Nuclear fusion poloidal field coil VPI mold size precision control system and method

Abstract

The present invention discloses a precision control system and method for the size of a VPI mold for a nuclear fusion poloidal field coil, which relates to the field of research and development of superconducting coils for nuclear fusion, and includes a VPI mold, a support seat, a control unit, a temperature and shear force sensor, a radial sliding module and other parts. When the VPI mold heats and degasses / cures the poloidal field coil through a heating plate, the control unit drives the radial sliding module to move radially through a temperature signal, and the temperature and shear force sensor monitors the shear force between the VPI mold and the support seat, and corrects the displacement of the radial sliding module through a predetermined threshold, thereby accurately controlling the outline size of the VPI mold during the heating, degassing, curing and cooling process. The present invention has the advantages of high automation, high control accuracy, simple structure, strong stability and the like.

Description

Technical Field

[0001] The invention relates to the field of research and development of superconducting coils for nuclear fusion, and in particular to a nuclear fusion poloidal field coil VPI mold size precision control system and method. Background Art

[0002] The Tokamak device is recognized as an ideal device for humans to achieve magnetic confinement nuclear fusion energy, and the magnet system is the core component of the Tokamak device. Fusion energy is proportional to the fourth power of the magnetic field and the third power of the radius. The magnetic field strength determines the most critical factor in the fusion device to produce fusion energy. Therefore, the construction scale of the Tokamak device is constantly expanding. The nuclear fusion superconducting magnet system usually contains 16 poloidal field (TF) magnets, 6 / 7 poloidal field (PF) magnets, 1 central spiral tube (CS) magnet and several correction field (CC) magnets. Among them, the nuclear fusion poloidal field coil has a circular ring profile and is usually manufactured using armored superconducting conductors; armored superconducting conductors are usually CICC (Cable in Conduit Conductor) structures, and the NbTi / Nb3Sn superconducting strands that have been twisted at multiple levels are inserted into 316L stainless steel armor, and the superconducting conductors are manufactured through a multi-stage tube shrinking process; armored superconducting conductors are manufactured through coil winding, joint manufacturing, vacuum pressure impregnation (VPI) and other process flows.

[0003] VPI is an important process in the manufacturing process of poloidal superconducting magnets. Due to the large size of poloidal superconducting coils, VPI and heating curing of the coils are usually completed by on-site construction. After the inter-turn insulation wrapping and joint manufacturing are completed, the poloidal superconducting coils are installed in the inner mold composed of stainless steel plates. The sealed stainless steel inner mold provides a vacuum environment for the inside of the coil; a carbon steel structure or a stainless steel structure is used as an outer mold to keep the contour and cross-sectional dimensions of the poloidal coil in the inner mold. The outer mold is used to maintain the coil size and resist the vacuum and pressing process during the VPI process. At the same time, all mold heating units are usually installed on the VPI outer mold with a heating plate to provide external heating for the coil vacuum heating degassing and heating curing processes; for the poloidal coil, the coil is usually heated internally by passing a large current and a low voltage, and the temperature of the coil is measured by the pre-tested conductor "temperature-resistance" curve, and the internal / external joint heating is finally achieved to heat the coil and degas and heat the insulating resin after injection. During the heating process of the nuclear fusion poloidal field coil, the coil winding made of 316L material and the VPI mold made of carbon steel & stainless steel will experience large heating expansion and cooling contraction during the heating / cooling process under the effect of the thermal expansion coefficient of the material, and relative slip will occur between the VPI mold and the mold support base. Due to the different friction coefficients and the influence of the coil contour structure, the slip and contraction between the VPI mold and the mold support base are highly inconsistent during the heating / cooling process, with great randomness and discreteness, resulting in large contour deviations of the outer contour of the poloidal field coil during the 90°C gel process and the 130°C curing process. The coil contour tolerance will lead to deviations in the center line of the coil current and distortion of the magnetic field configuration during the excitation process.

