Superconducting cavity half-cavity precision stamping device capable of automatic demolding and stamping method

Abstract

The application provides a precision stamping device and method for superconducting cavity half-cavity capable of automatic demolding, and relates to the technical field of superconducting cavity processing and manufacturing. The device completes high-purity niobium half-cavity drawing forming through the cooperation of a female die and a male die, controls the flow of the edge of the plate through a blank holder control plate, ensures the coaxiality of the movement of the upper and lower dies and the blank holder through guide columns and guide blocks, and controls the blank holding and demolding height through limiting screws. Meanwhile, a multi-stage ejection force transmission structure is formed by an ejector, a second ejector rod, a supporting plate, a first ejector rod and a blank holder, so that the concentrated ejection force is dispersed through the supporting plate and then transmitted to the blank holder, the smooth and automatic demolding of the half-cavity from the male die is realized, the workload of manual prying is reduced, and the processing efficiency is improved. Meanwhile, a three-stage gradient pressure maintaining strategy is adopted during stamping, which can reduce the rebound of the high-purity niobium half-cavity, improve the batch manufacturing efficiency, demolding stability and surface quality consistency of the superconducting cavity half-cavity.

Description

Technical Field

[0001] This invention relates to the field of superconducting cavity processing and manufacturing technology, and in particular to a precision stamping device and stamping method for superconducting cavity semi-cavities that can automatically demold. Background Technology

[0002] Radio frequency (RF) superconducting cavities are the core energy conversion components in particle accelerators. Their basic function is to establish a radio frequency electromagnetic field within the superconducting metallic cavity and accelerate particles through the interaction of this electromagnetic field with charged particles. Compared to room-temperature accelerator structures, RF superconducting cavities have advantages such as low RF loss, high energy utilization, and strong continuous wave operation capability. They are widely used in major scientific facilities such as synchrotron radiation sources, free-electron lasers, spallation neutron sources, high-current proton or heavy-ion accelerators, and high-energy physics colliders.

[0003] Currently, high-purity niobium is commonly used to manufacture superconducting cavities. High-purity niobium possesses excellent low-temperature superconducting properties, but its high material cost and stringent surface quality requirements make it susceptible to scratches, pressure marks, wrinkles, contamination, or localized deformation during stamping, drawing, handling, assembly, and subsequent welding, all of which can affect the final cavity performance. For superconducting cavities, the geometric accuracy, surface contour accuracy, coaxiality, wall thickness uniformity, and inner surface cleanliness of components directly influence the cavity's acceleration gradient, quality factor, and stable operation. Therefore, in the manufacturing process of superconducting cavities, stamping is not only the process for obtaining the basic shape of the parts but also a crucial preliminary process that determines subsequent machining, electron beam welding, and overall cavity performance.

[0004] Taking a 1.3 GHz 9-cell superconducting cavity as an example, it typically includes nine accelerator cells and two beam tube assemblies at both ends. Each accelerator cell consists of two half-cavity components, and a single 9-cell superconducting cavity requires multiple high-precision half-cavity components. These half-cavity components are mostly made from high-purity niobium plates through stamping and drawing, followed by machining, cleaning, and electron beam welding. With the increasing demand for superconducting cavities in large scientific facilities, the stamping efficiency, stability, and consistency of thin-walled, irregularly shaped curved surface components such as half-cavities and beam cups have become crucial aspects of the mass production of superconducting cavities.

[0005] The stamping of superconducting cavity components typically involves placing niobium plates or composite sheets in the positioning area of ​​a die or punch, fixing them with pressure plates, and then drawing or stamping them using a hydraulic press or oil press. Due to the complex curved surfaces, thin materials, and high surface quality requirements of superconducting cavity components, the stamping process requires strict control over the cleanliness of the die surface, lubrication, sheet positioning accuracy, pressure plate clamping, coaxiality of the die and punch, stamping force, holding time, and demolding method. Improper control of any of these aspects can easily lead to problems such as sheet misalignment, localized wrinkling, scratches, surface indentations, out-of-tolerance contours, uncontrolled springback, or difficulty in demolding, thus affecting subsequent machining allowances, welding and assembly accuracy, and overall cavity performance.

[0006] In existing technologies, the stamping forming of superconducting cavity half-cavities generally adopts conventional stamping processes. Conventional half-cavity stamping requires steps such as feeding, clamping the pressure plate, stamping, turning the die, releasing the pressure plate, flipping, demolding, and cleaning the mold. However, this process cannot automatically demold after stamping. The main reason is that the half-cavity experiences higher stress at the equator and iris, and the wall is thicker at the equator. After stamping, the half-cavity blank remains firmly inside the die and cannot automatically detach during the punch's return stroke. Manual flipping and demolding are necessary to remove the workpiece, which is cumbersome and labor-intensive. A single press can only stamp 12-15 half-cavities in an 8-hour workday, resulting in extremely low efficiency. Conventional stamping operations typically require four people working together, leading to high labor costs. Summary of the Invention

[0007] In view of this, and to address the above shortcomings, it is necessary to propose a precision stamping device and method for superconducting cavity semi-cavity that can automatically demold, thereby achieving automatic demolding after stamping, reducing labor costs, and improving processing efficiency.

