CN114509359A - Cylinder pressure type fatigue loading device and loading method - Google Patents
Cylinder pressure type fatigue loading device and loading method Download PDFInfo
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- CN114509359A CN114509359A CN202210175129.0A CN202210175129A CN114509359A CN 114509359 A CN114509359 A CN 114509359A CN 202210175129 A CN202210175129 A CN 202210175129A CN 114509359 A CN114509359 A CN 114509359A
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- 238000011068 loading method Methods 0.000 title claims abstract description 73
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- 238000012360 testing method Methods 0.000 claims description 48
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- 230000033001 locomotion Effects 0.000 description 6
- 238000009661 fatigue test Methods 0.000 description 5
- 238000005299 abrasion Methods 0.000 description 3
- 230000001276 controlling effect Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 2
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/32—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces
- G01N3/36—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces generated by pneumatic or hydraulic means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M13/00—Testing of machine parts
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0001—Type of application of the stress
- G01N2203/0005—Repeated or cyclic
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0019—Compressive
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/003—Generation of the force
- G01N2203/0042—Pneumatic or hydraulic means
- G01N2203/0044—Pneumatic means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0073—Fatigue
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/026—Specifications of the specimen
- G01N2203/0262—Shape of the specimen
- G01N2203/0278—Thin specimens
- G01N2203/0282—Two dimensional, e.g. tapes, webs, sheets, strips, disks or membranes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Abstract
The invention provides a cylinder pressure type fatigue loading device and a loading method, wherein the cylinder pressure type fatigue loading device structurally comprises a main loading device; the main loading device comprises a cam mechanism, a cylinder (1), a lower piston (2-1), a lower piston mandril (2), an upper piston (5-1) and an upper piston mandril (5), the lower piston (2-1) and the upper piston (5-1) are positioned in the cylinder (1), an air pressure adjusting area is arranged between the lower piston (2-1) and the upper piston (5-1), the upper piston (5-1) is positioned above the lower piston (2-1), the upper surface of the upper piston (5-1) is connected with the lower end of an upper piston ejector rod (5), the upper piston ejector rod (5) penetrates through the top of the cylinder (1), the lower surface of the lower piston (2-1) is connected with the upper end of a lower piston ejector rod (2), the lower piston ejector rod (2) penetrates through the bottom of the cylinder (1), and the lower end of the lower piston ejector rod (2) is connected with the cam mechanism.
Description
Technical Field
The invention relates to a cylinder pressure type fatigue loading device and a loading method, and belongs to the field of structural experiment mechanics.
Background
In the engineering structures of aviation, navigation, traffic, roads and bridges, buildings and harbors, beams and elastic elements made of various materials are typical stressed components which are in a repeated stressed state under various environments for a long time, so that the fatigue strength of the components under various environments is an important research subject in structural mechanics; particularly, in modern engineering structure design, the strength problem of the component under complex environment and load must be researched, and the load and the environment state are urgently needed to be realized in a laboratory to check the fatigue strength of the component, so that preparation is made for the next theoretical establishment.
For a long time, it is very difficult to realize low-cost fatigue tests for the components, and the components can be realized by adopting a hydraulic servo fatigue testing machine at present, but because the equipment is expensive, the equipment has strict requirements on the use environment, has high energy consumption and needs high test cost for long-time use.
In the existing mechanical fatigue test loading devices, because displacement control loading is simply adopted, the deformation of a component is small in an elastic range, the precision of the load is completely realized by the displacement precision, and in addition, the abrasion of equipment in the fatigue test process cannot guarantee the precision requirement of the test load, so that the test effect is poor, particularly for small-size test pieces, the rigid impact of the component is large in the test process, and the noise of the device is large.
Disclosure of Invention
The invention provides a cylinder pressure type fatigue loading device and a loading method, and aims to solve the problems that the existing mechanical fatigue test loading device is loaded by displacement control only and different test piece loading requirements are not easy to solve.
The technical solution of the invention is as follows: a cylinder pressure type fatigue loading device structurally comprises a main loading device; the main loading device comprises a cam mechanism, a cylinder 1, a lower piston 2-1, a lower piston ejector rod 2, an upper piston 5-1 and an upper piston ejector rod 5, wherein the lower piston 2-1 and the upper piston 5-1 are positioned in the cylinder 1, an air pressure adjusting area is arranged between the lower piston 2-1 and the upper piston 5-1, the upper piston 5-1 is positioned above the lower piston 2-1, the upper surface of the upper piston 5-1 is connected with the lower end of the upper piston ejector rod 5, the upper piston ejector rod 5 penetrates through the top of the cylinder 1, the lower surface of the lower piston 2-1 is connected with the upper end of the lower piston ejector rod 2, the lower piston ejector rod 2 penetrates through the bottom of the cylinder 1, and the lower end of the lower piston ejector rod 2 is connected with the cam mechanism.