[0004] Traditional processes usually use materials with low friction coefficients (such as graphite copper, graphite iron, polytetrafluoroethylene plates, etc.) between the VPI mold and the mold support seat to reduce the friction coefficient between the VPI mold and the support seat during the heating / cooling process, thereby achieving the accuracy of the radial movement of the poloidal field coil; this process is affected by multiple factors such as material randomness, discreteness of the machining roughness of the sliding material, and process stability during installation by the operator. In the actual implementation process, it is impossible to achieve precise control of the contour of the large-section and heavy poloidal field coil after VPI. The precise control system and control method of the VPI mold size of the nuclear fusion poloidal field coil directly restrict the development of large-scale nuclear fusion superconducting magnet manufacturing technology. It is urgent to invent a new sliding system and method to achieve precise, stable and closed-loop precision control of the mold size during the VPI process. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a nuclear fusion poloidal field coil VPI mold size precision control system and method, which is used to realize active closed-loop movement between the VPI mold and the mold support base when the outer contour of the coil and the mold changes with temperature during the poloidal field coil VPI manufacturing process, thereby ensuring precise control of the coil size during the coil VPI post-heating and curing process. It has the advantages of high degree of automation, high control accuracy, simple structure, strong stability, etc.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] A nuclear fusion poloidal field coil VPI mold size precision control system comprises a VPI mold, a support seat, a radial sliding module, a temperature and shear force sensor, and a control unit; a plurality of the VPI molds form a circle along the circumference, adjacent VPI molds are fixedly connected, and the interior of a circle of VPI molds together forms a hollow circular ring; the support seat is located between adjacent VPI molds to provide support for the VPI mold and the radial sliding module; the radial sliding module is located between the VPI mold and the support seat, and is fixedly connected to the VPI mold and the support seat; the temperature and shear force sensor is connected to the VPI mold, monitors the parameters of the VPI mold and feeds back to the control unit; the control unit receives the signal of the temperature sensor in the temperature and shear force sensor and controls the radial sliding module to move actively, and the radial sliding module enables the VPI mold to expand and contract and relax in the radial direction; a poloidal field coil is arranged in the hollow circular ring formed by the interior of the circle of VPI molds; the temperature and shear force sensor comprises a temperature sensor and a shear force sensor.

[0008] Furthermore, the VPI mold includes a base frame, a heating plate, a mold vertical side plate, and a mold horizontal side plate; the mold vertical side plates and the mold horizontal side plates together constitute the inner mold of the VPI mold; there are two heating plates, which are respectively located on the upper outer side and the lower outer side of the mold horizontal side plate, and are used to limit the offset of the mold vertical side plates and the mold horizontal side plates; there are two base frames, which are respectively located on the outer sides of the two heating plates and are fixedly connected to the heating plates; the base frame and the heating plates constitute the outer mold of the VPI mold, which are used to maintain the contour and cross-sectional size of the inner mold.

[0009] Furthermore, the material of the mold vertical side plates and the mold horizontal side plates is stainless steel thin plates.

[0010] Furthermore, the base frame is composed of a square tube, and a square plate is welded on the outer side of the base frame.

[0011] Furthermore, the base frame and the heating plate are made of carbon steel structure or stainless steel structure.

[0012] Furthermore, the radial sliding module includes a servo motor, a reducer, a connecting frame, a coupling, a screw, a linear guide, a slide and a base; the linear guide is located on both sides of the length direction of the base; the slide is installed on the linear guide; one end of the reducer is fixedly installed on one side of the connecting frame, and the other end of the reducer is fixedly connected to the servo motor and fixedly connected to the screw through the coupling; the connecting frame is fixedly connected to one end of the base; the screw is installed in the middle of the base and is spirally matched with the slide.

[0013] Furthermore, the slide is in a trapezoidal shape as a whole, and the width of the slide is greater than the width of the base, and greater than twice the width of the square plate of the base frame.

[0014] Furthermore, the reducer is a right-angle planetary reducer for protecting an encoder of a servo motor.

[0015] Furthermore, the connecting frame is a hollow square.