[0008] This invention provides a precision stamping device for a superconducting cavity semi-cavity capable of automatic demolding, comprising: an upper base plate, a die pad, a die, a stripper plate, a lower pad, a first ejector pin, a second ejector pin, a support plate, a lower template, a punch seat, a punch, a blank holder ring, a guide post, and a guide block;

[0009] An ejector is fixedly installed at the lower center of the upper base plate, and the lower end of the ejector is fixedly connected to the ejector plate; the die pad is installed below the upper base plate, and a first through hole corresponding to the center of the die is opened in the center for the ejector plate to pass through; the die is fixedly installed below the die pad, and it has a forming cavity with a semi-bowl-shaped outer surface, and the ejector plate is located at the center of the forming cavity.

[0010] The lower pad has a second through hole at its center through which a second push rod passes. The upper end of the second push rod is fixed to the bottom of the support plate, and the lower end passes through the second through hole and connects to the auxiliary ejection cylinder of the lower working platform of the press. The upper end of the support plate is connected to the lower end of the first push rod, and the upper end of the first push rod passes through the lower template and the punch seat and contacts the pressure ring. The upper end of the support plate is fixedly connected to the lower template, and the lower end is fixedly connected to the lower pad. A guide post is fixedly installed at the edge of the lower template, and the upper end of the guide post slides with the upper base plate. The punch seat is fixed in the center of the lower template, and the punch is fixed on the upper end of the punch seat. The top end of the punch is adapted to the inner surface of the half-bowl. The pressure ring is installed on the outer periphery of the punch and can slide up and down along the outer wall of the punch. Its upper end is used to place the sheet metal to be punched. The lower end of the guide block is fixed on the lower template, and its inner side slides with the pressure ring. Limiting screws are also evenly distributed on the lower template to limit the highest position of the pressure ring sliding upward.

[0011] Preferably, the upper end of the ejector plate has a mounting recess for connecting with the ejector, and the lower end has a positioning recess that matches the shape of the top end of the punch.

[0012] Preferably, the punch is equipped with an embedded pressure sensor to monitor the die contact pressure during the stamping process.

[0013] Preferably, the lower template has guide post mounting holes at all four corners, with the guide posts installed at three corners and the other corner left empty.

[0014] Preferably, lifting rods are provided at the four corners of the upper base plate and the lower pad plate, and the surface of the lifting rods is provided with anti-slip knurling for the overall lifting of the mold.

[0015] Preferably, the limiting screws include four screws, which are evenly distributed around the punch; one end of each limiting screw is fixedly installed on the lower template, and the upper end extends out after passing through the pressure ring as a limiting end to limit the highest position of the pressure ring sliding upward.

[0016] Secondly, the present invention provides a precision stamping method for a superconducting cavity half-cavity capable of automatic demolding. This method is based on a precision stamping device for a superconducting cavity half-cavity capable of automatic demolding as described in any of the first aspects, and includes the following steps:

[0017] S1: Mold installation and cleaning;

[0018] S2: Stamping; The working platform on the press drives the upper base plate, die pad and die of the superconducting cavity semi-cavity precision stamping device that can automatically demold to move downwards. The relative movement of the punch presses the sheet material to be stamped into the forming cavity of the die.

[0019] S3: Graded pressure holding stress control; three-level gradient pressure holding after stamping, and determination of pressure holding end;

[0020] S4: Automatic demolding; After the pressure holding period ends, the working platform on the press returns, and the stamped half cavity is separated from the forming cavity of the die through the first-stage ejection, and the stamped half cavity is separated from the punch through the second-stage ejection.

[0021] S5: Workpiece removal and cleaning.

[0022] Preferably, the graded pressure-holding stress regulation in step S3 specifically includes:

[0023] S31: After the punch reaches the end point, it enters the first stage of pressure holding, and the pressure is maintained at the first pressure value for the first duration to force the sheet metal to be stamped to complete the plastic flow and fill the tiny parts of the mold forming cavity.

[0024] S32: After the first stage of pressure holding is completed, the pressure is linearly reduced to the second pressure value at the first preset rate, and the second stage of pressure holding begins; during the second stage of pressure holding, the pressure is maintained for the second duration to allow the internal stress of the sheet to redistribute and the elastic aftereffect to be gradually released;

[0025] S33: After the second stage of pressure holding is completed, the pressure is linearly reduced to the third pressure value at the second preset rate, and the third stage of pressure holding is entered; during the third stage of pressure holding, the pressure is maintained for the third duration so that the elasticity of the sheet tends to the elastic equilibrium state and the rebound trend is weakened.

[0026] S34: During the last fourth period of the third-stage pressure holding, determine whether the pressure fluctuation is not greater than the first preset pressure threshold and whether the change in the displacement sensor reading is not greater than the first preset displacement value; if so, determine that the current stress release is complete; otherwise, automatically extend the third-stage pressure holding time according to the preset extension rule.

[0027] Preferably, in step S31, the first pressure value is 120T±1T, and the first duration is 50~70 seconds;

[0028] In step S32, the second pressure value is 80T±1T, the second duration is 50~70 seconds, and the first preset rate is 4-6T / s;

[0029] In step S33, the third pressure value is 50T±1T, the third duration is 50~70 seconds, and the second preset rate is 4-6T / s;

[0030] In step S34, the fourth duration is 8 to 12 seconds, the first preset pressure threshold is 0.3-0.7T, and the first preset displacement value is 0.01-0.03mm.