Further, the cylinder pressure type fatigue loading device structurally further comprises a load sensor 6, a test piece is connected with a fork lug 18; the load sensor 6 is connected with the upper end of the upper piston mandril 5, and the upper end of the upper piston mandril 5 is connected with the test piece connecting fork lug 18 through the load sensor 6.
Further, the cylinder pressure type fatigue loading device structurally further comprises a pressure regulating device; the pressure regulating device comprises a large pressure regulating system and a small pressure regulating system, the large pressure regulating system is communicated with the air pressure regulating area inside the air cylinder 1 through the first air duct 7, and the small pressure regulating system is communicated with the air pressure regulating area inside the air cylinder 1 through the second air duct 19.
Further, the cam mechanism comprises a cam plate 4 and a power source spindle 24, and the power source spindle 24 is coaxially connected with the cam plate 4; the cam disc 4 is oval as a whole; when the minor axis direction of the elliptic cam plate and the length direction of the lower piston mandril 2 are on the same straight line, the lower piston mandril 2 falls to the lowest position; when the long axis direction of the elliptic cam disc and the length direction of the lower piston mandril 2 are on the same straight line, one end of the long axis of the cam disc 4 pushes the lower piston mandril 2 to reach the highest position, and at the moment, the tested member is loaded through the lower piston mandril 2, the lower piston 2-1, the air pressure adjusting area, the upper piston 5-1, the upper piston mandril 5 and the load sensor 6; the lower end of the lower piston mandril 2 is provided with a roller 3, and the lower end of the lower piston mandril 2 is contacted with a cam disc 4 through the roller 3.
Further, the large pressure regulating system comprises a large pressure regulating cylinder 10, a large spiral type piston ejector rod 11, a large cylinder top cover 20, a large pressure regulating cylinder piston 11-1 and a gas storage tank 9, wherein the large pressure regulating cylinder 10 is communicated with the gas storage tank 9 through a third gas guide pipe 21, the gas storage tank 9 is communicated with the cylinder 1 through a first gas guide pipe 7, the edge of the large cylinder top cover 20 is fixed at the top of the large pressure regulating cylinder 10 through a plurality of large connecting bolts 13, the large pressure regulating cylinder piston 11-1 is located in the large pressure regulating cylinder 10, the upper surface of the large pressure regulating cylinder piston 11-1 is connected with the lower end of the large spiral type piston ejector rod 11, the large spiral type piston ejector rod 11 penetrates through the large cylinder top cover 20, a large rotating lever 12 is connected to the large spiral type piston ejector rod 11, and the large rotating lever 12 is located above the large pressure regulating cylinder 10.
Furthermore, the upper end of the large spiral type piston ejector rod 11 is provided with a hole with the diameter larger than that of the large rotary lever 12, the direction of the hole is vertical to the length direction of the large spiral type piston ejector rod 11, the large rotary lever 12 penetrates through the hole and penetrates through the large spiral type piston ejector rod 11, the side surface of the large spiral type piston ejector rod 11 is provided with an external thread, and the center part of the large cylinder top cover 20 is provided with a threaded hole matched with the external thread on the side surface of the large spiral type piston ejector rod 11; the first air duct 7 is connected with a barometer valve 8 in series, and a barometer is arranged at the barometer valve 8; and a cylinder barometer valve 14 is connected in series on the third air duct 21, and a barometer is also installed at the cylinder barometer valve 14.
Further, the small pressure regulating system comprises a small pressure regulating cylinder 15, a small spiral piston ejector rod 16, a small rotating lever 17, a small cylinder top cover 23 and a small pressure regulating cylinder piston 16-1, wherein the edge of the small cylinder top cover 23 is fixed at the top of the small pressure regulating cylinder 15 through a plurality of small connecting bolts 22, the small pressure regulating cylinder piston 16-1 is positioned in the small pressure regulating cylinder 15, the upper surface of the small pressure regulating cylinder piston 16-1 is connected with the lower end of the small spiral piston ejector rod 16, the small spiral piston ejector rod 16 penetrates through the small cylinder top cover 23, the small spiral piston ejector rod 16 is connected with the small rotating lever 17, the small rotating lever 17 is positioned above the small pressure regulating cylinder 15, and the small pressure regulating cylinder 15 is communicated with the inside of the cylinder 1 through a second air guide tube 19.
Furthermore, the upper end of the small spiral piston mandril 16 is provided with a hole with a diameter larger than that of the small rotary lever 17, the direction of the hole is vertical to the length direction of the small spiral piston mandril 16, the small rotary lever 17 penetrates through the hole and penetrates through the small spiral piston mandril 16, the side surface of the small spiral piston mandril 16 is provided with an external thread, and the central part of the small cylinder top cover 23 is provided with a threaded hole matched with the external thread on the side surface of the small spiral piston mandril 16; a small cylinder barometer valve 27 is connected in series on the second air duct 19, a barometer is also installed at the small cylinder barometer valve 27, and the small cylinder barometer valve 27 controls the air in the small pressure regulating cylinder 15 to be output to the cylinder 1.
