A device and method for reducing eddy current signal of local stress relief heat treatment of elbow

Abstract

The present invention relates to a heat treatment device, in particular to a device for reducing eddy current signals of local stress relief heat treatment of elbows, comprising a track and a roller movably resting on the track, and also comprising: a bracket, two of which are symmetrically provided, and the roller is installed at the bottom of the bracket; a clamping device, which is installed on the bracket; a clamping seat, which is rotatably installed on the bottom plates of the clamping device and the bracket respectively, and is relatively arranged, and is used to clamp the tube legs of a U-shaped tube through the clamping device; wherein, when the tube legs of the U-shaped tube are deformed during heating, heat preservation and cooling, the bracket moves on the track, and the clamping seat moves and rotates with the tube legs. The device for reducing eddy current signals of local stress relief heat treatment of elbows can effectively reduce the amplitude of the discontinuous process signal of the internal eddy current signal appearing at the clamping position after the stress relief heat treatment of the U-shaped tube, meet the high standard requirements of the U-shaped tube, and is easy to operate.

Description

Technical Field

[0001] The invention relates to a heat treatment device, in particular to a device and a method for reducing eddy current signals of local stress relief heat treatment of elbows. Background Art

[0002] U-shaped tubes used in the nuclear field have very high safety and reliability requirements due to their special use environment and long service life requirements. The current means of monitoring in-service pipes mainly rely on eddy currents inside U-shaped tubes, so the process signals monitored by the internal eddy currents are very high and need to be kept at a low amplitude.

[0003] At present, the local stress relief heat treatment of U-shaped tube elbows is achieved by electrode clamping electric heating. The elbow part of the U-shaped tube will deform during the heating process: the radius increases during heating, driving the tube legs to swing outward, and the radius decreases during cooling, and the tube legs are retracted. This deformation is determined by the physical properties of the material and cannot be avoided. In order to prevent the U-shaped tube from deforming during the heating process, the conventional heating equipment clamping mechanism adopts a fixed form. After adjusting the distance between the tube legs according to the incoming material, it will be stable and will not move. This method meets the requirements of products without internal eddy current detection, but it cannot meet the requirements for U-shaped tubes with high requirements for internal eddy current signals. This mandatory constraint will have a significant impact on the detection results of the U-shaped tube, and abnormal signals will appear in the internal eddy current detection, which cannot meet the requirements. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a device that can effectively reduce the amplitude of the discontinuous process signal of the internal eddy current signal appearing at the clamping position after the stress relief heat treatment of the U-shaped tube, and meet the high standard requirements of a U-shaped tube to reduce the eddy current signal of the local stress relief heat treatment of the elbow. The specific technical solution is:

[0005] A device for reducing eddy current signals of local stress relief heat treatment of elbows, comprising a track and a roller that moves against the track, and also comprising: a bracket, two of which are symmetrically provided, and the roller is installed at the bottom of the bracket; a clamping device, which is installed on the bracket; a clamping seat, which is rotatably installed on the clamping device and the bottom plate of the bracket respectively, and is arranged relatively to each other, and is used to clamp the tube legs of a U-shaped tube through the clamping device; wherein, when the tube legs of the U-shaped tube are deformed during heating, heat preservation and cooling, the bracket moves on the track, and the clamping seat moves and rotates with the tube legs.

[0006] Preferably, the clamping device comprises: a cylinder, the cylinder is fixed on the bracket, and the clamping seat is rotatably mounted on the piston rod of the cylinder.

[0007] Preferably, the clamping seat includes: a bearing seat, which is mounted on the clamping device and the base plate; an insulating block, which is rotatably mounted on the bearing seat; and an electrode clamp block, which is mounted on the insulating block, and the electrode clamp block is provided with a clamping groove for clamping the tube leg.

[0008] Furthermore, the electrode clamp is a silver clamp.

[0009] Preferably, there is a clearance fit between the clamping groove and the tube leg.

[0010] A method for reducing eddy current signals during local stress relief heat treatment of elbows, used for the above-mentioned device for reducing eddy current signals during local stress relief heat treatment of elbows. When a U-shaped tube is subjected to local stress relief heat treatment, the clamping seat is clamped on the tube leg and rotates and moves following the deformation of the tube leg, and the tube leg deforms in a horizontal plane.

[0011] Preferably, the pressure of the clamping seat clamping the tube leg makes the tube leg and the electrode clamp block fit effectively, and the amplitude of the internal eddy current process signal is proportional to the pressure.

[0012] Preferably, when the clamping seat clamps the tube leg, the clamping seat partially clamps the tube leg, and the tube leg can freely extend and retract on the clamping seat.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The device for reducing eddy current signals of local stress relief heat treatment of elbows provided by the present invention can effectively reduce the amplitude of the discontinuous process signal of the internal eddy current signal appearing at the clamping position after the stress relief heat treatment of the U-shaped tube, meet the high standard requirements of the U-shaped tube, and is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a structural schematic diagram of embodiment 1;

[0016] Figure 2 It is a schematic diagram of the deformation of the U-shaped tube;

[0017] Figure 3 It is a schematic diagram of the deformation decomposition of the U-shaped tube;

[0018] Figure 4 It is an internal eddy current detection pattern of an electrically heated U-shaped tube using a fixed clamping mechanism;

[0019] Figure 5 The inner eddy current detection pattern of the electrically heated U-shaped tube of the first embodiment is adopted; DETAILED DESCRIPTION

[0020] The present invention will be further described with reference to the accompanying drawings.