[0031] Preferably, the first-stage ejection includes: after the pressure holding period ends, the press upper working platform returns, the upper base plate, the die pad, and the die move upward with the guide post; at the same time, the compression spring inside the ejector recovers its deformation, driving the ejector to eject the stamped half cavity from the die;

[0032] The secondary ejection includes: the second ejector rod receiving the ejection force and transmitting it to the support plate and the first ejector rod, pushing the pressure ring upward; the edge of the pressure ring pushes the bottom fold of the stamped half cavity, pushing the half bowl out of the punch.

[0033] As can be seen from the above technical solution, the precision stamping device and method for superconducting cavity semi-cavity with automatic demolding provided by the present invention completes the high-purity niobium semi-cavity drawing and forming through the cooperation of the die and punch. The blank holder controls the edge flow of the sheet metal, the guide pillars and guide blocks ensure the coaxiality of the upper and lower dies and the blank holder, and the limit screws control the blank holder and demolding height. Simultaneously, a multi-stage ejection force transmission structure is formed through the ejector, second ejector rod, support plate, first ejector rod, and blank holder, allowing the concentrated ejection force to be distributed through the support plate and transmitted to the blank holder, achieving smooth and automatic demolding of the semi-cavity from the punch, reducing the workload of manual prying and improving processing efficiency. It also reduces surface damage and contour deformation caused by manual prying. The method provided by this solution includes die installation and cleaning, stamping forming, graded pressure holding stress control, automatic demolding, and workpiece removal and cleaning. The graded pressure holding adopts a three-level gradient pressure holding strategy, which can reduce the springback of the high-purity niobium semi-cavity and improve contour accuracy. Simultaneously, after the pressure holding period ends, the press's upper working platform returns to its original position. As the die moves upward, the compression spring inside the ejector recovers its deformation and acts on the ejector plate, facilitating the separation of the half-cavity from the die and preventing the half-cavity from adhering to the die. Furthermore, the second ejector rod, the support plate, and the first ejector rod further push the pressure ring, enabling the half-cavity to detach from the punch. Thus, this solution can improve the batch manufacturing efficiency, demolding stability, and surface quality consistency of superconducting cavity half-cavities. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a superconducting cavity semi-cavity precision stamping device capable of automatic demolding, provided as an embodiment of the present invention.

[0035] Figure 2 for Figure 1 Sectional view at EE.

[0036] Figure 3 This is a schematic diagram of the lower die portion of a superconducting cavity semi-cavity precision stamping device capable of automatic demolding, provided as an embodiment of the present invention.

[0037] Figure 4 for Figure 3 Sectional view at point CC.

[0038] Figure 5This is a cross-sectional view of the upper die portion of a superconducting cavity semi-cavity precision stamping device capable of automatic demolding, provided as an embodiment of the present invention.

[0039] Figure 6 This is a schematic diagram of an upper base plate provided in an embodiment of the present invention.

[0040] Figure 7 This is a schematic diagram of a pressure ring provided in an embodiment of the present invention.

[0041] Figure 8 This is a schematic diagram of a lower template provided in an embodiment of the present invention.

[0042] Figure 9 This is a schematic diagram of the assembly of a punch and a punch holder provided in an embodiment of the present invention.

[0043] Figure 10 This is a schematic diagram of a concave mold pad provided in an embodiment of the present invention.

[0044] Figure 11 This is a schematic diagram of a die provided in an embodiment of the present invention.

[0045] Figure 12 This is a schematic diagram of a material ejection plate provided in an embodiment of the present invention.

[0046] In the figure: 1. Upper base plate, 2. Die backing plate, 3. Die, 4. Ejector plate, 5. Lower backing plate, 6. First ejector pin, 7. Second ejector pin, 8. Support plate, 9. Lower template, 10. Punch seat, 11. Punch, 12. Pressure ring, 13. Guide post, 14. Guide block, 15. Ejector, 16. Limit screw, 17. Lifting bar, 18. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0048] In the description of this invention, it should be noted that the terms "front," "rear," "inner," "outer," "right," "left," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0050] like Figure 1-12 As shown, the present invention provides a precision stamping device for a superconducting cavity semi-cavity capable of automatic demolding, comprising: an upper base plate 1, a die pad 2, a die 3, a stripper plate 4, a lower pad 5, a first ejector pin 6, a second ejector pin 7, a support plate 8, a support plate 9, a lower template 10, a punch seat 11, a punch 12, a pressure ring 13, a guide post 14, and a guide block 15;

[0051] An ejector 16 is fixedly installed at the lower center of the upper base plate 1, and the lower end of the ejector 16 is fixedly connected to the ejector plate 4; the die pad 2 is installed below the upper base plate 1, and a first through hole corresponding to the center of the die 3 is opened in the center for the ejector plate 4 to pass through; the die 3 is fixedly installed below the die pad 2, and it has a forming cavity with a semi-bowl-shaped outer surface, and the ejector plate 4 is located at the center of the forming cavity;

