High-temperature pull-off device for heat exchange tube and tube plate joint

Abstract

A high-temperature pull-off device for a heat exchange tube and a tube plate connector comprises an upper clamp threaded head and a center shaft which are of an integrated structure. The lower half part of the manual nut is matched and connected with the external thread connected with the clamp main body; the upper half part of the manual nut is in threaded connection with the upper end of the central shaft or the lower part of the upper clamp thread head; a flat key is arranged at the upper end of the center shaft and connected with a key groove in the corresponding position in the upper clamp body in a matched mode, the tail end of the center shaft is fixedly connected with a center shaft disc, and the center shaft disc is arranged in a jaw neck formed in the upper end of the locking jaw. The outer contour of the locking jaw is matched with the wedge shape of the inner cavity structure of the upper clamp body. Rotating handles are symmetrically and detachably mounted on the manual nut; the lower clamp thread head is installed on the lower end face of the lower clamp body, and the lower clamp body is provided with a cavity structure. The clamping device is firm and reliable in clamping, the tested high-temperature pulling-out force value is accurate, and the clamping device is suitable for all existing high-temperature tensile testing machines.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical property detection of metal materials, and in particular relates to a high-temperature pulling-off device for a joint of a heat exchange tube and a tube sheet. Background Art

[0002] The connection between the heat exchange tube and the tube sheet of the shell and tube heat exchanger often fails under high temperature and high pressure conditions, causing huge economic losses to the company and even threatening the life safety of the operators. At present, relevant scientific researchers have conducted a lot of research on the high-temperature pull-off performance of the heat exchange tube and tube sheet joints, mainly testing the high-temperature pull-off force. One method is to horizontally open a hole at one end of the heat exchange tube of the heat exchange tube and tube sheet joint, and then connect it to the high-temperature tensile testing machine with a pin shaft, completely place the heat exchange tube and tube sheet joint in the heating furnace of the high-temperature tensile testing machine for heating, and then conduct a pull-off test after insulation. This method has an accurate pull-off temperature, but the hole at one end of the heat exchange tube becomes the weakest part of the heat exchange tube. It often breaks at this part during the pull-off process, and no pull-off data can be obtained. Another method is to weld a plunger inside one end of the heat exchange tube of the heat exchange tube and tube sheet joint, heat the heat exchange tube and tube sheet joint to a specified temperature in a horse boiling furnace, and then clamp it on a universal testing machine. Use a downward force to press the heat exchange tube and tube sheet joint through the plunger welded inside one end of the heat exchange tube. This method cannot guarantee a certain temperature during the test. There are dangers in the transfer and clamping process of the high-temperature heat exchange tube and tube sheet joint, and there are also fractures in the welding plunger during the pressing process. Therefore, the high-temperature pull-off data obtained by this method is inaccurate. In addition, most of the current domestic relevant standards and specifications are room temperature pull-off force tests, or further conduct pull-off force test research by combining experiments and numerical simulations. Under high temperature conditions, there is no clear evaluation standard for the mechanical properties of tube head and tube sheet joints, and there is a lack of corresponding quality assurance technical specifications in China. Summary of the invention

[0003] The present invention provides a high-temperature pull-off device for a heat exchange tube and tube sheet joint, which has firm and reliable clamping, and the tested high-temperature pull-off force value is accurate, and can provide test data support for the formulation and revision of standards and technical specifications in this field.

[0004] The technical solution adopted by the present invention is: A high-temperature pulling-off device for a heat exchange tube and tube sheet joint, comprising an upper clamp threaded head located outside an upper clamp body and a central axis located inside the upper clamp body, the two being an integrated structure; the lower half of a manual nut is cooperatively connected with an external thread connected to the clamp body, the upper half of the manual nut is threadedly connected with the upper end of the central axis or with the lower part of the upper clamp threaded head; a flat key is provided at the upper end of the central axis, which cooperates with a keyway at a corresponding position in the upper clamp body, the end of the central axis is fixedly connected to a central axis disk, and the central axis disk is provided in a jaw neck opened at the upper end of a locking jaw; the outer contour of the locking jaw is wedge-shapedly adapted to the inner cavity structure of the upper clamp body; a rotating handle is symmetrically and detachably installed on the manual nut; the lower clamp threaded head is installed on the lower end surface of the lower clamp body, and the lower clamp body has a cavity structure.

[0005] The inner side of the locking jaws is an inclined surface, the bottom of the inclined surface is provided with a penetrating rectangular groove, and the inclined surface is provided with dotted sharp teeth.

[0006] The size of the widest part of the upper clamp body is no more than 100 mm.

[0007] The present invention places the clamping device and the joint of the heat exchange tube and the tube sheet completely in the heating furnace of the high-temperature tensile testing machine, and the clamping is firm and reliable, and the tested high-temperature pull-off force value is accurate. The most important thing is that the high-temperature pull-off clamping device is suitable for all existing high-temperature tensile testing machines, which can fill the technical gap of high-temperature pull-off force testing of tube heads and tube sheets of shell and tube heat exchangers in my country, and effectively consolidate the technical foundation for the development of shell and tube heat exchangers in China in the high-temperature field. In the entire industry, it will provide technical highlights for the development of high-temperature pull-off force inspection and testing, establish industry technical advantages, and provide test data support for the formulation and revision of standards and technical specifications in this field. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 is a cross-sectional view of the main body of the upper clamp of the present invention; Figure 3 It is a left view of the main body of the upper clamp of the present invention; Figure 4 This is a front view of the connection between the upper clamp body and the upper pull rod of the present invention; Figure 5 It is a bottom view of the locking jaws of the present invention clamping the heat exchange tube; Figure 6 It is a left side view of the locking jaws of the present invention. DETAILED DESCRIPTION

[0009] The present invention is further described below in conjunction with the accompanying drawings and implementation modes thereof.