A method for carrying out fatigue loading by using a cylinder pressure type fatigue loading device comprises the following steps:
(1) the lower piston mandril 2 in the cam mechanism is statically placed at an upward limit value as required, the position of a large rotating lever 12 in a large pressure regulating cylinder 10 is adjusted, the pressure in the cylinder 1 is changed, the numerical value of a load sensor 6 is read, and when the error between the numerical value of the load sensor 6 and the limit load value required to be loaded is within 5 percent, the large rotating lever 12 and a large cylinder top cover 20 are locked;
(2) and adjusting the position of a small rotating lever 17 in a small pressure adjusting cylinder 15, wherein the volumes of the large pressure adjusting cylinder 10 and the small pressure adjusting cylinder 15 are different, the small spiral type piston mandril 16 and the large spiral type piston mandril 11 descend by the same height, the pressure adjusting range of the small pressure adjusting cylinder 15 is smaller than that of the large pressure adjusting cylinder 10, further finely adjusting the pressure in the cylinder 1, and reading the value of the load sensor 6 until the loading requirement of the test piece is met.
A method for carrying out fatigue loading by using a cylinder pressure type fatigue loading device further comprises the following steps:
(3) when the test components made of different materials are required to be tested, and the limit load value is changed, the pressure of the air cylinder 1 is changed through the large pressure regulating system and the small pressure regulating system on the premise of not changing the structure of the hardware device, and the loading test requirement can be met.
The invention has the beneficial effects that:
1) the invention adopts the combination of mechanical motion and cylinder elements, realizes the repeated fatigue loading of structural elements such as beams, plates and the like through the linkage among the cam mechanism, the lower piston ejector rod, the upper piston and the upper piston ejector rod, and can meet the requirements of related experimental research;
2) the invention can greatly reduce the noise caused by the abrasion of structural elements and the impact of components and the load error caused by mechanical clearance, adopts a large pressure regulating system to greatly regulate the pressure of the cylinder, and adopts a small pressure regulating system to finely regulate the pressure of the cylinder, thereby being convenient to apply repeated fatigue loading with higher precision on the structural elements;
3) according to the invention, through the combination of mechanical motion and air pressure control elements, through a power source main shaft, a cam mechanism, a lower piston mandril, a cylinder, an upper piston and a lower piston, a sealing ring, a load sensor and a test piece loading connecting piece, the impact-free flexible repeated fatigue loading of structural elements such as beams, plates and the like is realized;
4) the invention adopts the cam mechanism to realize the position control test mode, and the loading device has simple structure, reliable performance and low equipment cost and is a low-energy-consumption product;
5) the invention can realize the adjustment of different fatigue loads by adopting a simple pressure regulating mode on the premise of not changing the hardware structure of the device, and can realize the change of loading conditions in the test process.
Drawings
FIG. 1 is a schematic structural diagram of the present invention.
Fig. 2 is a schematic view of the cam mechanism coupled to the lower piston rod.
Fig. 3 is a schematic diagram of the connection between the upper piston ram 5, the load cell 6, and the test piece attachment fork 18.
Fig. 4 is a schematic connection diagram between the large pressure regulating cylinder 10 and the large screw type piston mandril 11.
In the figure, 1 is a cylinder, 2 is a lower piston mandril, 2-1 is a lower piston, 3 is a roller, 4 is a cam plate, 5 is an upper piston mandril, 5-1 is an upper piston, 6 is a load sensor, 7 is a first air duct, 18 is a test piece connecting fork lug, 8 is a barometer valve, 9 is an air storage tank, 10 is a large pressure regulating cylinder, 11 is a large spiral piston mandril, 11-1 is a large pressure regulating cylinder piston, 12 is a large rotating lever, 13 is a large connecting bolt, 14 is a large cylinder barometer valve, 15 is a small pressure regulating cylinder, 16 is a small spiral piston mandril, 16-1 is a small pressure regulating cylinder piston, 17 is a small rotating lever, 18 is a test piece connecting fork lug, 19 is a second air duct, 20 is a large cylinder top cover, 21 is a third air duct, 22 is a small connecting bolt, 23 is a small air cylinder top cover, 24 is a power source main shaft, 25 is a shaft, 26 is a connecting bolt, 27 is a small cylinder barometer valve and 28 is a large piston ring.
Detailed Description
A cylinder pressure type fatigue loading device structurally comprises a main loading device; the main loading device comprises a cam mechanism, a cylinder 1, a lower piston 2-1, a lower piston ejector rod 2, an upper piston 5-1 and an upper piston ejector rod 5, wherein the lower piston 2-1 and the upper piston 5-1 are positioned in the cylinder 1, an air pressure adjusting area is arranged between the lower piston 2-1 and the upper piston 5-1, the upper piston 5-1 is positioned above the lower piston 2-1, the upper surface of the upper piston 5-1 is connected with the lower end of the upper piston ejector rod 5, the upper piston ejector rod 5 penetrates through the top of the cylinder 1, the lower surface of the lower piston 2-1 is connected with the upper end of the lower piston ejector rod 2, the lower piston ejector rod 2 penetrates through the bottom of the cylinder 1, and the lower end of the lower piston ejector rod 2 is connected with the cam mechanism.
