Device and method for adjusting rigid bulge height of nuclear fuel assembly grillwork strip

Abstract

The invention relates to a device and method for adjusting the height of a rigid protrusion of a nuclear fuel assembly grillwork strip. The device comprises a height reducing male die punch, a height reducing female die punch, an upper die frame, a height increasing male die punch, a height increasing female die punch and a lower die base. The height reducing male die punch and the height increasing male die punch are embedded in the inner side of the upper die frame in a module mode. The height reduction female die punch is embedded in the position, right opposite to the height reduction male die punch, of the inner side of the lower die base in a module mode. The heightening female die punch is embedded in the position, right opposite to the heightening male die punch, of the inner side of the lower die base in a module mode. By designing the device for synchronously and reversely adjusting the heights of the rigid protrusions on the same side of the strip, the technical problems that when a nuclear fuel assembly grillwork G factor is unqualified, the efficiency of the processes of rigid protrusion height adjustment, measurement judgment, readjustment and the like in the grillwork is low, and batch production is not facilitated are solved, and meanwhile the problem that after the strip rigid protrusion height is adjusted, the production efficiency is low is solved. The appearance, the size, the crack and the like of the rigid bulge are inconvenient to detect.

Description

Technical Field

[0001] This application belongs to the field of nuclear fuel assembly manufacturing technology, specifically relating to a device and method for adjusting the height of the rigid protrusions of the grid strips in a nuclear fuel assembly. Background Technology

[0002] The nuclear fuel assembly grid is a crucial component of nuclear power fuel assemblies, playing a critical role in their normal and safe operation. The grid is assembled and welded from multiple strips. The grid cell dimensions are extremely important for the clamping effect on the fuel rods. To ensure the grid performance meets all design technical requirements, the G-factor measurement and calculation results must meet design requirements during the testing of grid dimensions and other indicators. Whether the G-factor is qualified or not is mainly determined by the height difference between the upper and lower rigid protrusions of the same strip within the grid cell. If the grid G-factor is unqualified, the height of the rigid protrusions needs to be manually adjusted to achieve the required G-factor. The adjustment process involves determining whether to lower or raise the height of the rigid protrusion based on measurement results, and then using appropriate tools for adjustment. After adjustment, measurements and judgments are performed again until the G-factor is qualified. This method is time-consuming and inefficient when there are significant height differences among the many grid cells, failing to meet the requirements for efficient mass production of grids.

[0003] Currently, grid strips are stamped using progressive dies. Due to the numerous structural features of grid strips, the stamping dies are relatively complex, and the stamping process involves many steps. Die adjustment is mainly based on the thickness and uniformity of the strip material to ensure that a series of indicators, such as the stamped rigidity height, meet the requirements. In mass production, due to factors such as poor strip thickness consistency, die wear, poor die machining accuracy or die deformation, and fluctuations in press accuracy, the stamped strip rigidity height fluctuates significantly. This is especially true when there is a large height difference between the same grid cells (upper and lower rigidities on the same side). Although the rigidity height value meets the design requirements, the large height difference will affect the pass rate of the G-factor, resulting in a low grid pass rate. If the die is constantly adjusted to address changes in strip thickness, the adjustment time is long (the main process consists of die removal, die disassembly, punch adjustment, die assembly, and die testing, sometimes requiring repeated adjustments), and the stability of the stamping process is also difficult to control. Generally, mold adjustment is performed based on the strip thickness to ensure that the vast majority of strips are qualified. For a small number of strips with large deviations in rigidity height but still meeting the design requirements, mold adjustment is not performed. This requires adjusting the rigidity height after the grid is assembled, which has the problems of low efficiency and difficulty in fully and effectively controlling the rigidity height. Summary of the Invention

[0004] In view of this, this application provides an apparatus and method for adjusting the height of the rigid protrusions of strips in a nuclear fuel assembly grid. By designing an apparatus for simultaneously and in reverse (or stepwise) adjusting the height of the rigid protrusions on the same side (upper and lower) of the strips, this invention solves the technical problem of low efficiency in the process of adjusting, measuring, judging, and readjusting the height of the rigid protrusions in the grid when the G-factor of the nuclear fuel assembly grid is unqualified, which is not conducive to mass production. It also solves the technical problem that it is not convenient to inspect the appearance, size, cracks, etc. of the rigid protrusions after the height of the strips is adjusted.