[0052] The lower pad 5 has a second through hole at its center through which the second push rod 7 passes. The upper end of the second push rod 7 is fixed to the bottom of the support plate 8, and the lower end passes through the second through hole and connects to the auxiliary ejection cylinder of the lower working platform of the press. The upper end of the support plate 8 is connected to the lower end of the first push rod 6. The upper end of the first push rod 6 passes through the lower template 10 and the punch seat 11 and contacts the pressure ring 13. The upper end of the support plate 9 is fixedly connected to the lower template 10, and the lower end is fixedly connected to the lower pad 5. A guide post 14 is fixedly installed at the edge of the lower template 10. The upper end is slidably engaged with the upper base plate 1; the punch seat 11 is fixed in the center of the lower template 10, the punch 12 is fixed on the upper end of the punch seat 11, and its top end shape is adapted to the inner surface of the half-bowl; the pressure ring 13 is installed on the outer periphery of the punch 12 and can slide up and down along the outer wall of the punch 12, and its upper end surface is used to place the sheet metal to be punched; the lower end of the guide block 15 is fixed on the lower template 10, and its inner side is slidably engaged with the pressure ring 13; the lower template 10 is also evenly distributed with limit screws 17 to limit the highest position of the pressure ring 13 sliding upward.

[0053] In this embodiment, the high-purity niobium semi-cavity drawing is completed by the cooperation of the die 3 and the punch 12. The flow of the sheet metal edge is controlled by the blank holder 13, and the coaxiality of the upper and lower dies and the blank holder 13 is ensured by the guide post 14 and the guide block 15. The blank holder and demolding height are controlled by the limit screw 17. At the same time, the ejector 16, the second ejector 7, the support plate 8, the first ejector 6 and the blank holder 13 form a multi-stage ejection force transmission structure, so that the concentrated ejection force is distributed by the support plate 8 and transmitted to the blank holder 13, realizing the smooth and automatic demolding of the semi-cavity from the punch 12, reducing the amount of manual prying and improving processing efficiency. It also reduces surface damage and contour deformation caused by manual prying.

[0054] The upper base plate 1 can be made of high-strength alloy steel, with a rectangular plate structure and guide post 14 mounting holes at the four corners for sliding engagement with the guide posts 14, totaling three guide posts 14. The top of the upper base plate 1 is fixedly connected to the working platform of the hydraulic press via T-slot bolts. The bottom surface of the upper base plate 1 has a die 3 mounting stop in the center, which is positioned and engaged with the die pad 2. The ejector 16 is fixedly installed at the center of the lower part of the upper base plate 1.

[0055] The die backing plate 2 is installed between the die 3 and the upper base plate 1 to evenly transmit the punching force and protect the upper base plate 1 from local indentation. The die backing plate 2 has a through hole in the center that corresponds to the center of the forming cavity on the die 3, so that the ejector 16 can pass through during demolding.

[0056] The die 3 is fixed below the die backing plate 2. The die 3 has a forming cavity in the center that matches the shape of the outer surface of the half-bowl, and the depth of the forming cavity is precisely machined according to the design value of the half-bowl. A stripper plate 4 is provided in the center of the forming cavity of the die 3 for ejecting the half-cavity from the die 3 during demolding.

[0057] The blank holder 13 is installed on the outer periphery of the punch 12 and can slide up and down along the outer wall of the punch 12. The lower end face of the blank holder 13 is an annular plane, used to press the edge of the sheet metal. A blank holder force adjustment mechanism is provided between the blank holder 13 and the die 3.

[0058] The ejector plate 4 is located inside the forming cavity of the die 3, and its shape matches the contour of the inner surface of the half-bowl. The ejector plate 4 also serves as a positioning hole for the material punch 12. Specifically, the upper center of the ejector plate 4 has a mounting recess that connects to the ejector 16, and the lower end has a positioning recess that matches the shape of the top of the punch 12. When the sheet metal is placed on top of the punch 12, the positioning recess on the ejector plate 4 cooperates with the punch 12 to achieve precise positioning of the center of the sheet metal, eliminating the need for a separate positioning block.

[0059] The punch 12 is fixed to the upper end of the punch holder 11. The top shape of the punch 12 is consistent with the inner surface of the half-bowl, and it is used for stamping. An embedded pressure sensor can be installed inside the punch 12 to monitor the die contact pressure in real time during the stamping process. The punch holder 11 is fixed in the center of the lower template 10, with the punch 12 installed at the upper end and the lower end connected to the ejection mechanism of the lower working platform of the press, that is, directly connected to the lower template 10.

[0060] The lower template 10 is a rectangular plate structure fixed to the lower working platform of the press. The lower template 10 has guide post 14 mounting holes at its four corners, with three corners having guide posts 14 installed and the remaining corner empty. This three-point configuration achieves complete positioning, avoids structural interference, and provides a more reasonable triangular distribution of central force. Furthermore, it simplifies processing, facilitates assembly and debugging, reduces frictional resistance, lowers the failure rate, and is more cost-effective. The guiding stability of the three guide posts 14 fully meets the requirements of the stamping process, while the four guide posts 14 offer no benefit and instead bring disadvantages such as jamming, deformation, and increased costs. More importantly, since loading and unloading positions are generally on the right side, having one less guide post during robotic loading and unloading facilitates robotic operation and prevents contact with materials. Furthermore, the lower template 10 has a punch seat 11 mounting stop in its center, and four limit screws 17 are evenly distributed on the upper surface of the lower template 10. The limiting screws 17 are evenly distributed around the punch 12. One end of each limiting screw 17 is fixedly installed on the lower template 10, and the upper end extends out after passing through the pressure ring 13 as a limiting end to limit the highest position of the pressure ring 13 sliding upward.

