High-temperature fatigue test device for metal bolt

Abstract

The invention discloses a high-temperature fatigue testing device for a metal bolt. The high-temperature fatigue testing device comprises a high-temperature fatigue testing machine and a fatigue testing clamp used in cooperation with the high-temperature fatigue testing machine. The fatigue test fixture comprises an upper fixture and a lower fixture which are used for fixing a bolt to be tested; a hydraulic jaw of a special testing machine is designed to be connected with a wedge-shaped conversion head, the wedge-shaped conversion head is used for replacing the jaw of the hydraulic clamp, and the wedge-shaped conversion head is connected with other clamps through a double-end stud. The problem that a hydraulic jaw only can be used for a sample is solved, a hydraulic clamp is converted into a mounting and replacing device for an equipment sensor and a bolt high-temperature connecting rod, and the problem that the high-temperature clamp can be mounted only by dismounting the hydraulic sensor is solved. The problem that a traditional clamp cannot be connected with a fastener is solved, a connector with a water cooling function is designed, the upper end of the connector is connected with a wedge-shaped adapter, and a T-shaped connecting groove is reserved in the lower end of the connector and used for achieving rapid mounting and dismounting of a high-temperature connecting block.

Description

Technical Field

[0001] The invention relates to the technical field of fatigue testing of metal bolts with a bolt shank length greater than 25 mm and a bolt shank diameter of 3 mm to 16 mm under tension-tension load and in a high temperature environment, and in particular to a high temperature fatigue testing device for metal bolts. Background Art

[0002] Bolts, as a universal connecting mechanical part, are widely used in many fields. For example, in the field of construction, high-rise buildings, bridges, stadiums, etc. all require a large number of steel structure bolts for connection to ensure the stability and safety of the buildings. In mechanical equipment and manufacturing industries, many equipment are connected by a large number of steel structure bolts, such as excavators, milling machines, punching machines, etc. These equipment need to withstand a lot of force and pressure, so the quality and reliability of steel structure bolts play a vital role in the normal operation of the equipment. In addition, in the fields of automobile manufacturing and shipbuilding, steel structure bolts are also an indispensable connection element, ensuring the firmness and safety of vehicles and ships. Therefore, accurate testing of the various performance indicators of bolts is an important means to guide the application of bolts and a key factor in ensuring the safety and stability of mechanical equipment.

[0003] In the national standard, GB / T 3908.1-2010 "Mechanical properties of fasteners - bolts, screws and studs" has detailed provisions on the basic properties of bolts such as strength, hardness, guaranteed load, carbonization and decarburization; GB / T13682-1992 "Axial load fatigue test method for threaded fasteners" has detailed provisions on the fatigue performance level SN curve test of bolts. In the field of modern mechanical engineering, the complexity of the use conditions of machinery and parts is increasing day by day. Many metal parts need to withstand high temperature environmental loads. Bolts, as the most commonly used connecting parts, are also subject to high temperature loads. Bolt high temperature fatigue refers to the process in which bolts gradually produce local permanent cumulative damage in one or several places under high temperature environment and cyclic stress, and cracks or sudden complete fractures occur after a certain number of cycles. Therefore, assessing the high temperature fatigue performance of bolts is an important means to assess the functional characteristics of bolts. Through fatigue testing, the fatigue life of bolts under specified environments and stress levels can be determined, the SN curve of materials can be drawn, and then the fatigue characteristics of materials can be evaluated.

[0004] High temperature fatigue testing machine is a machine mainly used to test the fatigue performance of metal and non-metal materials under tension, compression or tension and compression alternating loads at room temperature or high temperature. In the assembly state when high temperature testing is not performed, stress and strain control tests can be performed at room temperature. When high temperature testing is required, the hydraulic fixture needs to be removed and a high temperature resistant fixture needs to be installed. At the same time, a water cooling device needs to be installed on the high temperature furnace outside the high temperature fixture to prevent the high temperature from affecting the test machine sensor.