[0016] The present invention also provides a method for precisely controlling the size of a nuclear fusion poloidal field coil VPI mold, wherein a control unit receives a signal from a temperature sensor and controls a radial sliding module to actively move; a pre-calculated "temperature-displacement" curve is introduced into the control unit;

[0017] When the VPI mold is heated, the control unit receives the signal from the temperature sensor and controls the servo motor to move. According to the "temperature-displacement" curve, the VPI mold is controlled to move outward in the radial direction to a predetermined displacement. The shear force sensor serves as a feedback unit to detect whether the shear force between the VPI mold and the support seat after thermal expansion is within the set shear force threshold.

[0018] When the VPI mold is cooled down, the control unit receives the signal from the temperature sensor and controls the servo motor to move. According to the "temperature-displacement" curve, the VPI mold is controlled to move inward along the radius to a predetermined displacement. The shear force sensor is used as a feedback unit to detect whether the shear force between the VPI mold and the support seat after heat shrinkage is within the set shear force threshold.

[0019] The poloidal field coil in the VPI mold achieves precise contraction and expansion in the radial direction as the VPI mold moves during heating and cooling, thereby achieving precise control of the profile of the poloidal field coil; the "temperature-displacement" curve is: with temperature as the X-axis and the radial movement distance of the VPI mold as the Y-axis, the curve is the theoretical distance the VPI mold moves when the temperature increases by 1°C.

[0020] Beneficial effects:

[0021] The present invention solves the problem that the relative slip between the VPI mold and the mold support base cannot be precisely, quantitatively and stably controlled during the VPI heating process of the poloidal field coil, the thermal expansion of the coil and the cooling contraction of the VPI mold. A radial movement closed-loop automatic control system based on "temperature sensor + shear force sensor" as the acquisition and feedback unit is adopted to achieve active, precise and free sliding between the VPI mold and the support base during the heating, degassing and curing process of the large-scale poloidal field coil, which can effectively ensure the overall contour accuracy of the coil in the glue injection stage, gel stage, curing stage and cooling and demolding stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings which are part of the specification of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute improper limitations on the present invention.

[0023] Figure 1 It is a schematic diagram of the overall structure of the nuclear fusion poloidal field coil VPI mold size precision control system of the present invention.

[0024] Figure 2 Schematic diagram of the structure of the VPI mold.

[0025] Figure 3 It is a schematic diagram of the structure of the radial sliding die.

[0026] Figure 4 It is a schematic flow chart of the method for precise control of the size of the nuclear fusion poloidal field coil VPI mold of the present invention.

[0027] Among them, the figure markings are: 1-VPI mold; 2-support seat; 3-radial sliding module; 101-base; 102-heating plate; 103-mold vertical side plate; 104-mold horizontal side plate; 4-temperature and shear force sensor; 301-servo motor; 302-reducer; 303-connecting frame; 304-coupling; 305-screw; 306-linear guide; 307-slide; 308-base; 5-control unit; 6-polar field coil. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other. The present invention is further described below in conjunction with specific embodiments.

[0029] like Figure 1 , Figure 4As shown, the nuclear fusion poloidal field coil VPI mold size precision control system and method of the present invention includes a VPI mold 1, a support seat 2, a radial sliding module 3, a temperature and shear force sensor 4, and a control unit 5. A plurality of the VPI molds 1 form a circle along the circumference, and adjacent VPI molds 1 are fixedly connected to each other, and a hollow ring is formed inside. The support seat 2 is located between adjacent VPI molds 1 to provide support for the VPI mold 1 and the radial sliding module 3. The radial sliding module 3 is located between the VPI mold 1 and the support seat 2, and is fixedly connected to the VPI mold 1 and the support seat 2, and is used to move the VPI mold 1 to expand and contract radially; the temperature and shear force sensor 4 includes a temperature sensor and a shear force sensor, which are connected to the VPI mold 1 to monitor their parameters and feed back to the control unit 5; the poloidal field coil 6 is sleeved in the VPI mold 1.