[0061] The support plate 9 is made of high-strength alloy steel. There are four pieces in total, symmetrically distributed diagonally, and installed between the lower template 10 and the lower pad plate 5 to support the support plate 8, the first top rod 6 and the second top rod 7.

[0062] There are four first ejector pins 6, symmetrically distributed diagonally. The lower end is fixed to the support plate 8, and the upper end passes through the lower template 10 and the punch seat 11 before contacting the pressure ring 13. The length of the first ejector pin 6 is designed to be replaceable according to the half-bowl depth. When replacing, there is no need to disassemble the entire mold; it can be pulled out from the bottom of the lower template 10.

[0063] The support plate 8 is located below the lower template 10, with its upper end connected to the first top rod 6 and its lower end connected to the second top rod 7. The support plate 8 is square and is used to transmit the top force.

[0064] The lower pad 5 is fixed below the support plate 9 and is used to control the lowest downward position of the limiting support plate 8. The lower pad 5 has a central hole through which the second push rod 7 passes.

[0065] There is one second push rod 7, located at the center of the device. Its upper end is fixed on the support plate 8, and its lower end is connected to the auxiliary push cylinder of the press's lower working platform. The second push rod 7 is used to receive the push force and transmit it to the support plate 8 and the first push rod 6.

[0066] There are eight lifting rods 18 in total, symmetrically installed at the four corners of the upper base plate 1 and the lower pad plate 5, for hoisting the mold as a whole. The lifting rods 18 are knurled for anti-slip purposes.

[0067] There are three guide pillars 14 in total. The lower ends are fixed to the triangles at the four corners of the lower template 10. The lower template 10 has mounting holes for the guide pillars 14 at three corners, leaving the other corner unmounted. The upper ends slide against the upper base plate 1. This three-guide-pillar design avoids over-positioning while ensuring guiding accuracy. A guiding accuracy compensation sleeve can be fitted onto each guide pillar 14. This compensation sleeve is a slotted conical sleeve with an inner hole that fits with the guide pillar 14 with a clearance, and an outer circle that fits with the conical surface of the guide sleeve hole in the upper base plate 1. After long-term use, tightening the adjusting nut at the end of the compensation sleeve allows it to contract radially, eliminating gaps caused by wear.

[0068] Four limiting screws 17 are evenly distributed and installed on the lower template 10, passing through the pressure ring 13, to limit the highest position of the pressure ring 13, i.e., the demolding height. The head of the limiting screw 17 contacts the limiting block above the pressure ring 13, and the closing height can be finely adjusted by rotating the limiting screw 17.

[0069] Two guide blocks 15 are installed between the lower template 10 and the die 3, and are located on both sides of the pressure ring 13. The lower end of the guide block 15 is fixed to the lower template 10, and its inner side slides in conjunction with the grooves opened on both sides of the pressure ring 13 to ensure the verticality of the pressure ring 13's vertical movement.

[0070] The ejector 16 is located at the center below the upper base plate 1 and is fixedly connected to the upper base plate 1. A compression spring is installed inside the ejector 16. During the stamping process, the press's working platform drives the upper base plate 1, the die pad 2, and the die 3 downwards. The punch 12 moves relative to the die, pressing the sheet metal into the cavity of the die 3. During this process, the ejector plate 4 is subjected to the reverse force of the compression spring inside the ejector 16, and the compression spring inside the ejector 16 is compressed and stores energy. After the pressure holding period ends, the press's working platform returns, and the die 3 moves upwards. The force of the compression spring inside the ejector 16 on the ejector plate 4 is released, and the compression spring inside the ejector 16 returns to its original deformation, driving the ejector 16 to eject the half-cavity from the die 3, thus separating the half-cavity from the die 3. The ejector 16 operates when the pressure holding period ends, the press's working platform returns, and the die 3 moves upward. The internal compression spring of the ejector 16 recovers its deformation and acts on the ejector plate 4, which facilitates the separation of the half-bowl from the die 3 and prevents the half-bowl from adhering to the die 3.

[0071] In one embodiment, the present invention also provides a precision stamping method for a superconducting cavity half-cavity capable of automatic demolding. This method is based on a precision stamping device for a superconducting cavity half-cavity capable of automatic demolding as described above, and includes the following steps:

[0072] S1: Mold installation and cleaning;

[0073] S2: Stamping; The working platform on the press drives the upper base plate 1, the die pad 2 and the die 3 of the superconducting cavity semi-cavity precision stamping device that can automatically demold to move downwards. The punch 12 moves relative to each other to press the sheet material to be stamped into the forming cavity of the die 3.

[0074] S3: Graded pressure holding stress control; three-level gradient pressure holding after stamping, and determination of pressure holding end;

[0075] S4: Automatic demolding; After the pressure holding period ends, the working platform on the press returns, and the stamped half cavity is ejected from the forming cavity of the die 3 through the first-stage ejection, and the stamped half cavity is ejected from the punch 12 through the second-stage ejection.

[0076] S5: Workpiece removal and cleaning.