The cylinder pressure type fatigue loading device structurally further comprises a load sensor 6, wherein the load sensor 6 is connected with the upper end of the upper piston mandril 5; the load sensor 6 is preferably a load cell.
The cylinder pressure type fatigue loading device structurally further comprises a test piece connecting fork lug 18, and the upper end of the upper piston mandril 5 is connected with the test piece connecting fork lug 18 through a load sensor 6.
The cylinder pressure type fatigue loading device structurally further comprises a pressure regulating device; the pressure regulating device comprises a large pressure regulating system and a small pressure regulating system, the large pressure regulating system is communicated with the inside of the cylinder 1 through the first air duct 7, and the small pressure regulating system is communicated with the inside of the cylinder 1 through the second air duct 19.
The big pressure regulating system is communicated with the air pressure regulating area inside the air cylinder 1 through the first air duct 7, and the small pressure regulating system is communicated with the air pressure regulating area inside the air cylinder 1 through the second air duct 19.
The cam mechanism comprises a cam plate 4 and a power source main shaft 24, and the power source main shaft 24 is coaxially connected with the cam plate 4; when the device works, the power source main shaft 24 is connected with an external power source, the external power source works to drive the power source main shaft 24 to rotate, the power source main shaft 24 drives the cam disc 4 to rotate, the cam disc 4 rotates to drive the lower piston mandril 2 and the lower piston 2-1 to move up and down, the reciprocating extrusion is continuously carried out on the air pressure adjusting area in the air cylinder 1 along with the up-and-down movement of the piston mandril 2 and the lower piston 2-1, the upper piston 5-1 and the upper piston mandril 5 can be driven to move up and down in the reciprocating extrusion process of the air pressure adjusting area, and the tested component is loaded through the upper piston mandril 5 and the load sensor 6, so that the fatigue strength test of the component is completed.
The external power source can be any one of all devices capable of providing power, such as a motor, a diesel engine, a gasoline engine and the like, and no special requirement is required for selection of the external power source.
The cam disc 4 is oval as a whole; when the minor axis direction of the elliptic cam plate and the length direction of the lower piston mandril 2 are on the same straight line, the lower piston mandril 2 falls to the lowest position; when the long axis direction of the elliptic cam disc and the length direction of the lower piston mandril 2 are on the same straight line, one end of the long axis of the cam disc 4 pushes the lower piston mandril 2 to reach the highest position, and at the moment, the tested member is loaded through the lower piston mandril 2, the lower piston 2-1, the air pressure adjusting area, the upper piston 5-1, the upper piston mandril 5 and the load sensor 6.
The lower end of the lower piston mandril 2 is provided with a roller 3, and the lower end of the lower piston mandril 2 is contacted with a cam disc 4 through the roller 3; the friction between the lower piston ram 2 and the cam disk 4 is reduced by the rollers 3.
The lower end of the lower piston mandril 2 is in clearance fit connection with the roller 3; preferably, the lower end of the lower piston mandril 2 is in clearance fit connection with the roller 3 through a shaft 25, the lower end of the lower piston mandril 2 is provided with a groove, the opening of the groove faces the cam disc 4, the shaft 25 and the roller 3 are both positioned in the groove, the shaft 25 penetrates through the central shaft of the roller 3, two ends of the shaft 25 are fixedly connected with the side wall of the groove, and the roller 3 can rotate around the shaft 25.
The load sensor 6 is provided with a threaded hole, the upper end part of the upper piston mandril 5 is provided with an external thread, and the upper piston mandril 5 is connected with the load sensor 6 through the matching of the external thread at the upper end part and the internal thread in the threaded hole; the upper surface of the load sensor 6 is fixedly connected with the test piece connecting fork lug 18, and preferably, the upper surface of the load sensor 6 is fixedly connected with the test piece connecting fork lug 18 through a connecting bolt 26; in use, the specimen attachment fork 18 is used to fixedly attach the test member.
The large pressure regulating system comprises a large pressure regulating cylinder 10, a large spiral type piston ejector rod 11, a large cylinder top cover 20, a large pressure regulating cylinder piston 11-1 and a gas storage tank 9, wherein the large pressure regulating cylinder 10 is communicated with the gas storage tank 9 through a third gas guide pipe 21, the gas storage tank 9 is communicated with the cylinder 1 through a first gas guide pipe 7, the edge of the large cylinder top cover 20 is fixed at the top of the large pressure regulating cylinder 10 through a plurality of large connecting bolts 13, the large pressure regulating cylinder piston 11-1 is positioned in the large pressure regulating cylinder 10, the upper surface of the large pressure regulating cylinder piston 11-1 is connected with the lower end of the large spiral type piston ejector rod 11, the large spiral type piston ejector rod 11 penetrates through the large cylinder top cover 20, a large rotating lever 12 is connected onto the large spiral type piston ejector rod 11, and the large rotating lever 12 is positioned above the large pressure regulating cylinder 10.