[0005] This application provides a device for adjusting the height of the rigid protrusions of nuclear fuel assembly grid strips. The device includes a height-reducing punch, a height-reducing die punch, an upper die holder, a height-increasing punch, a height-increasing die punch, and a lower die holder. The height-reducing punch and the height-increasing punch are modularly embedded inside the upper die holder. The height-reducing die punch is modularly embedded inside the lower die holder, directly opposite the height-reducing punch. The height-increasing die punch is modularly embedded inside the lower die holder, directly opposite the height-increasing punch. The protrusion height of the height-increasing punch is greater than that of the height-reducing punch. The groove depth of the height-reducing die punch is less than the groove depth of the height-increasing die punch.

[0006] In one specific embodiment of this application, a groove is provided at the middle position inside the upper mold frame or lower mold base, and the groove is used to place the strip spring during adjustment.

[0007] In one specific embodiment of this application, the device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips further includes a punch connecting handle, which is located outside the upper die frame and is used to mate with a pressure application device.

[0008] In one specific embodiment of this application, the device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips further includes a die connecting handle. The die connecting handle is disposed on the outside of the lower die holder.

[0009] In one specific embodiment of this application, the apparatus for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips further includes a loading and unloading device. The loading and unloading device is used to automatically place the strips into the corresponding positions based on the detection results.

[0010] In one specific embodiment of this application, the overall shape of the upper mold frame and the lower mold base combined is a cuboid.

[0011] A second aspect of this application provides a method for adjusting the height of the rigid protrusions of nuclear fuel assembly grid strips. This method is performed using the apparatus for adjusting the height of the rigid protrusions of nuclear fuel assembly grid strips as described in the first aspect of this application. The method includes: Step 1: Select the appropriate device to adjust the height of the rigidity of the nuclear fuel assembly grid strips based on the characteristics of the strip rigidity. Step 2: Place the strip to be adjusted onto the device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips, and confirm that the rigid protrusions to be adjusted and the device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips are in place. That is, the lower rigid protrusions are placed on the height-increasing die punch, and the higher rigid protrusions are placed on the height-reducing die punch; Step 3: Adjust the height of the first set of strip convex bulges by stamping. Step 4: After stamping is completed, remove the strip; Step 5: After adjustment, measure the height difference of the strip rigidity and the microcrack. If the measurement is qualified, adjust the rigidity of the next set of strips. If it is not qualified, increase or decrease the height of the punch and perform the stamping test again until the height difference of the rigidity meets the requirements.

[0012] In one specific embodiment of this application, the method for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips further includes: Step 6: After completing the adjustment of the first set of strip rigid protrusions, fix the mold and determine the process parameters; Step 7: Move to the next set of strip convex sections for stamping adjustment; Step 8: Perform adjustment result measurement.

[0013] The beneficial effects of this technical solution are as follows: By setting height-reducing punches and height-increasing punches in a modular form and embedding them on the upper die holder, and height-increasing die punches and height-reducing die punches in a modular form and embedding them on the lower die holder, the device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips has the function of synchronously and in reverse adjusting the height of the two rigid protrusions of the same grid element (i.e., the higher rigid protrusion decreases in height, and the lower rigid protrusion increases in height). The adjustment range of the rigid protrusion height of each strip is small, reducing the possibility of cracks caused by adjustment. Due to the simultaneous adjustment method, the adjustment efficiency is high, and the consistency of the rigid protrusion height after adjustment is good. At the same time, the device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips is easy to replace and adjust, and its simple structure makes it easy to implement adjustment. In addition, the device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips is suitable for effective adjustment of the rigid protrusion height of the strips in various situations. Attached Figure Description

[0014] Figure 1 The diagram shown is a schematic of a rigid convex strip.

[0015] Figure 2 The diagram shown is a schematic of a strip spring.

[0016] Figure 3 The diagram shown is a structural schematic of a device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips according to an embodiment of this application. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. It should be noted that there are many types of grid strips, and there are generally three types with rigid protrusions, such as... Figure 1 Two types of strip rigid convex 1-1 and Figure 2 Middle strip spring 1-2.