[0030] like Figure 2 As shown, the VPI mold 1 of the present invention includes a base frame 101, a heating plate 102, a mold vertical side plate 103, and a mold horizontal side plate 104. The mold vertical side plate 103 and the mold horizontal side plate 104 are respectively the left and right contour plates and the upper and lower contour plates of the inner mold of the VPI mold 1, and are made of stainless steel thin plates, and together constitute the inner mold of the VPI mold 1. There are two heating plates 102, which are located on the upper and lower outer sides of the mold horizontal side plate 104. The heating plates 102 are fixed to the mold side mold plate 104 with long screws, and are also used to limit the deviation of the mold vertical side plate 103 and the mold horizontal side plate 104. At the same time, the heating plates 102 can heat the mold vertical side plate 103 and the mold horizontal side plate 104 when heated, providing conduction for the heating of the VPI mold 1. There are two base frames 101, which are respectively located outside the two heating plates 102 and fixedly connected to the heating plates 102. They are mainly composed of square tubes, and square plates are welded on the outside to strengthen the rigidity of the base frame 101 and facilitate connection with the radial sliding module 3. The base frame 101 and the heating plate 102 constitute the outer mold of the VPI mold 1. Both of them adopt carbon steel structure or stainless steel structure, and the contour and cross-sectional dimensions of the inner mold are conformed. The outer mold is used to resist the pressure on the inside of the stainless steel mold during the impregnation process, and at the same time, the shape of the contour of the poloidal field coil 6 is maintained.

[0031] like Figure 3As shown, the radial sliding module 3 of the present invention includes a servo motor 301, a reducer 302, a connecting frame 303, a coupling 304, a screw 305, a linear guide 306, a slide 307 and a base 308. The linear guide 306 is located on both sides of the length direction of the base 308, and is a heavy-duty type. The slide 307 is installed on the linear guide 306, and is trapezoidal as a whole. Its width is greater than the width of the base and greater than twice the width of the square plate of the base 101. The right end of the reducer 302 is fixedly installed on the left side of the connecting frame 303, and the left end is fixedly connected to the servo motor 301, and is fixedly connected to the screw 305 through the coupling 304. Its type is a right-angle planetary reducer, which is beneficial to protecting the encoder of the servo motor 301. The connecting frame 303 is fixedly connected to the left end of the base 308, and is a hollow square as a whole. The screw 305 is installed in the middle of the base 308 and is spirally matched with the slide 307.

[0032] like Figure 4 As shown, the nuclear fusion poloidal field coil VPI mold size precision control system of the present invention also includes a temperature sensor, a shear force sensor and a control unit 5. The temperature sensor and the shear force sensor are connected to the VPI mold 1 to monitor their parameters and feed back to the control unit 5.

[0033] Specifically, the control unit 5 receives the signal from the temperature sensor and controls the radial sliding module 3 to move actively; the pre-calculated "temperature-displacement" curve is introduced into the control unit 5; when the VPI mold 1 is heated, the control unit 5 controls the servo motor 301 to move after receiving the signal from the temperature sensor, and controls the VPI mold 1 to move outward along the radial direction by a predetermined displacement according to the "temperature-displacement" curve, and the shear force sensor is used as a feedback unit to detect whether the shear force between the VPI mold 1 and the support seat 2 after thermal expansion is within the set shear force threshold; when the VPI mold 1 is cooled, the control unit 5 controls the servo motor 301 to move after receiving the signal from the temperature sensor, and controls the VPI mold 1 to move inward along the radial direction by a predetermined displacement according to the "temperature-displacement" curve, and the shear force sensor is used as a feedback unit to detect whether the shear force between the VPI mold 1 and the support seat 2 after thermal contraction is within the set shear force threshold. The poloidal field coil 6 in the VPI mold 1 realizes precise contraction and relaxation in the radial direction as the VPI mold 1 moves during the heating and cooling processes, thereby realizing precise control of the poloidal field coil profile.

[0034] Whether the contraction and expansion of the poloidal field coil 6 are appropriate is determined based on whether the shear force between the VPI mold 1 and the support seat 2 after thermal expansion is within a set shear force threshold.

[0035] The “temperature-displacement” curve is: with temperature as the X-axis and the radial movement distance of the VPI mold 1 as the Y-axis, the theoretical distance moved by the VPI mold 1 when the temperature rises by 1°C is calculated.