[0005] In actual work, traditional high temperature fixtures have great limitations when used for high temperature tests on metal bolts, as follows:

[0006] (1) Tool replacement is time-consuming and labor-intensive: The hydraulic fixture of the original machine has a connection force of 10 tons with the main machine. Each time the hydraulic fixture is disassembled and the high-temperature fixture is installed, it takes more than 5 hours. It also takes the same amount of time to replace the hydraulic fixture after the high-temperature test. This is dangerous and seriously restricts production efficiency.

[0007] (2) The original machine tooling cannot be used for high-temperature fatigue testing of bolts: The original machine's high-temperature connection tooling can only be used to clamp bars and plates, and cannot effectively connect bolts, nor can it be used for high-temperature fatigue testing of bolts;

[0008] (3) After the test of the traditional high-temperature fixture, it is necessary to wait for the fixture to cool down to a lower temperature before replacing the sample, which reduces the test efficiency. Summary of the invention

[0009] The purpose of the present invention is to provide a high-temperature fatigue testing device for metal bolts, which is used to solve the problem that the fatigue testing machine that needs to be used at normal temperature and high temperature takes a long time to replace the clamp and the traditional clamp cannot clamp the bolts. It provides a universal test tool that does not require disassembly of the original hydraulic clamp and can complete the rapid disassembly and installation of bolts in a high temperature environment.

[0010] To achieve the purpose of the present invention, the technical solution provided by the present invention is as follows:

[0011] A high temperature fatigue test device for metal bolts, comprising a high temperature fatigue test machine and a fatigue test fixture used in conjunction with the same;

[0012] The fatigue test fixture comprises an upper fixture and a lower fixture for fixing the bolt to be tested;

[0013] The upper fixture includes a first conversion connection stud, a first water-cooled connecting head, a first high-temperature rod connecting block and a first high-temperature resistant connecting rod, a high-temperature resistant conversion head, and a high-temperature resistant bolt upper connecting body connected in sequence, one end of the first conversion connection stud is threadedly connected to one end of the first water-cooled connecting head, the first water-cooled connecting head is provided with a first T-slot, and is connected to the T-rod end of the first high-temperature rod connecting block through the first T-slot, the first high-temperature rod connecting block is threadedly connected to one end of the first high-temperature resistant connecting rod, and the first high-temperature resistant connecting rod is sleeved with a first heat insulating sleeve, the first high-temperature resistant connecting rod is connected to one end of the high-temperature resistant conversion head, and the other end of the high-temperature resistant conversion head is threadedly connected to the high-temperature resistant bolt upper connecting body;

[0014] The lower fixture comprises a second conversion connection stud, a second water-cooling connection head, a second high-temperature rod connection block, a second high-temperature resistant connection rod, and a high-temperature resistant bolt lower connection body which are connected in sequence;

[0015] One end of the second conversion connection stud is threadedly connected to one end of the second water-cooling connection head, a second T-slot is provided on the second water-cooling connection head, and the second T-slot is connected to the T-rod end of the second high-temperature rod connection block, the second high-temperature rod connection block is threadedly connected to one end of the second high-temperature resistant connecting rod, and a second heat-insulating sleeve is sleeved on the second high-temperature resistant connecting rod, and the second high-temperature resistant connecting rod is threadedly connected to the lower connector of the high-temperature resistant bolt;

[0016] The high temperature resistant bolt upper connector is provided with a cavity with one side open, and one end of the cavity is provided with a through hole for the tested bolt to pass through. After the tested bolt passes through the through hole, it is threadedly connected with one end of the high temperature resistant bolt lower connector.

[0017] Wherein, the first conversion connection stud and the second conversion connection stud are respectively connected to the first wedge-shaped conversion head and the second wedge-shaped conversion head.