[0018] At least one embodiment of this application provides a device for adjusting the height of the rigid protrusions of the grid strips in a nuclear fuel assembly, see reference. Figure 3 The device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips includes a height-reducing punch 2-2, a height-reducing die punch 2-3, an upper die holder 2-5, a height-increasing punch 2-6, a height-increasing die punch 2-7, and a lower die holder 2-8. The height-reducing punch 2-2 and the height-increasing punch 2-6 are modularly embedded inside the upper die holder 2-5. The height-reducing die punch 2-3 is modularly embedded inside the lower die holder 2-8, directly opposite the height-reducing punch 2-2. The height-increasing die punch 2-7 is modularly embedded inside the lower die holder 2-8, directly opposite the height-increasing punch 2-6. The protrusion height of the height-increasing punch 2-6 is greater than that of the height-reducing punch 2-2. The groove depth of the height-reducing die punch 2-3 is less than the groove depth of the height-increasing die punch 2-7.

[0019] It should be noted that the upper die holder 2-5 and the lower die base 2-8 together constitute the die holder. The reducing punch 2-2 and the increasing punch 2-6 together constitute a double rigid punch adjusting die punch; both the reducing punch 2-2 and the increasing punch 2-6 are punches. The reducing die 2-3 and the increasing die 2-7 together constitute a double rigid punch adjusting die punch; both the reducing die 2-3 and the increasing die 2-7 are dies. The dimensions of the reducing punch 2-2, the increasing punch 2-6, the reducing die 2-3, and the increasing die 2-7 can be matched or replaced according to the dimensions of the rigid punch to be adjusted.

[0020] In this embodiment, by modularly embedding a height-reducing punch 2-2 and a height-increasing punch 2-6 onto the upper die holder 2-5, and modularly embedding a height-increasing die punch 2-7 and a height-reducing die punch 2-3 onto the lower die holder 2-8, the device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips has the function of synchronously and in reverse adjusting the two rigid protrusions of the same grid element (i.e., the higher rigid protrusion decreases in height, and the lower rigid protrusion increases in height). The adjustment range of the rigid protrusion height of each strip is small, reducing the possibility of cracks caused by adjustment. Due to the simultaneous adjustment method, the adjustment efficiency is high, and the consistency of the rigid protrusion height after adjustment is good. At the same time, the device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips is easy to replace and adjust, and its simple structure makes it easy to implement adjustment. In addition, the device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips is suitable for effective adjustment of the rigid protrusion height of strips in various situations.

[0021] In at least one embodiment of this application, a groove is provided at the middle position of the inner side of the upper mold holder 2-5 or the lower mold base 2-8, and the groove is used to place the strip spring during adjustment.

[0022] In at least one embodiment of this application, the device for adjusting the height of the rigid protrusion of the nuclear fuel assembly grid strip further includes a punch connecting handle 2-1, which is located outside the upper mold frame 2-5 and is used to be fitted with a pressure application device.

[0023] In at least one embodiment of this application, the device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips further includes a die connecting handle 2-4. The die connecting handle 2-4 is disposed on the outside of the lower die holder 2-8.

[0024] It should be noted that the upper mold holder 2-5 and / or the lower mold base 2-8 can be installed in conjunction with equipment such as presses, or they can be installed in conjunction with manual pressure devices.

[0025] In at least one embodiment of this application, the apparatus for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips further includes a loading and unloading device. The loading and unloading device is used to automatically place the strips in the appropriate positions based on the detection results. This allows the apparatus for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips to achieve automated adjustment.

[0026] In at least one embodiment of this application, the overall shape of the upper mold frame 2-5 and the lower mold base 2-8 after combination is a cuboid.

[0027] When adjusting the height of the rigid protrusions of nuclear fuel assembly grid strips using the device described in the above embodiments of this application, the strips are placed into the corresponding concave molds according to the required rigid protrusion height. That is, strips requiring increased rigid protrusion height are placed in deeper concave molds, and strips requiring decreased rigid protrusion height are placed in shallower concave molds. If a rigid protrusion does not require adjustment, no punch or die is installed at that adjustment position. By applying pressure (e.g., 10 kg) to the upper and lower die frames, the punch is pressed into the concave mold and pressure is held if necessary (e.g., for 3 seconds). The adjustment is completed by lifting the punch. If the strip rigid protrusion adjustment device requires the installation of a strip clamping device, it can be designed and installed on the adjustment device according to requirements. This application embodiment does not make specific requirements.