[0010] Reference Figure 1-3, a high-temperature pulling-off device for a heat exchange tube and tube sheet joint, comprising an upper clamp threaded head 1 located outside the upper clamp body 3, and a central axis 11 located inside the upper clamp body 3, the two being an integrated structure; the lower half of a manual nut 12 is matched with the external thread connected to the clamp body, and the upper half of the manual nut 12 is threadedly connected to the upper end of the central axis 11 or is threadedly connected to the lower part of the upper clamp threaded head 1; a flat key is provided at the upper end of the central axis 11, which is matched with a keyway 19 at a corresponding position in the upper clamp body 3, and the end of the central axis 11 is fixedly connected to the central axis disk 10, which is arranged in the jaw neck 4 opened at the upper end of the locking jaw 5; the outer contour of the locking jaw 5 is adapted to the inner cavity structure of the upper clamp body 3; a rotating handle 2 is symmetrically and detachably installed on the manual nut 12; the lower clamp threaded head 9 is installed on the lower end surface of the lower clamp body 7, and the lower clamp body 7 has a cavity structure.

[0011] Turning the rotating handle 2 drives the upper clamp body 3 to move up and down, and then drives the central axis 11 to drive the central axis disc 10 to drive the locking jaw 5 to move up and down through the cooperation with the jaw neck 4. During the pulling-off process, the greater the downward pulling force applied, the greater the horizontal force applied by the wedge-shaped upper clamp body 3 to the heat exchange tube 6 through the locking jaw 5, and the heat exchange tube 6 is firmly locked inside the locking jaw 5.

[0012] Reference Figure 4 , Figure 5 The inner side of the locking jaw 5 is an inclined surface, the bottom of the inclined surface has a through rectangular groove 16, and the inclined surface is provided with point-mounted sharp teeth 18. This makes the heat exchange tube clamping more secure.

[0013] The widest part of the upper clamp is the upper clamp body 3, and the size of the widest part of the upper clamp body 3 is not greater than 100 mm. It is ensured that the device is applicable to all existing high-temperature tensile testing machines.

[0014] Working process of the present invention: (1) Clamping the sample: One end of the heat exchange tube 6 is interference fit with the plunger 17, and the end is placed in the locking jaws 5. The locking jaws 5 are locked to the heat exchange tube 6 by rotating the handle 2. The rotating handle 2 is unscrewed, and the upper clamp and the sample are connected to the pull rod 14 as a whole through the upper clamp thread head 1. The lower clamp is then connected to the lower pull rod through the lower clamp thread head 9. The tube sheet 8 is connected to the lower clamp through the inner cavity of the lower clamp body 7. Finally, the crossbeam position of the tensile testing machine is adjusted to return the lower pull rod to the initial tensile position.

[0015] (2) Heating: Place the upper fixture, the specimen and the lower fixture as a whole in the heating furnace of the high temperature tensile testing machine for heating, and set the temperature to 500°C.

[0016] (3) Sample pull-off: After keeping warm for 0.5 h, apply a displacement load at a rate of 3 mm / min. The maximum force generated is recorded as the pull-off force of the joint between the heat exchange tube and the tube sheet.

[0017] (4) Disassembly of the sample: After cooling to 300°C, open the heating furnace, connect the rotating handle 2 to the manual nut 12 through the internal thread 13, turn the rotating handle 2 to move the locking jaws 5 upward, and remove the pulled-off heat exchange tube 6.

Claims

1. A high temperature pull-off device for a heat exchange tube and tube sheet joint, characterized in that: The invention comprises an upper clamp threaded head (1) located outside the upper clamp body (3) and a central shaft (11) located inside the upper clamp body (3), the two being an integral structure; the lower half of a manual nut (12) is cooperatively connected with an external thread connected to the clamp body, and the upper half of the manual nut (12) is threadedly connected with the upper end of the central shaft (11) or with the lower half of the upper clamp threaded head (1); a flat key is provided at the upper end of the central shaft (11), and the flat key is connected with a key at a corresponding position in the upper clamp body (3). The groove (19) is matched and connected, the end of the central axis (11) is fixedly connected to the central axis disc (10), and the central axis disc (10) is arranged in the jaw neck (4) opened at the upper end of the locking jaw (5); the outer contour of the locking jaw (5) and the inner cavity structure of the upper clamp body (3) are wedge-shaped adapted; the manual nut (12) is symmetrically and detachably mounted with a rotating handle (2); the lower clamp threaded head (9) is mounted on the lower end surface of the lower clamp body (7), and the lower clamp body (7) has a cavity structure.

2. A high temperature pulling-off device for heat exchange tube and tube sheet joint according to claim 1, characterized in that: The inner side of the locking jaws (5) is an inclined surface, the bottom of which is provided with a rectangular groove (16) extending therethrough, and dotted sharp teeth (18) are arranged on the inclined surface.

3. A high temperature pulling-off device for heat exchange tube and tube sheet joint according to claim 1, characterized in that: The dimension of the widest part of the upper clamp body (3) is no greater than 100 mm.

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