[0018] A cooling cavity is provided inside the first water-cooling connector, and the cooling cavity is connected to a water-cooling pipeline via two first water-cooling nozzles provided on both sides.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention solves the problem of poor versatility of traditional clamps by the following measures:

[0021] Design a wedge-shaped conversion head to connect the hydraulic jaws of a special testing machine, use the wedge-shaped conversion head to replace the jaws of the hydraulic fixture, and connect the wedge-shaped conversion head to other fixtures through studs. Solve the problem that the hydraulic jaws can only hold samples, transform the hydraulic fixture into a replacement device for the equipment sensor and the high-temperature connecting rod of the bolt, and solve the problem that the hydraulic sensor needs to be removed before the high-temperature fixture can be installed;

[0022] 2. The present invention solves the problem that the traditional clamp cannot connect the fastener by the following measures:

[0023] Design a water-cooled connector, the upper end is connected to the wedge-shaped conversion head, and the lower end is reserved with a T-shaped connection groove for quick installation and removal with the high-temperature connection block;

[0024] 3. The present invention solves the connection problem between the bolt and the traditional clamp by the following measures:

[0025] Design high temperature rod connection block, high temperature resistant connection head, high temperature resistant connection rod, high temperature resistant bolt upper / lower connection body to realize the rapid disassembly and assembly connection between tooling that withstands high temperature environment and water cooling connection head;

[0026] 4. The present invention solves the problem of having to wait for the sample to cool to a lower temperature before replacing the sample after a high temperature test by the following measures:

[0027] Design multiple sets of high-temperature rod connecting blocks, high-temperature resistant connecting heads, high-temperature resistant connecting rods, and high-temperature resistant bolt upper / lower connecting body tooling. The tooling can be installed as a whole into the upper and lower fixtures of the testing machine through T-slots. The connecting part is outside the high-temperature furnace. The tested sample can be removed together with the tooling as a whole to a safe area to wait for cooling. The new sample to be tested and the tooling can be replaced and installed as a whole into the upper and lower T-slots of the testing machine. There is no need to operate in the high-temperature furnace, which saves the waiting time for high-temperature cooling and improves the safety of high-temperature operation.

[0028] On the basis of the above, the present invention realizes the connection between the hydraulic clamp and the high-temperature clamp without removing the normal-temperature hydraulic clamp, thus avoiding the tedious process of repeatedly replacing the clamp and greatly improving the work efficiency;

[0029] In addition, the present invention solves the connection problem between the metal bolt and the testing machine in the high-temperature furnace. By processing the upper / lower connectors of high-temperature resistant bolts of different specifications, fatigue testing of high-temperature resistant bolts of all specifications with a length exceeding 15 mm and a specification below M16 can be achieved.

[0030] In addition, the invention solves the problem that after the test, the metal high-temperature fatigue sample needs to wait to cool to a lower temperature before the sample can be replaced in the high-temperature furnace. The overall disassembly and installation of the high-temperature resistant part can be achieved through the T-shaped connecting groove, which greatly improves the work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the structure of a fatigue test fixture provided in an embodiment of the present application;

[0032] In the figure, the upper fixture 10, the heating unit 8, and the lower fixture 9;

[0033] Figure 2 A schematic diagram of a portion of the structure of the upper clamp provided in an embodiment of the present application;

[0034] In the figure, a first high temperature resistant connecting rod 6 and a first heat insulating sleeve 7;

[0035] Figure 3 A schematic diagram of the structure of a first water-cooling connector provided in an embodiment of the present application;

[0036] In the figure, the first water cooling connector 3, the first T-slot 4, the first water cooling nozzle 5;

[0037] Figure 4 A schematic diagram of the connection structure between the first wedge-shaped conversion head and the first conversion connection stud provided in an embodiment of the present application;

[0038] In the figure, the first wedge-shaped conversion head 1, the first conversion connection stud 2;

[0039] Figure 5 A schematic diagram of the structure of a first high-temperature rod connecting block provided in an embodiment of the present application;