[0028] It should be noted that high-precision stamping equipment (with a tonnage sufficient for rigid convex stamping, such as a 1-ton press) can be used to design and adjust the height of the rigid convex strips in the nuclear fuel assembly grid strips, according to the rigid convex structure and design dimensions of different strips. The device for adjusting the height of the rigid convex strips in the nuclear fuel assembly grid strips is a double-rigid-convex die. Each rigid convex adjustment die consists of a punch and a die, and the die dimensions are based on the basic design dimensions of the rigid convex height, undergoing high-precision machining. The machining accuracy of the stamping equipment is controlled at the micron level.

[0029] The apparatus and method for adjusting the height of rigid protrusions in nuclear fuel assembly grid strips provided in this application not only achieve the goal of reducing the height difference of rigid protrusions in the strips, but also facilitate the control of strip quality. Appropriate devices for adjusting the height of rigid protrusions in nuclear fuel assembly grid strips can be manufactured for different strip rigid protrusion structures. By replacing the device for adjusting the height of rigid protrusions in nuclear fuel assembly grid strips, fine adjustments can be made to the height of different strips. If one rigid protrusion is too high or too low, while another rigid protrusion is at the median (design value), only the rigid protrusion with the larger deviation is adjusted.

[0030] At least one embodiment of this application also provides a method for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips. This method is performed using an apparatus described in the above embodiments for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips. The method includes steps 1 to 5.

[0031] Step 1: Select the appropriate device to adjust the height of the rigidity of the nuclear fuel assembly grid strips based on the rigidity characteristics of the strips.

[0032] For example, the rigid convex height (design value 1.448 (+0.032, -0.033) mm), the deviation value of the rigid convex height of the stamped strip is 0.02 mm. The selection of the rigid convex height adjustment die is as follows: the depth of the die cavity of the height-increasing die is 1.448 (+0.015, 0) mm, and the height of the punch of the height-increasing die is 1.1813 (+0.015, 0) mm; the depth of the die cavity of the height-reducing die is 1.448 (0, -0.015) mm, and the height of the punch of the height-reducing die is 1.1813 (0, -0.015) mm.

[0033] Step 2: Place the strip to be adjusted onto the device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips, and confirm that the rigid protrusions to be adjusted and the device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips are in place. That is, the lower rigid protrusions are placed on the height-increasing die punch 2-7, and the higher rigid protrusions are placed on the height-reducing die punch 2-3.

[0034] It should be noted that the height-increasing die punches 2-7 are stamping stations with increased height. The height-reducing die punches 2-3 are stamping stations with decreased height.

[0035] In some embodiments, automatic loading is used: a loading and unloading device automatically places the strip into the corresponding position based on the detection results and designs the stamping parameters.

[0036] Step 3: Adjust the height of the first set of strip convex ...

[0037] For example, stamping can be done in two ways: with and without pressure. Without pressure, the die is removed after pressing. This test uses the pressure-holding method, with a holding time of 3 seconds after pressing. The stamping pressure can be determined based on the material strength of the strip's rigidity; for example, this test uses a pressure of 10 kg.

[0038] Step 4: After stamping is completed, remove the strip.

[0039] It should be noted that necessary safety measures were taken during the stamping process to ensure that the test met safety requirements.

[0040] Step 5: Measure the height difference of the adjusted strip's rigidity and the microcracks. If the measurements are satisfactory, proceed to the next set of strip rigidity adjustments. If unsatisfactory, increase or decrease the punch height and repeat the stamping test until the rigidity height difference meets the requirements.

[0041] In at least one embodiment of this application, the method for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips further includes steps 6 to 8.

[0042] Step 6: After completing the adjustment of the first set of strip rigid convexity, fix the mold and determine the process parameters.

[0043] For example, process parameters include pressure, holding time, etc.

[0044] Step 7: Move to the next set of strips for punching and adjustment.

[0045] Specifically, once the height of the convex section of the strip is adjusted, the next set of strips is placed.

[0046] Step 8: Perform adjustment result measurement.

[0047] It should be noted that once the process is stable, measurements are no longer required, and the adjustment of the rigidity of the next set of strips can be carried out directly.