The upper end of the large spiral type piston ejector rod 11 is provided with a hole with the diameter larger than that of the large rotary lever 12, the direction of the hole is vertical to the length direction of the large spiral type piston ejector rod 11, the large rotary lever 12 penetrates through the hole to penetrate through the large spiral type piston ejector rod 11, the side surface of the large spiral type piston ejector rod 11 is provided with an external thread, and the central part of the large cylinder top cover 20 is provided with a threaded hole matched with the external thread on the side surface of the large spiral type piston ejector rod 11; when the large-spiral type piston ejector rod type load sensor works, the large-spiral type piston ejector rod 11 is in spiral connection with the large cylinder top cover 20, the large-spiral type piston ejector rod 11 is controlled to move upwards and downwards by rotating the large rotary lever 12, the large rotary lever 12 is rotated to drive the large-spiral type piston ejector rod 11 to rotate, the external thread of the large-spiral type piston ejector rod 11 is in spiral fit with the threaded hole in the center of the large cylinder top cover 20 to realize that the large-spiral type piston ejector rod 11 drives the large pressure regulating cylinder piston 11-1 to move upwards and downwards, and the load value of the load sensor 6 is roughly regulated.
The small pressure regulating system comprises a small pressure regulating cylinder 15, a small spiral piston ejector rod 16, a small rotating lever 17, a small cylinder top cover 23 and a small pressure regulating cylinder piston 16-1, wherein the edge of the small cylinder top cover 23 is fixed at the top of the small pressure regulating cylinder 15 through a plurality of small connecting bolts 22, the small pressure regulating cylinder piston 26-1 is positioned in the small pressure regulating cylinder 15, the upper surface of the small pressure regulating cylinder piston 16-1 is connected with the lower end of the small spiral piston ejector rod 16, the small spiral piston ejector rod 16 penetrates through the small cylinder top cover 23, the small rotating lever 17 is connected onto the small spiral piston ejector rod 16, the small rotating lever 17 is positioned above the small pressure regulating cylinder 15, and the small pressure regulating cylinder 15 is communicated with the inside of the cylinder 1 through a second air guide pipe 19.
The upper end of the small spiral piston mandril 16 is provided with a hole with the diameter larger than that of the small rotary lever 17, the direction of the hole is vertical to the length direction of the small spiral piston mandril 16, the small rotary lever 17 penetrates through the hole and penetrates through the small spiral piston mandril 16, the side surface of the small spiral piston mandril 16 is provided with an external thread, and the central part of the small cylinder top cover 23 is provided with a threaded hole matched with the external thread on the side surface of the small spiral piston mandril 16; when the fine-tuning load sensor works, the small spiral type piston ejector rod 16 is in spiral connection with the small cylinder top cover 23, the small rotary lever 17 is rotated to control the small spiral type piston ejector rod 16 to move upwards and downwards, the small rotary lever 17 is rotated to drive the small spiral type piston ejector rod 16 to rotate, the external thread of the small spiral type piston ejector rod 16 is in spiral fit with the threaded hole in the center of the small cylinder top cover 23 to achieve that the small spiral type piston ejector rod 16 drives the small pressure-regulating cylinder piston 16-1 to move upwards and downwards, and the fine tuning of the load value of the load sensor 6 is achieved.
The large pressure regulating cylinder piston 11-1 is contacted with the inner side wall of the large pressure regulating cylinder 10, and three circles of large piston rings 28 are sequentially arranged between the large pressure regulating cylinder piston 11-1 and the inner side wall of the large pressure regulating cylinder 10 to ensure air tightness; similarly, the small pressure regulating cylinder piston 16-1 is in contact with the inner side wall of the small pressure regulating cylinder 15, and three rings of small piston rings are sequentially arranged between the small pressure regulating cylinder piston 16-1 and the inner side wall of the small pressure regulating cylinder 15 to ensure air tightness.
The first air duct 7 is connected with a barometer valve 8 in series, and a barometer is arranged at the barometer valve 8; the third air duct 21 is connected with a big cylinder barometer valve 14 in series, and a barometer is also arranged at the big cylinder barometer valve 14; when the air pressure regulating device works, the big cylinder barometer valve 14 controls the air in the big pressure regulating cylinder 10 to be output to the air storage tank 9, and the barometer valve 8 controls the air in the air storage tank 9 to be output to the air cylinder 1.
A small cylinder barometer valve 27 is connected in series on the second air duct 19, a barometer is also installed at the small cylinder barometer valve 27, and the small cylinder barometer valve 27 controls the air in the small pressure regulating cylinder 15 to be output to the cylinder 1.
