable claw, and the movable claw can be slidably arranged on the annular support plate; one end of the movable claw extends to protrude from the inner edge of the annular support plate, and a plurality of groove structures matching the planar thread are provided at the bottom of the movable claw, the movable claw is connected to the planar thread through a plurality of the groove structures, and when the chuck rotates, it drives the movable claw and the flexible clamp group to slide, and the chuck is driven to rotate by the rotation drive assembly.

[0010] Preferably, the rotation drive assembly includes a large bevel gear, a small bevel gear and a large handwheel, the large bevel gear is coaxial with the chuck and fixedly connected to the bottom of the chuck, the small bevel gear is meshed with the large bevel gear, and the large handwheel is connected to the small bevel gear through a connecting shaft. Rotating the large handwheel can drive the small bevel gear, the large bevel gear and the chuck to rotate in turn, and the large handwheel is located between the annular support plate and the bottom plate.

[0011] Preferably, a dovetail groove guide rail is provided on the top of the movable claw, and a dovetail groove slider is provided on the bottom of the two flexible clamps. The dovetail groove slider can be slidably set on the dovetail groove guide rail. A screw seat is also provided at the bottom of each flexible clamp, and the two screw seats are internally threaded with the same screw. The outer end of the screw is fixedly connected to a small handwheel, and rotating the small handwheel can drive the screw to rotate and thereby drive the two flexible clamps to move closer or farther away.

[0012] Preferably, a positioning pin is fixedly provided on the top of the movable claw between the two flexible clamps in each flexible clamp group.

[0013] Preferably, each of the flexible clamp groups is correspondingly provided with a pneumatic locker, and the pneumatic locker can lock the lead screw.

[0014] Preferably, the flexible clamp is a thimble-type flexible clamp.

[0015] Compared with the prior art, the present invention has achieved the following technical effects:

[0016] The special fixture for axial compression test of composite material cylinders of the present invention can adjust the position of the flexible fixture and utilize the characteristic that the flexible fixture can clamp special-shaped curved surfaces, so that the present invention can adapt to the clamping of composite material cylinders of different sizes.

[0017] In addition, the flat thread has its own radial locking function, and the screw is locked by a pneumatic locker, which makes the clamping force large, the clamping reliable, and the operation easy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a schematic structural diagram of a composite material cylinder being clamped by the special fixture for axial compression test of composite material cylinder provided by the present invention;

[0020] Figure 2 is a structural diagram of the flexible clamp group;

[0021] Figure 3 for Figure 2 A view in another direction;

[0022] Figure 4 Schematic diagram of the structure of the movable claw;

[0023] Figure 5 Schematic diagram of the structure of the annular support plate;

[0024] Figure 6 for Figure 5 Front view of

[0025] Figure 7 A half-section diagram of the special fixture for composite material cylinder axial compression test provided by the present invention;

[0026] In the figure: 1. Base plate; 2. Flange; 3. Annular support plate; 4. Flexible clamp group; 5. Composite material cylinder; 6. Large handwheel; 7. Small bevel gear rotating shaft; 8. Sliding bearing; 9. Small bevel gear; 10. Self-lubricating copper sleeve; 11. Large bevel gear rotating shaft; 12. Large bevel gear; 13. Chuck; 4-1. Small handwheel; 4-2. Screw seat; 4-3. Movable claw; 4-4. Flexible clamp; 4-5. Dovetail groove guide rail; 4-6. Dovetail groove slider; 4-7. Locating pin; 4-8. Screw; 4-9. Pneumatic locker. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] The purpose of the present invention is to provide a special fixture for axial compression testing of composite material cylinders to solve the problems existing in the above-mentioned prior art. It has a simple structure, is easy to use and can adapt to composite material cylinders of various diameters.

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] The present invention provides a special fixture for composite material cylinder axial compression test, such as Figures 1 to 7 As shown, it includes: multiple flexible clamp groups 4 and a base; each flexible clamp group 4 includes two flexible clamps 4-4 arranged opposite to each other. When clamping the composite material cylinder 5, one flexible clamp 4-4 in each flexible clamp group 4 is located inside the composite material cylinder 5, and the other is located outside the composite material cylinder 5. The two flexible clamps 4-4 can move toward each other and clamp the composite material cylinder 5;

[0031] The flexible clamp group 4 is slidably arranged on the base around the circumference and in the radial direction of the circumference.

[0032] By adjusting the position of each flexible clamp set 4 radially along the circumference, the clamp can accommodate composite cylinders 5 of varying sizes. The inner surface of each pair of flexible clamps 4-4 is shaped to adapt to the curved surface of the composite cylinder 5. Specifically, the flexible clamps 4-4 can be ejector pins or other flexible clamps. When the flexible clamps 4-4 are not clamped to the composite cylinder 5, the ejector pins are in a relaxed state. When the flexible clamps 4-4 are clamped, the ejector pins are in a fixed state, achieving adaptive clamping of the composite cylinder 5.

[0033] The special fixture for axial compression test of composite material cylinders of the present invention can adjust the position of the flexible fixture 4-4 and utilize the characteristic that the flexible fixture 4-4 can clamp special-shaped curved surfaces, so that the present invention can adapt to the clamping of composite material cylinders 5 of different sizes.