[0048] The above embodiments of this application have the following beneficial effects: 1) By employing a bidirectional adjustment technique for the rigid convex height of the strip grid elements, precise control over the strip rigid convex height adjustment was achieved, improving the consistency of the adjusted rigid convex height and ensuring that the difference in rigid convex height on the same side of the strip is controlled to be no greater than 0.01 mm. With the strip rigid convex height difference controlled to no greater than 0.01 mm, experiments have demonstrated that the project significantly improves the pass rate of the grid G-factor.

[0049] 2) By employing a technique of bidirectional synchronous adjustment of the rigid convex height of the strip grid elements, effective inspection of the dimensions and appearance of the strip after adjustment is achieved, thus improving the reliability of the strip quality. Adjustments made within the grid elements are difficult to observe if deformation or micro-cracks occur in the strip rigid convexity, posing a risk of undetected defects.

[0050] 3) By using the adjustment device and method for the strip rigid punch, the effect of rapid and high-precision adjustment of strip batches is achieved, and the adjustment value can be effectively controlled (increasing the punch height, increasing the holding time, etc.), which facilitates the automation of adjustment.

[0051] 4) By using strip rigid convex height adjustment technology, the shaping effect of the contact surface of the rigid convex fuel rod is achieved, making its contact surface flatter.

[0052] It should be noted that the combination of the technical features in the embodiments of this application is not limited to the combination methods described in the embodiments of this application or the combination methods described in specific embodiments. All technical features described in this application can be freely combined or combined in any way, unless they contradict each other.

[0053] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the term "comprising" only indicates that it includes the explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0054] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A device for adjusting the height of the rigid protrusions in the grid strips of a nuclear fuel assembly, characterized in that, It includes a height-reducing punch, a height-reducing die punch, an upper die set, a height-increasing punch, a height-increasing die punch, and a lower die set. The height-reducing punch and the height-increasing punch are embedded in the inner side of the upper die set in a modular form. The height-reducing die punch is embedded in the inner side of the lower die set in a modular form, directly opposite the height-reducing punch. The height-increasing die punch is embedded in the inner side of the lower die set in a modular form, directly opposite the height-increasing punch. The protrusion height of the height-increasing punch is higher than that of the height-reducing punch, and the groove depth of the height-reducing die punch is less than that of the height-increasing die punch.

2. The device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips according to claim 1, characterized in that, A groove is provided in the middle of the inner side of the upper mold holder or lower mold base. The groove is used to place the strip spring during adjustment.

3. The device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips according to claim 1, characterized in that, It also includes a punch connecting handle, which is located outside the upper die frame and is used to mate with the pressure application device.

4. The device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips according to claim 1, characterized in that, It also includes a die connecting handle, wherein the die connecting handle is located on the outside of the lower die holder.

5. The device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips according to claim 1, characterized in that, It also includes a loading and unloading device, which is used to automatically place the strip into the corresponding position based on the test results.

6. A device for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips according to any one of claims 1 to 5, characterized in that, The overall shape of the upper mold frame and the lower mold base is a cuboid.

7. A method for adjusting the height of the rigid protrusions in the grid strips of a nuclear fuel assembly, characterized in that, include: Step 1: Select the appropriate device to adjust the height of the rigidity of the nuclear fuel assembly grid strips based on the characteristics of the strip rigidity. Step 2: Place the strip to be adjusted on the device for adjusting the height of the rigid protrusion of the nuclear fuel assembly grid strip, and confirm that the rigid protrusion to be adjusted and the device for adjusting the height of the rigid protrusion of the nuclear fuel assembly grid strip are in place, that is, the lower rigid protrusion is placed on the height-increasing die punch, and the higher rigid protrusion is placed on the height-reducing die punch. Step 3: Adjust the height of the first set of strip convex bulges by stamping. Step 4: After stamping is completed, remove the strip; Step 5: After adjustment, measure the height difference of the strip rigidity and the microcrack. If the measurement is qualified, adjust the rigidity of the next set of strips. If it is not qualified, increase or decrease the height of the punch and perform the stamping test again until the height difference of the rigidity meets the requirements.

8. The method for adjusting the height of the rigid protrusions of the nuclear fuel assembly grid strips according to claim 7, characterized in that, Following step 5, the following is also included: Step 6: After completing the adjustment of the first set of strip rigid protrusions, fix the mold and determine the process parameters; Step 7: Move to the next set of strip convex sections for stamping adjustment; Step 8: Perform adjustment result measurement.

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