[0077] The following provides a more detailed explanation of each of the above steps.

[0078] For step S1, mold installation and cleaning.

[0079] In this step, the mold installation and cleaning process involves personnel wearing clean nitrile gloves, observing the surface quality of the round material, and thoroughly cleaning the surfaces of the punch 12, die 3, and pressure plate with a lint-free cloth dampened with anhydrous ethanol to ensure there are no metal residues, foreign particles, or surface defects. Afterward, oil is applied, and the material is placed into the positioning hole of the punch 12 with the RF side facing down. After fixing, oil is applied to the upper surface (non-RF side) of the material (using a clean cloth), and a film is applied.

[0080] For step S2, stamping is performed.

[0081] In this step, the stamping process specifically involves the press working platform driving the upper base plate 1, the die pad 2, and the die 3 downwards, while the punch 12 moves relative to the plate and presses the sheet into the forming cavity of the die 3, thus achieving stamping.

[0082] For step S3, graded pressure holding stress control.

[0083] In this step, the graded pressure holding stress control can include the first stage of pressure holding, the second stage of pressure holding, the third stage of pressure holding, and the determination of the end of pressure holding. Specifically, it can include:

[0084] S31: After the punch 12 reaches the end point, it enters the first stage of pressure holding, and the pressure is maintained at the first pressure value for the first duration to force the sheet metal to be stamped to complete the plastic flow and fill the tiny parts of the mold forming cavity.

[0085] In this step, the first pressure value can be 120T±1T, and the first duration can be 60 seconds.

[0086] S32: After the first stage of pressure holding is completed, the pressure is linearly reduced to the second pressure value at the first preset rate, and the second stage of pressure holding begins; during the second stage of pressure holding, the pressure is maintained for a second duration so that the internal stress of the sheet material is redistributed and the elastic aftereffect is gradually released.

[0087] In this step, the second pressure value can be 80T±1T, the second duration can be 60 seconds, and the first preset rate can be 5 / s.

[0088] S33: After the second stage of pressure holding is completed, the pressure is linearly reduced to the third pressure value at the second preset rate, and the third stage of pressure holding is entered; during the third stage of pressure holding, the pressure is maintained for the third duration so that the elasticity of the sheet tends to the elastic equilibrium state and the rebound trend is weakened.

[0089] In this step, the third pressure value can be 50T±1T, the third duration can be 60 seconds, and the second preset rate can be 5T / s.

[0090] S34: During the last fourth period of the third-stage pressure holding, determine whether the pressure fluctuation is not greater than the first preset pressure threshold and whether the change in the displacement sensor reading is not greater than the first preset displacement value; if so, determine that the current stress release is complete; otherwise, automatically extend the third-stage pressure holding time according to the preset extension rule.

[0091] In this step, the pressure holding end judgment refers to the three-stage pressure holding for a total of 180 seconds. If the pressure fluctuation is ≤0.5T and the displacement sensor reading change is ≤0.02mm in the last 10 seconds, the stress release is judged to be complete; otherwise, the low pressure holding time will be automatically extended, such as by 10 seconds each time, with a maximum of 60 seconds.

[0092] For step S4, automatic demolding occurs.

[0093] In this step, after the automatic demolding and pressure holding are completed, the press's upper work platform returns, and the die 3 moves upward accordingly. This can include primary ejection and secondary ejection. Primary ejection solves the problem of die 3 adhering to the half-cavity, while secondary ejection solves the problem of punch 12 adhering to the half-cavity. Specifically, primary ejection and secondary ejection can include:

[0094] The first-stage ejection includes: after the pressure holding period ends, the press's upper working platform returns, and the upper base plate 1, die pad 2, and die 3 move upward with the guide post 14; simultaneously, the internal compression spring of the ejector 16 recovers its deformation, driving the ejector 16 to eject the stamped half-cavity from the die 3. At this time, the half-cavity is still fitted on the punch 12, and the ejector 16 returns to its initial state.

[0095] The secondary ejection includes: a second ejector rod 7 receiving the ejection force and transmitting it to the support plate 8 and the first ejector rod 6, pushing the pressure ring 13 upward; the edge of the pressure ring 13 pushes the bottom fold of the stamped half-cavity, pushing the half-bowl out of the punch 12. The limiting screw 17 limits the highest position of the pressure ring 13 upward, controlling the demolding height.

[0096] For step S5, the workpiece is removed and cleaned.

[0097] In this step, the workpiece removal and cleaning specifically involves the operator manually removing the half-cavity after demolding, cleaning the inner and outer surfaces with a lint-free cloth soaked in anhydrous ethanol, and immediately cleaning the mold to protect the stamping surface before returning it to its proper place. The equipment and work area are then cleaned, and tools are inventoried. The operator places the cleaned half-cavity into a special turnover box lined with soft material and labels it with the batch number.

[0098] The following detailed description of the solution is based on specific embodiments.

[0099] Taking a 1.3GHz 9-cell superconducting cavity high-purity niobium semi-cavity as an example, a circular high-purity niobium plate with an RRR value of not less than 300 is used, and stamping is performed using a 200T hydraulic stretching equipment and the superconducting cavity semi-cavity precision stamping device of the present invention, which can automatically demold.