[0040] Figure 6 A schematic diagram of the structure of a first thermal insulation sleeve provided in an embodiment of the present application;

[0041] Figure 7 A schematic structural diagram of a first high temperature resistant connecting rod provided in an embodiment of the present application;

[0042] Figure 8 A schematic diagram of the structure of a first high temperature resistant conversion head provided in an embodiment of the present application;

[0043] Fig. 9 A schematic diagram of the assembly structure of a high temperature resistant bolt upper connector and a high temperature resistant bolt lower connector provided in an embodiment of the present application;

[0044] In the figure, there is a high temperature resistant bolt upper connector 11, a bolt to be tested 12, and a high temperature resistant bolt lower connector 13. DETAILED DESCRIPTION

[0045] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0046] like Figure 1-Figure 9 The structure of the embodiment of the present application is shown.

[0047] This embodiment provides a high temperature fatigue test device for metal bolts, including a high temperature fatigue test machine and a fatigue test fixture used in conjunction with it;

[0048] The fatigue test fixture comprises an upper fixture 10 and a lower fixture 9 for fixing a bolt 12 to be tested;

[0049] The upper fixture 10 includes a first conversion connection stud 2, a first water-cooling connection head 3, a first high-temperature rod connecting block and a first high-temperature resistant connecting rod 6, a high-temperature resistant conversion head, and a high-temperature resistant bolt upper connector 11, which are connected in sequence. One end of the first conversion connection stud 2 is threadedly connected to one end of the first water-cooling connection head 3. The first water-cooling connection head 3 is provided with a first T-slot 4, which is connected to the T-rod end of the first high-temperature rod connecting block through the first T-slot 4. The first high-temperature rod connecting block is threadedly connected to one end of the first high-temperature resistant connecting rod 6, and the first high-temperature resistant connecting rod 6 is sleeved with a first heat insulation sleeve 7. The first high-temperature resistant connecting rod 6 is connected to one end of the high-temperature resistant conversion head, and the other end of the high-temperature resistant conversion head is threadedly connected to the high-temperature resistant bolt upper connector 11;

[0050] The lower fixture comprises a second conversion connection stud, a second water-cooling connection head, a second high-temperature rod connection block, a second high-temperature resistant connection rod, and a high-temperature resistant bolt lower connection body 13 which are connected in sequence;

[0051] One end of the second conversion connection stud is threadedly connected to one end of the second water-cooling connector, a second T-slot is provided on the second water-cooling connector, and the second T-slot is connected to the T-rod end of the second high-temperature rod connecting block, the second high-temperature rod connecting block is threadedly connected to one end of the second high-temperature resistant connecting rod, and a second heat-insulating sleeve is sleeved on the second high-temperature resistant connecting rod, and the second high-temperature resistant connecting rod is threadedly connected to the high-temperature resistant bolt lower connector 13;

[0052] The high temperature resistant bolt upper connector 11 is provided with a cavity with one side open, and one end of the cavity is provided with a through hole for the tested bolt 12 to pass through. After the tested bolt 12 passes through the through hole, it is threadedly connected with one end of the high temperature resistant bolt lower connector 13.

[0053] Wherein, the first conversion connection stud 2 and the second conversion connection stud are respectively connected to the first wedge-shaped conversion head 1 and the second wedge-shaped conversion head.

[0054] A cooling cavity is provided inside the first water-cooling connector 3 , and the cooling cavity is connected to a water-cooling pipeline via two first water-cooling nozzles 5 provided on both sides.

[0055] It should be noted that the heating unit 8 covers the bolt to be tested with a heat insulating sleeve, thereby effectively performing heat insulation.