When the invention works: the cam mechanism is driven to rotate by an external power source, the long axis direction of the elliptic cam disc and the length direction of the lower piston ejector rod 2 are kept on the same straight line, and at the moment, the uppermost end of the long axis of the elliptic cam disc pushes the lower piston ejector rod 2 to rise to the highest position and keep still; then, the air pressure in an air pressure adjusting area in the air cylinder 1 is roughly adjusted through an air cylinder barometer valve 14 and an air cylinder barometer valve 8, the load pressure applied to a tested member by the upper piston mandril 2 through the load sensor 6 is continuously changed, the numerical value of the load sensor 6 is read, and the air cylinder barometer valve 14 and the air cylinder barometer valve 8 are closed when the error between the load value displayed by the load sensor 6 and the required loading limit load value is within 5 percent; then finely adjusting the gas pressure of the gas pressure adjusting area in the cylinder 1 through a small cylinder barometer valve 27, and finally closing the small cylinder barometer valve 27 when the load value of the load pressure applied to the tested member by the upper piston ejector rod 2 through the load sensor 6 reaches the loading limit load value required by the test requirement along with the change of the gas pressure adjusting area in the cylinder 1, so as to finish the test calibration of the gas pressure adjusting area in the cylinder 1; at the moment, the big cylinder barometer valve 14, the barometer valve 8 and the small cylinder barometer valve 27 are all in a closed state, an air pressure adjusting area in the cylinder 1 is a closed space, and then the fatigue loading test on a test member can be completed by controlling the rotation of the cam mechanism; when the load is applied to the tested member, the application speed of the load applied to the tested member can be realized only by changing the rotating speed of the cam mechanism, and the time from zero to the limit load value of the applied load can be conveniently adjusted.
When the fatigue loading test is carried out on a test member by using the device, because the test calibration of the air pressure adjusting area in the air cylinder 1 is finished before the test, the lower piston ejector rod 2 is controlled to ascend and descend only by controlling the rotation of the cam disc 4 in the cam mechanism, and when the lower piston ejector rod 2 ascends to the highest position, the fatigue loading of the test member is realized, because the test calibration is finished before, the air pressure adjusting area in the air cylinder 1 is in a closed state, and as long as the lower piston ejector rod 2 ascends to the highest position, the load value of the load pressure applied to the tested member by the upper piston ejector rod 2 through the load sensor 6 can be ensured to reach the limit load value required to be loaded by the test; as long as the test requirements of the tested member are unchanged, no matter how many same tested members are tested, the air pressure adjusting area in the air cylinder 1 does not need to be adjusted again, and the fatigue loading test of the tested member can be repeatedly realized only by controlling the cam mechanism; only when the type of the tested component and the test requirement are changed, the air pressure adjusting area in the air cylinder 1 needs to be tested and calibrated again through the large air cylinder barometer valve 14, the barometer valve 8 and the small air cylinder barometer valve 27.
The large and small of each component in the large and small pressure regulating systems are just comparison between the large and small pressure regulating systems, and no other special limitation is provided; such as: the diameter of a large pressure regulating cylinder 10 in a large pressure regulating system is larger than that of a small pressure regulating cylinder 15 in a small pressure regulating system, when a large spiral type piston mandril 11 and a small spiral type piston mandril 16 descend to the same height, the air pressure regulation generated in an air pressure regulating area in the air cylinder 1 is different through the large pressure regulating cylinder 10 and the small pressure regulating cylinder 15, the large pressure regulating system generates coarse regulation, and the small pressure regulating system generates fine regulation; the diameter of the large surge cylinder 10 is preferably 5 to 10 times, more preferably 5 or 10 times, the diameter of the small surge cylinder 15.
A method for carrying out fatigue loading by using a cylinder pressure type fatigue loading device comprises the following steps:
(1) the lower piston mandril 2 in the cam mechanism is statically placed at an upward limit value as required, the position of a large rotating lever 12 in a large pressure regulating cylinder 10 is adjusted, the pressure in the cylinder 1 is changed, the numerical value of a load sensor 6 is read, and when the error between the numerical value of the load sensor 6 and the limit load value required to be loaded is within 5 percent, the large rotating lever 12 and a large cylinder top cover 20 are locked;
(2) the position of a small rotating lever 17 in a small pressure regulating cylinder 15 is adjusted, the volumes of the large pressure regulating cylinder 10 and the small pressure regulating cylinder 15 are different, the small spiral type piston ejector rod 16 and the large spiral type piston ejector rod 11 descend by the same height, the pressure adjusting range of the small pressure regulating cylinder 15 is smaller than that of the large pressure regulating cylinder 10, the pressure in the cylinder 1 is further finely adjusted, the value of the load sensor 6 is read, and the loading requirement of a test piece is met.