[0100] First, clean the press worktable and surrounding floor, ensuring the worktable is free of debris and contaminants, and apply lubricating oil to the worktable surface. Then, insert the support rod into the worktable hole, retract the ejector device to the bottom dead center, and confirm that the support rod does not protrude above the worktable.

[0101] Before hoisting the mold, inspect it to ensure there are no protrusions, dents, cracks, oil stains, debris, or foreign particles. Then, hoist the mold onto the workbench, place leveling blocks, and lower the press slide at low speed for alignment. After confirming there is no interference, tighten the upper and lower mold bolts.

[0102] After the mold is installed, adjust the press to the adjustment mode and ejection mode, test the operation of the support rod and the ejection ring, and confirm that the support rod can be ejected and returned freely, and that the ejection ring can move up and return smoothly.

[0103] Before the formal stamping, clean the mold with anhydrous ethanol and a lint-free cloth, and cover the punch 12 with a clean shield when cleaning the die 3. After cleaning, apply niobium-specific stamping lubricant evenly to the outer surface of the punch 12, the inner surface of the die 3, the contact area of ​​the blank holder 13, and both sides of the round material.

[0104] The operator, wearing clean nitrile gloves, inspects the surface quality of the round high-purity niobium sheet and selects the side with better surface quality as the radio frequency (RF) facet. The RF facet is placed with the markings facing down, allowing the sheet to enter the annular positioning step. The correct orientation is confirmed using the anti-misalignment blocks. After positioning, lubricant is applied to the upper surface.

[0105] Set the press to semi-automatic stretching mode, set the ejector cylinder force to 5T, the main punching pressure to 120T, and the holding time to 180s. After pressing the row key, the pressure plate first pre-presses the edge of the round material, and then the punching punch 12 continues to move down and push the round material to be stamped and formed.

[0106] After the pressure holding is completed, the press upper working platform returns, the upper base plate 1, the die pad 2, and the die 3 move upward with the guide post 14, the compression spring inside the ejector 16 recovers its deformation, and drives the half cavity to be ejected from the die 3, so that the half cavity is separated from the die 3. At this time, the half cavity is still fitted on the punch 12.

[0107] The second ejector pin 7 receives the ejection force and transmits it to the support plate 8 and the first ejector pin 6, further pushing the pressure ring 13. The edge of the pressure ring 13 pushes the bottom of the half cavity, pushing the half cavity out of the punch 12. The limit screw 17 limits the highest position of the pressure ring 13, controls the demolding height, and makes the half cavity stably detach from the die 3 and stay at the part removal height.

[0108] The operator uses clean gloves or a vacuum suction tool to remove the semi-cavity, then cleans the inner and outer surfaces of the semi-cavity with anhydrous ethanol and a lint-free cloth, and performs a 100% visual inspection. Qualified parts are placed in a special packaging box lined with soft material and marked in the non-RF area. Defective parts are recorded with defect information and feedback is provided for process adjustments.

[0109] In summary, the precision stamping device and method for superconducting cavity semi-cavities with automatic demolding provided in this solution involves oriented the sheet metal with the radio frequency (RF) surface facing downwards, and coating the RF surface with a peelable protective film before stamping to prevent scratches. During the stamping process, a graded pressure-holding method is implemented to fully release the internal stress of the material. After stamping, the die 3 automatically ejects the semi-cavity under the action of the ejector 16, while a cleaning device performs spray cleaning and hot air drying on the inner and outer surfaces of the semi-cavity. Based on this solution, the peelable protective film on the RF surface reduces the scratch rate on the inner surface (RF surface) of the semi-cup from the conventional 3-5% to below 0.2%. Graded pressure holding reduces the batch consistency standard deviation of the semi-cavity contour, meeting design requirements without secondary shaping. Complete stamping parameters and contour detection data are recorded for each semi-cavity, facilitating quality traceability during subsequent electron beam welding and cavity performance analysis.

[0110] The modules or units in the device of this invention can be merged, divided, and deleted according to actual needs. The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that implementing all or part of the processes of the above embodiments and making equivalent changes according to the claims of this invention still fall within the scope of the invention.

Claims

1. A precision stamping device for a superconducting cavity semi-cavity capable of automatic demolding, characterized in that, include: Upper base plate, die pad, die, ejector plate, lower pad, first ejector pin, second ejector pin, support plate, support plate, lower template, punch seat, punch, blank holder ring, guide post, guide block; An ejector is fixedly installed at the lower center of the upper base plate, and the lower end of the ejector is fixedly connected to the ejector plate; the die pad is installed below the upper base plate, and a first through hole corresponding to the center of the die is opened in the center for the ejector plate to pass through; the die is fixedly installed below the die pad, and it has a forming cavity with a semi-bowl-shaped outer surface, and the ejector plate is located at the center of the forming cavity. The lower pad has a second through hole at its center through which a second push rod passes. The upper end of the second push rod is fixed to the bottom of the support plate, and the lower end passes through the second through hole and connects to the auxiliary ejection cylinder of the lower working platform of the press. The upper end of the support plate is connected to the lower end of the first push rod, and the upper end of the first push rod passes through the lower template and the punch seat and contacts the pressure ring. The upper end of the support plate is fixedly connected to the lower template, and the lower end is fixedly connected to the lower pad. A guide post is fixedly installed at the edge of the lower template, and the upper end of the guide post slides with the upper base plate. The punch seat is fixed in the center of the lower template, and the punch is fixed on the upper end of the punch seat. The top end of the punch is adapted to the inner surface of the half-bowl. The pressure ring is installed on the outer periphery of the punch and can slide up and down along the outer wall of the punch. Its upper end is used to place the sheet metal to be punched. The lower end of the guide block is fixed on the lower template, and its inner side slides with the pressure ring. Limiting screws are also evenly distributed on the lower template to limit the highest position of the pressure ring sliding upward.