[0056] It should be noted that the first wedge-shaped conversion head 1 has the same structure as the second wedge-shaped conversion head; the first conversion connection stud 2 has the same structure as the second first conversion connection stud, and the double ends have a threaded connection structure; the first water-cooling connection head 3 has the same structure as the second water-cooling connection head; the first high-temperature rod connection block has the same structure as the second high-temperature rod connection block; the first high-temperature resistant connection rod 6 has the same structure as the second high-temperature resistant connection rod; the high-temperature resistant conversion head has a double-headed threaded connection structure;

[0057] It should be noted that the water cooling nozzle is used to connect the cooling water inlet and outlet; the insulation sleeve is used to isolate the high-temperature furnace from the external space.

[0058] Experimental process:

[0059] 1: Select the appropriate high-temperature bolt connector according to the specifications and dimensions of the sample;

[0060] 2: Connect the sample through the high temperature connector and other test fixtures of the present invention and place it in a high temperature furnace;

[0061] 3: Heat and keep the sample warm according to the test temperature given by the customer;

[0062] 4: Carry out fatigue test according to the stress conditions given by the customer;

[0063] 5: After the test, record the results and replace the sample to continue the test.

[0064] It should be noted that the high temperature fatigue testing machine adopts the equipment in the prior art, and its structure and working principle are not described in detail.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate and explain the present invention, and are not intended to limit the present invention to the scope of the described embodiments. In addition, those skilled in the art can understand that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of the protection claimed by the present invention.

Claims

1. A high temperature fatigue test device for metal bolts, characterized in that: Including high temperature fatigue testing machine and fatigue testing fixture used in conjunction with it; The fatigue test fixture comprises an upper fixture (10) and a lower fixture (9) for fixing a bolt (12) to be tested; The upper clamp (10) comprises a first conversion connection stud (2), a first water-cooling connection head (3), a first high-temperature rod connection block and a first high-temperature resistant connection rod (6), a high-temperature resistant conversion head and a high-temperature resistant bolt upper connection body (11) which are connected in sequence, one end of the first conversion connection stud (2) is threadedly connected to one end of the first water-cooling connection head (3), the first water-cooling connection head (3) is provided with a first T-slot (4), and is connected to the T-rod end of the first high-temperature rod connection block through the first T-slot (4), the first high-temperature rod connection block is threadedly connected to one end of the first high-temperature resistant connection rod (6), and the first high-temperature resistant connection rod (6) is sleeved with a first heat insulation sleeve (7), the first high-temperature resistant connection rod (6) is connected to one end of the high-temperature resistant conversion head, and the other end of the high-temperature resistant conversion head is threadedly connected to the high-temperature resistant bolt upper connection body (11); The lower clamp comprises a second conversion connection stud, a second water-cooling connection head, a second high-temperature rod connection block, a second high-temperature resistant connection rod, and a high-temperature resistant bolt lower connection body (13) which are connected in sequence; One end of the second conversion connection stud is threadedly connected to one end of the second water-cooling connection head, the second water-cooling connection head is provided with a second T-slot, and is connected to the T-rod end of the second high-temperature rod connection block through the second T-slot, the second high-temperature rod connection block is threadedly connected to one end of the second high-temperature resistant connection rod, and the second high-temperature resistant connection rod is sleeved with a second heat-insulating sleeve, and the second high-temperature resistant connection rod is threadedly connected to the high-temperature resistant bolt lower connection body (13); The high temperature resistant bolt upper connector (11) is provided with a cavity with an opening on one side, and one end of the cavity is provided with a through hole for the bolt to be tested (12) to pass through. After the bolt to be tested (12) passes through the through hole, it is threadedly connected to one end of the high temperature resistant bolt lower connector (13).

2. A high temperature fatigue test device for metal bolts according to claim 1, characterized in that: The first conversion connection stud (2) and the second conversion connection stud are respectively connected to the first wedge-shaped conversion head (1) and the second wedge-shaped conversion head.

3. A high temperature fatigue test device for metal bolts according to claim 1, characterized in that: A cooling cavity is provided inside the first water-cooling connector (3), and the cooling cavity is connected to a water-cooling pipeline via two first water-cooling nozzles (5) provided on both sides.

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