[0021] Embodiment 1

[0022] like Figures 1 to 3 As shown, a device for reducing eddy current signals of local stress relief heat treatment of elbows includes a track 43, a roller 42, a bracket 1, a clamping device 2, and a clamping seat 3. The track 43 is installed on the ground and is provided in plurality. The bracket 1 is L-shaped and symmetrically provided with two. Four or more rollers 42 are installed at the bottom of the bottom plate 11 of the bracket 1. The rollers 42 are movably supported on the track 43 and roll along the track 43. The clamping device 2 includes a cylinder, which is fixed to the top of the bracket 1 and is vertically arranged. The clamping seat 3 is rotatably installed on the clamping device 2 and the bottom plate 11, and is relatively arranged to clamp the tube legs of the U-shaped tube through the clamping device 2. Specifically, the clamping seat 3 includes a bearing seat 33, an insulating block 31 and an electrode clamping block 32. The bearing seat 33 is installed on the piston rod end of the cylinder and the bottom plate 11. The insulating block 31 is made of insulating material. The insulating block 31 is installed on the bearing seat 33 through an axis, and the insulating block 31 can rotate freely. The electrode clamp block 32 is mounted on the insulating block 31. The electrode clamp block 32 is provided with a clamping groove for clamping the tube leg. The clamping groove is an arc groove. There is a clearance fit between the clamping groove and the tube leg, so that the tube leg can be freely extended and retracted. The electrode clamp block 32 is a silver clamp block. When the tube leg of the U-shaped tube is deformed during the heating, heat preservation and cooling process, the bracket 1 moves on the track 43.

[0023] The friction between the roller 42 and the track 43 is small, so that when the tube leg is deformed, the bracket 1, the clamping device 2 and the clamping seat 3 can move freely with the tube leg. The roller 42 makes the bracket 1 form a sliding trolley.

[0024] When the U-shaped tube is subjected to local stress relief heat treatment, the elbow part will deform: when heated, the radius increases, and the tube legs move outward; when cooled, the radius decreases, and the tube legs retract. During the entire heat treatment process, the position of the tube legs changes, such as Figure 3 As shown, the clamping position undergoes a horizontal lateral displacement distance L and a rotation angle α, and the values ​​of L and α vary depending on the characteristics of the U-shaped tube itself and the bending radius.

[0025] Before the heat treatment begins, the bracket 1 is moved on the track 43 to a position corresponding to the bending radius of the U-shaped tube. During the local stress relief heat treatment, the clamping seat 3 follows the tube leg to complete the follow-up lateral movement change of the L distance and the follow-up rotation change of the α angle. The device for reducing the eddy current signal of the local stress relief heat treatment of the elbow can realize the horizontal rotation at any angle and the horizontal lateral movement, and rotate and move following the deformation of the tube leg during the local stress relief heat treatment.

[0026] When clamping the tube legs, adjust the pressure of the cylinder. Under the premise of ensuring that the tube legs and the electrode clamp 32 are effectively fitted, the amplitude of the internal eddy current process signal is proportional to the pressure, but it cannot be lower than the lower limit value that ensures that the tube legs and the electrode clamp 32 are fully fitted. Too low pressure will cause an arc between the electrode and the tube legs, making the U-shaped tube scrapped.

[0027] The electrode clamp 32 is in direct contact with the tube leg. Considering its conductivity and material hardness, silver is preferred. The clamping groove needs to be expanded and ground. The size of the clamping groove is slightly larger than the outer diameter of the tube to be heat treated, and the tube leg is not in a completely enclosed state at the clamping position, so that there is a certain amount of room for movement when the tube leg expands and contracts during the heat treatment process.

[0028] like Figures 1 to 3 As shown, taking a U-shaped tube with a diameter of 15 mm and a wall thickness of 1.2 mm as an example, first adjust the pressure of the cylinder to 0.08 MPa, and the diameter of the clamping groove of the electrode clamp 32 is 16 mm; then adjust the bracket 1 to the corresponding position along the track 43 according to the bending radius of the U-shaped tube to be stress-relieved; place the two tube legs of the U-shaped tube in the clamping grooves of the electrode clamp 32 located on the bottom plate 11 respectively; start the cylinder, so that the electrode clamp 32 on the cylinder is pressed down onto the electrode clamp 32 on the bottom plate 11, and the upper and lower electrode clamps 32 clamp the tube legs of the U-shaped tube; then perform elbow stress relief heat treatment on the U-shaped tube, and the heat treatment includes heating, heat preservation, and cooling.