2. The superconducting cavity semi-cavity precision stamping device capable of automatic demolding according to claim 1, characterized in that, The upper end of the ejector plate has a mounting recess that connects to the ejector, and the lower end has a positioning recess that matches the shape of the top end of the punch.

3. The superconducting cavity semi-cavity precision stamping device capable of automatic demolding according to claim 1, characterized in that, An embedded pressure sensor is installed inside the punch to monitor the die contact pressure during the stamping process.

4. The superconducting cavity semi-cavity precision stamping device capable of automatic demolding according to claim 1, characterized in that, The lower template has guide post mounting holes at all four corners, with guide posts installed at three corners and the other corner left empty.

5. The superconducting cavity semi-cavity precision stamping device capable of automatic demolding according to claim 1, characterized in that, The upper base plate and the lower pad are equipped with lifting rods at the four corners, and the surface of the lifting rods is provided with anti-slip knurling for the overall lifting of the mold.

6. The superconducting cavity semi-cavity precision stamping device capable of automatic demolding according to claim 1, characterized in that, The limiting screws include four screws, which are evenly distributed around the punch. One end of each limiting screw is fixedly installed on the lower template, and the upper end extends out after passing through the pressure ring to serve as a limiting end, so as to limit the highest position of the pressure ring sliding upward.

7. A precision stamping method for a superconducting cavity semi-cavity capable of automatic demolding, characterized in that, This method is based on a superconducting cavity semi-cavity precision stamping device capable of automatic demolding as described in any one of claims 1-6, and includes the following steps: S1: Mold installation and cleaning; S2: Stamping; The working platform on the press drives the upper base plate, die pad and die of the superconducting cavity semi-cavity precision stamping device that can automatically demold to move downwards. The relative movement of the punch presses the sheet material to be stamped into the forming cavity of the die. S3: Graded pressure holding stress control; After stamping, a three-stage gradient holding pressure is applied, and the end of the holding pressure is determined. S4: Automatic demolding; After the pressure holding period ends, the working platform on the press returns, and the stamped half cavity is separated from the forming cavity of the die through the first-stage ejection, and the stamped half cavity is separated from the punch through the second-stage ejection. S5: Workpiece removal and cleaning.

8. The precision stamping method for a superconducting cavity semi-cavity capable of automatic demolding according to claim 7, characterized in that, The graded pressure holding stress control in step S3 specifically includes: S31: After the punch reaches the end point, it enters the first stage of pressure holding, and the pressure is maintained at the first pressure value for the first duration to force the sheet metal to be stamped to complete the plastic flow and fill the tiny parts of the mold forming cavity. S32: After the first stage of pressure holding is completed, the pressure is linearly reduced to the second pressure value at the first preset rate, and the second stage of pressure holding begins; during the second stage of pressure holding, the pressure is maintained for a second duration to allow the internal stress of the sheet to redistribute and the elastic aftereffect to be gradually released; S33: After the second stage of pressure holding is completed, the pressure is linearly reduced to the third pressure value at the second preset rate, and the third stage of pressure holding is entered; during the third stage of pressure holding, the pressure is maintained for the third duration so that the elasticity of the sheet tends to the elastic equilibrium state and the rebound trend is weakened. S34: During the last fourth period of the third-stage pressure holding, determine whether the pressure fluctuation is not greater than the first preset pressure threshold and whether the change in the displacement sensor reading is not greater than the first preset displacement value; if so, determine that the current stress release is complete; otherwise, automatically extend the third-stage pressure holding time according to the preset extension rule.

9. The precision stamping method for a superconducting cavity semi-cavity capable of automatic demolding according to claim 8, characterized in that, In step S31, the first pressure value is 120T±1T, and the first duration is 50~70 seconds; In step S32, the second pressure value is 80T±1T, the second duration is 50~70 seconds, and the first preset rate is 4-6T / s; In step S33, the third pressure value is 50T±1T, the third duration is 50~70 seconds, and the second preset rate is 4-6T / s; In step S34, the fourth duration is 8 to 12 seconds, the first preset pressure threshold is 0.3-0.7T, and the first preset displacement value is 0.01-0.03mm.

10. The precision stamping method for a superconducting cavity semi-cavity capable of automatic demolding according to claim 7, characterized in that, The first-stage ejection includes: after the pressure holding period ends, the press upper working platform returns, the upper base plate, the die pad, and the die move upward with the guide post; at the same time, the compression spring inside the ejector recovers its deformation, driving the ejector to eject the stamped half cavity from the die; The secondary ejection includes: the second ejector rod receiving the ejection force and transmitting it to the support plate and the first ejector rod, pushing the pressure ring upward; the edge of the pressure ring pushes the bottom fold of the stamped half cavity, pushing the half bowl out of the punch.

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