A method for carrying out fatigue loading by using a cylinder pressure type fatigue loading device further comprises the following steps:
(3) when test components made of different materials are required to be tested, and the limit load value is changed, the loading test requirement can be met only by changing the pressure of the air cylinder 1 through the large pressure regulating system and the small pressure regulating system on the premise of not changing the structure of a hardware device; the device structure without changing hardware comprises devices without changing a cam mechanism, a cylinder 1, a lower piston 2-1, a lower piston mandril 2, an upper piston 5-1, an upper piston mandril 5, a load sensor 6 and the like.
The rotary cam mechanism is loaded by a power source, and the rotary motion is converted into linear reciprocating loading motion by the upper piston mandril 2; starting an external power source, and applying reciprocating flexible fatigue load to the test piece through a cam plate 4, a roller 3, a lower piston mandril 2, a lower piston 2-1, an upper piston mandril 5, an upper piston 5-1 and a load sensor 6 in sequence; reading barometer data at a barometer valve 14 of the large cylinder by adjusting the height of a large spiral type piston ejector rod 11 of the large pressure regulating cylinder 10, giving an air pressure value of the cylinder 1, and meeting the requirement of fatigue loading maximum load of a test piece under the condition of matching with the motion stroke of the cam plate 4; the height of a small spiral piston mandril 16 of the small pressure regulating cylinder 15 is adjusted, the air pressure value of the cylinder 1 is further regulated in a fine mode, and the accuracy of the load is guaranteed; the air storage tank ensures that the air pressure is stable during the loading period of the test piece; the invention can greatly reduce the load error caused by mechanical clearance, improves the load precision of the device through the air pressure regulation of the small pressure regulating device, meets the load loading requirements of different components on the premise of not changing the structure of the device, simultaneously reduces the noise problem caused by pure mechanical connection, and realizes the flexible repeated fatigue loading with higher precision on the structural original; in addition, the invention changes the traditional pure rigid connection mode by using the air pressure adjusting area in the air cylinder 1, reduces the abrasion among rigid parts by using the air pressure adjusting area, and prolongs the service life of the whole device.
Claims (10)
1. A cylinder pressure type fatigue loading device is characterized by comprising a main loading device; the main loading device comprises a cam mechanism, a cylinder (1), a lower piston (2-1), a lower piston mandril (2), an upper piston (5-1) and an upper piston mandril (5), the lower piston (2-1) and the upper piston (5-1) are positioned in the cylinder (1), an air pressure adjusting area is arranged between the lower piston (2-1) and the upper piston (5-1), the upper piston (5-1) is positioned above the lower piston (2-1), the upper surface of the upper piston (5-1) is connected with the lower end of an upper piston ejector rod (5), the upper piston ejector rod (5) penetrates through the top of the cylinder (1), the lower surface of the lower piston (2-1) is connected with the upper end of a lower piston ejector rod (2), the lower piston ejector rod (2) penetrates through the bottom of the cylinder (1), and the lower end of the lower piston ejector rod (2) is connected with the cam mechanism.
2. The cylinder pressure type fatigue loading device of claim 1, further comprising a load sensor (6), a test piece connecting fork lug (18); the load sensor (6) is connected with the upper end of the upper piston mandril (5), and the upper end of the upper piston mandril (5) is connected with the test piece connecting fork lug (18) through the load sensor (6).
3. The cylinder pressure type fatigue loading device of claim 1, further comprising a pressure regulating device; the pressure regulating device comprises a large pressure regulating system and a small pressure regulating system, the large pressure regulating system is communicated with an air pressure regulating area inside the air cylinder (1) through a first air duct (7), and the small pressure regulating system is communicated with the air pressure regulating area inside the air cylinder (1) through a second air duct (19).
4. A cylinder pressure type fatigue loading apparatus according to claim 1, wherein said cam mechanism comprises a cam plate (4) and a power source spindle (24), the power source spindle (24) is coaxially connected with the cam plate (4); the cam disc (4) is oval as a whole; when the minor axis direction of the elliptic cam disc and the length direction of the lower piston mandril (2) are on the same straight line, the lower piston mandril (2) falls to the lowest position; when the long axis direction of the elliptic cam disc and the length direction of the lower piston mandril (2) are on the same straight line, one end of the long axis of the cam disc (4) pushes the lower piston mandril (2) to reach the highest position, and at the moment, the load is applied to a tested member through the lower piston mandril (2), the lower piston (2-1), the air pressure adjusting area, the upper piston (5-1), the upper piston mandril (5) and the load sensor (6); the lower end of the lower piston ejector rod (2) is provided with a roller (3), and the lower end of the lower piston ejector rod (2) is contacted with a cam disc (4) through the roller (3).