[0029] like Figure 2 and Figure 3 As shown, during the entire heat treatment process, the clamping device 2 and the clamping seat 3 follow the tube legs to complete the follow-up lateral movement change of the L distance and the follow-up rotation change of the α angle. During the heating, heat preservation and cooling process of the U-shaped tube, the clamping device 2 and the clamping seat 3 automatically rotate and translate along the motion trajectory of the clamping part of the tube legs to release the potential energy generated by the deformation of the steel tube, ensure the stable clamping of the steel tube, and effectively reduce the process signal amplitude of the discontinuous internal eddy current signal at the electrode clamping position after the U-shaped tube undergoes stress relief heat treatment.

[0030] like Figure 4 As shown in the figure, the U-shaped tube is fixed with the currently commonly used fixed clamping mechanism for local stress relief heat treatment of the elbow, that is, when the left and right clamping devices are adjusted according to the radius of the U-shaped tube, the tube is clamped, and the left and right clamping devices are fixed in the subsequent entire heat treatment process. In this way, the internal eddy current test is carried out after the stress relief heat treatment, and the test parameters are set as follows: the peak-to-peak value of the through hole ￠1.32mm of the comparison pattern is set to 8V at the main detection frequency of 380kHz. The collected signal curve is shown in Figure 4 As shown, the amplitude of the process signal is 1.41V, which is too large to meet the high standards of the U-shaped tube.

[0031] like Figure 5 As shown, the device for reducing eddy current signals of local stress relief heat treatment of elbows of this embodiment is used to perform local stress relief heat treatment of U-shaped pipe elbows. After the heat treatment, the same inspection parameter setting standard is used to perform internal eddy current detection on the U-shaped pipe. The collected signal curve is as shown in FIG. Figure 5 As shown, the process signal amplitude is 0.25V, and the amplitude is significantly reduced, meeting the high standard requirements of the U-shaped tube.

[0032] Embodiment 2

[0033] A method for reducing eddy current signals of local stress relief heat treatment of elbows, used for a device for reducing eddy current signals of local stress relief heat treatment of elbows, when a U-shaped tube is subjected to local stress relief heat treatment, a clamping seat 3 is clamped on the tube leg, and rotates and moves with the deformation of the tube leg, and the tube leg deforms in a horizontal plane. The pressure of the clamping seat 3 clamping the tube leg makes the tube leg and the electrode clamp block 32 fit effectively, and the amplitude of the internal eddy current process signal is proportional to the pressure. When the clamping seat 3 clamps the tube leg, the clamping seat 3 partially clamps the tube leg, and the tube leg can freely expand and contract on the clamping seat 3.

[0034] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the protection scope of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the protection scope of the claims of the present invention.

Claims

1. A device for reducing eddy current signals of local stress relief heat treatment of elbows, comprising a track (43) and a roller (42) movably abutting against the track (43), characterized in that: Also includes: A bracket (1), wherein two brackets (1) are symmetrically provided, and the roller (42) is mounted at the bottom of the bracket (1); A clamping device (2), the clamping device (2) being mounted on the bracket (1); A clamping seat (3), the clamping seat (3) being rotatably mounted on the clamping device (2) and the bottom plate (11) of the bracket (1), and being arranged opposite to each other, and being used for clamping the tube legs of the U-shaped tube through the clamping device (2); Wherein, when the tube legs of the U-shaped tube are deformed during the heating, heat preservation and cooling processes, the bracket (1) moves on the track (43), and the clamping seat (3) moves and rotates following the tube legs; The clamping seat (3) comprises: A bearing seat (33), the bearing seat (33) being mounted on the clamping device (2) and the base plate (11); an insulating block (31), the insulating block (31) being rotatably mounted on the bearing seat (33); and An electrode clamping block (32), the electrode clamping block (32) being mounted on the insulating block (31), the electrode clamping block (32) being provided with a clamping groove for clamping the tube leg; The electrode clamp (32) is a silver clamp; There is a clearance fit between the clamping groove and the tube leg, so that the tube leg can be freely extended and retracted on the clamping seat (3).

2. The device for reducing eddy current signal of local stress relief heat treatment of elbow according to claim 1, characterized in that: The clamping device (2) comprises a cylinder, the cylinder is fixed on the bracket (1), and the clamping seat (3) is rotatably mounted on the piston rod of the cylinder.

3. A method for reducing eddy current signals of local stress relief heat treatment of elbows, using the device for reducing eddy current signals of local stress relief heat treatment of elbows as claimed in claim 1, characterized in that: When the U-shaped tube is subjected to local stress relief heat treatment, the clamping seat (3) is clamped on the tube leg and rotates and moves following the deformation of the tube leg, and the tube leg deforms in a horizontal plane; The pressure of the clamping seat (3) clamping the tube leg causes the tube leg to effectively fit with the electrode clamp (32), and the amplitude of the internal eddy current process signal is proportional to the pressure and is not lower than the lower limit value of the complete fit between the tube leg and the electrode clamp (32); When the clamping seat (3) clamps the tube leg, the clamping seat (3) partially clamps the tube leg, and the tube leg can freely extend and retract on the clamping seat (3).

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