[0034] In some embodiments, in order to achieve the flexible clamp group 4 being able to be slidably arranged on the base around the circumference and along the radial direction of the circumference, the base includes an annular support plate 3 and a bottom plate 1, the annular support plate 3 is fixedly arranged above the bottom plate 1, and the support plate and the bottom plate 1 are fixedly connected by the middle flange 2, and a chuck 13 is arranged in the annular support plate 3, and the chuck 13 can be rotatably arranged on the bottom plate 1, and a flat thread is arranged on the top surface of the chuck 13, and the flexible clamp group 4 is arranged on the movable claw 4-3, and the movable claw 4-3 can be slidably arranged on the annular support plate 3; one end of the movable claw 4-3 extends to the inner edge protruding from the annular support plate 3, and a plurality of groove structures matching the flat thread are provided at the bottom of the movable claw 4-3, and the movable claw 4-3 is connected to the flat thread through a plurality of groove structures, and when the chuck 13 rotates, it drives the movable claw 4-3 and the flexible clamp group 4 to slide, and the chuck 13 is driven to rotate by the rotation drive assembly.

[0035] Among them, the rotation drive assembly includes a large bevel gear 12, a small bevel gear 9 and a large handwheel 6. The large bevel gear 12 is coaxial with the chuck 13 and is fixedly connected to the bottom of the chuck 13. The small bevel gear 9 is engaged with the large bevel gear 12. The large handwheel 6 is connected to the small bevel gear 9 through a connecting shaft. Rotating the large handwheel 6 can drive the small bevel gear 9, the large bevel gear 12 and the chuck 13 to rotate in turn. The large handwheel 6 is located between the annular support plate 3 and the base plate 1.

[0036] The large bevel gear 12 and the chuck 13 are connected together by screws. The self-lubricating copper sleeve 10 is installed on the base plate 1. The large bevel gear rotating shaft 11 and the self-lubricating copper sleeve 10 are coaxially connected. The self-lubricating copper sleeve 10 plays a role in reducing friction and lubricating.

[0037] In the solution provided by this embodiment, the planar thread has its own radial locking effect, thereby enhancing the stability of the clamping state of the clamp.

[0038] In some embodiments, in order to enable the two flexible clamps 4-4 in each flexible clamp group 4 to move closer to or away from each other, a dovetail groove guide rail 4-5 is provided on the top of the movable claw 4-3, and a dovetail groove slider 4-6 is provided at the bottom of the two flexible clamps 4-4. The dovetail groove slider 4-6 can be slidably set on the dovetail groove guide rail 4-5. A screw seat 4-2 is also provided at the bottom of each flexible clamp 4-4. The two screw seats 4-2 are internally threaded with the same screw 4-8. The outer end of the screw 4-8 is fixedly connected to a small handwheel 4-1. Rotating the small handwheel 4-1 can drive the screw 4-8 to rotate and thereby drive the two flexible clamps 4-4 to move closer or farther away.

[0039] In order to achieve locking, each flexible clamp group 4 is correspondingly provided with a pneumatic locker 4-9, which can lock the screw 4-8. After the adjustment is completed, the pneumatic locker 4-9 is used to lock the position of the screw 4-8. The pneumatic locker 4-9 can adopt any one of the existing technologies. In addition, in other embodiments, the screw 4-8 can also be manually locked by setting a top screw on the screw seat 4-2.

[0040] In some embodiments, a positioning pin 4 - 7 is fixedly provided on the top of the movable claw 4 - 3 between the two flexible clamps 4 - 4 in each flexible clamp group 4 , and the positioning pin 4 - 7 plays a centering role.

[0041] The device is operated by first placing the composite material cylinder 5 on the device, then turning the large handwheel 6 to drive the four flexible clamp groups 4 to move synchronously along the radial direction to a certain position, which makes the positioning pins 4-7 on the four flexible clamp groups 4 fit together with the inner arc surface or outer arc surface of the composite material cylinder 5. This process completes the centering process of the composite material cylinder 5 and the flexible clamp group 4. Then, the small handwheels 4-1 on the four flexible clamp groups 4 are turned respectively to rotate the screws 4-8 in the four flexible clamp groups 4, so that the ejector pins on the eight flexible clamps 4-4 fit together with the arc surface of the composite material cylinder 5. At the same time, the pneumatic locker 4-9 is used to lock the screws 4-8, thereby completing the clamping process of the composite material cylinder 5.

[0042] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A special fixture for composite material cylindrical axial compression test, characterized by: include:

18. The repairing kit for automotive dents, according to claim 1, wherein a bottom of the foot stand comprises a through-hole, and the two foot blocks are connected via a through-hole, and the two foot blocks are connected via a screw thread on the bottom of the foot stand, wherein the two foot blocks are connected via a screw thread on the bottom of the foot stand. The two foot blocks are connected via a screw thread on the bottom of the foot stand. The transmission gear of the present invention is connected with the gear of the gear train of described sliding panel and the gear of described sliding panel, and the transmission gear of described sliding panel is connected with the gear of described gear train.

2. The special fixture for composite material cylindrical axial compression test according to claim 1, characterized in that: A positioning pin is fixedly provided on the top of the movable claw between the two flexible clamps in each flexible clamp group.

3. The special fixture for composite material cylindrical axial compression test according to claim 1, characterized in that: Each of the flexible clamp groups is correspondingly provided with a pneumatic locker, and the pneumatic locker can lock the lead screw.

4. The special fixture for composite material cylindrical axial compression test according to claim 1, characterized in that: The flexible clamp is a thimble-type flexible clamp.

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