5. The cylinder pressure type fatigue loading device according to claim 3, wherein the large pressure regulating system comprises a large pressure regulating cylinder (10), a large spiral type piston ejector rod (11), a large cylinder top cover (20), a large pressure regulating cylinder piston (11-1) and a gas storage tank (9), the large pressure regulating cylinder (10) is communicated with the gas storage tank (9) through a third gas guide pipe (21), the gas storage tank (9) is communicated with the cylinder (1) through a first gas guide pipe (7), the edge of the large cylinder top cover (20) is fixed at the top of the large pressure regulating cylinder (10) through a plurality of large connecting bolts (13), the large pressure regulating cylinder piston (11-1) is positioned in the large pressure regulating cylinder (10), the upper surface of the large pressure regulating cylinder piston (11-1) is connected with the lower end of the large piston ejector rod (11), and the large spiral type piston ejector rod (11) passes through the large cylinder top cover (20), the large spiral type piston mandril (11) is connected with a large rotating lever (12), and the large rotating lever (12) is positioned above the large pressure regulating cylinder (10).
6. The cylinder pressure type fatigue loading device according to claim 5, wherein the upper end of the large screw type piston ejector rod (11) is provided with a hole with a diameter larger than that of the large rotary lever (12), the direction of the hole is vertical to the length direction of the large screw type piston ejector rod (11), the large rotary lever (12) penetrates through the hole and penetrates through the large screw type piston ejector rod (11), the side surface of the large screw type piston ejector rod (11) is provided with an external thread, and the central part of the large cylinder top cover (20) is provided with a threaded hole matched with the external thread on the side surface of the large screw type piston ejector rod (11); the first air duct (7) is connected with a barometer valve (8) in series, and a barometer is arranged at the barometer valve (8); and an atmospheric cylinder barometer valve (14) is connected in series on the third air duct (21), and a barometer is also installed at the atmospheric cylinder barometer valve (14).
7. The cylinder pressure type fatigue loading device according to claim 3, wherein the small pressure regulating system comprises a small pressure regulating cylinder (15), a small spiral type piston ejector pin (16), a small rotating lever (17), a small cylinder top cover (23) and a small pressure regulating cylinder piston (16-1), the edge of the small cylinder top cover (23) is fixed on the top of the small pressure regulating cylinder (15) through a plurality of small connecting bolts (22), the small pressure regulating cylinder piston (16-1) is positioned in the small pressure regulating cylinder (15), the upper surface of the small pressure regulating cylinder piston (16-1) is connected with the lower end of the small spiral type piston ejector pin (16), the small spiral type piston ejector pin (16) penetrates through the small cylinder top cover (23), the small spiral type piston ejector pin (16) is connected with the small rotating lever (17), the small rotating lever (17) is positioned above the small pressure regulating cylinder (15), the small pressure regulating cylinder (15) is communicated with the interior of the cylinder (1) through a second air duct (19).
8. The cylinder pressure type fatigue loading device according to claim 7, wherein the upper end of the small screw type piston ejector rod (16) is provided with a hole with a diameter larger than that of the small screw type piston ejector rod (17), the direction of the hole is vertical to the length direction of the small screw type piston ejector rod (16), the small screw type piston ejector rod (16) penetrates through the hole and penetrates through the small screw type piston ejector rod (17), the side surface of the small screw type piston ejector rod (16) is provided with an external thread, and the central part of the small cylinder top cover (23) is provided with a threaded hole matched with the external thread on the side surface of the small screw type piston ejector rod (16); the second air duct (19) is connected with a small cylinder barometer valve (27) in series, a barometer is also installed at the small cylinder barometer valve (27), and the small cylinder barometer valve (27) controls the gas in the small pressure regulating cylinder (15) to be output to the cylinder (1).
9. A method for carrying out fatigue loading by using a cylinder pressure type fatigue loading device is characterized by comprising the following steps:
(1) the method comprises the steps that a lower piston mandril (2) in a cam mechanism is placed statically at an upward limit value as required, the position of a large rotating lever (12) in a large pressure regulating cylinder (10) is adjusted, the pressure in the cylinder (1) is changed, the numerical value of a load sensor (6) is read, and when the error between the numerical value of the load sensor (6) and the limit load value needing to be loaded is within 5%, the large rotating lever (12) and a top cover (20) of the large cylinder are locked;
(2) the position of a small rotating lever (17) in a small pressure regulating cylinder (15) is adjusted, the volumes of the large pressure regulating cylinder (10) and the small pressure regulating cylinder (15) are different, the small spiral type piston ejector rod (16) and the large spiral type piston ejector rod (11) descend to the same height, the pressure adjusting range of the small pressure regulating cylinder (15) is smaller than that of the large pressure regulating cylinder (10), the pressure in the cylinder (1) is further finely adjusted, and the numerical value of a load sensor (6) is read until the loading requirement of a test piece is met.
10. The method for fatigue loading by means of a cylinder pressure type fatigue loading device according to claim 9, further comprising:
(3) when test components made of different materials are required to be tested, and the limit load value is changed, the pressure of the air cylinder (1) is changed through the large pressure regulating system and the small pressure regulating system on the premise of not changing the structure of the hardware device, and the loading test requirement can be met.
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