Claims

1. A nuclear fusion poloidal field coil VPI mold size precision control system, characterized in that: It includes a VPI mold, a support seat, a radial sliding module, a temperature and shear force sensor, and a control unit; a plurality of the VPI molds form a circle along the circumference, and adjacent VPI molds are fixedly connected, and the interior of a circle of VPI molds together forms a hollow ring; the support seat is located between adjacent VPI molds to provide support for the VPI mold and the radial sliding module; the radial sliding module is located between the VPI mold and the support seat, and is fixedly connected to the VPI mold and the support seat; the temperature and shear force sensor is connected to the VPI mold, monitors the parameters of the VPI mold and feeds back to the control unit; the control unit receives the signal of the temperature sensor in the temperature and shear force sensor and controls the radial sliding module to move actively, and the radial sliding module enables the VPI mold to expand and contract and relax in the radial direction; a poloidal field coil is arranged in the hollow ring formed by the interior of the circle of VPI molds; the temperature and shear force sensor includes a temperature sensor and a shear force sensor; The radial sliding module includes a servo motor, a reducer, a connecting frame, a coupling, a screw, a linear guide, a slide and a base; the linear guides are located on both sides of the length direction of the base; the slide is installed on the linear guide; one end of the reducer is fixedly installed on one side of the connecting frame, and the other end of the reducer is fixedly connected to the servo motor and fixedly connected to the screw through the coupling; the connecting frame is fixedly connected to one end of the base; the screw is installed in the middle of the base and is spirally matched with the slide.

2. A nuclear fusion poloidal field coil VPI mold size precision control system according to claim 1, characterized in that: The VPI mold includes a base frame, a heating plate, a mold vertical side plate, and a mold horizontal side plate; the mold vertical side plate and the mold horizontal side plate together constitute the inner mold of the VPI mold; there are two heating plates, which are respectively located on the upper outer side and the lower outer side of the mold horizontal side plate, and are used to limit the offset of the mold vertical side plate and the mold horizontal side plate; there are two base frames, which are respectively located on the outer sides of the two heating plates and are fixedly connected to the heating plates; the base frame and the heating plates constitute the outer mold of the VPI mold, which are used to maintain the contour and cross-sectional size of the inner mold.

3. A nuclear fusion poloidal field coil VPI mold size precision control system according to claim 2, characterized in that: The material of the mold vertical side plate and the mold horizontal side plate is stainless steel thin plate.

4. A nuclear fusion poloidal field coil VPI mold size precision control system according to claim 2, characterized in that: The base frame is composed of a square tube, and a square plate is welded on the outer side of the base frame.

5. A nuclear fusion poloidal field coil VPI mold size precision control system according to claim 2, characterized in that: The base frame and the heating plate are made of carbon steel structure or stainless steel structure.

6. A nuclear fusion poloidal field coil VPI mold size precision control system according to claim 1, characterized in that: The slide is in a trapezoidal shape as a whole, and the width of the slide is greater than the width of the base, and greater than twice the width of the square plate of the base frame.

7. A nuclear fusion poloidal field coil VPI mold size precision control system according to claim 1, characterized in that: The reducer is a right-angle planetary reducer, which is used to protect the encoder of the servo motor.

8. A nuclear fusion poloidal field coil VPI mold size precision control system according to claim 1, characterized in that: The connecting frame is a hollow square.

9. A control method implemented by using a nuclear fusion poloidal field coil VPI mold size precision control system according to any one of claims 1 to 8, characterized in that: The control unit receives the signal from the temperature sensor and controls the radial sliding module to move actively; the pre-calculated "temperature-displacement" curve is introduced into the control unit; When the VPI mold is heated, the control unit receives the signal from the temperature sensor and controls the servo motor to move. According to the "temperature-displacement" curve, the VPI mold is controlled to move outward in the radial direction to a predetermined displacement. The shear force sensor serves as a feedback unit to detect whether the shear force between the VPI mold and the support seat after thermal expansion is within the set shear force threshold. When the VPI mold is cooled down, the control unit receives the signal from the temperature sensor and controls the servo motor to move. According to the "temperature-displacement" curve, the VPI mold is controlled to move inward along the radius to a predetermined displacement. The shear force sensor is used as a feedback unit to detect whether the shear force between the VPI mold and the support seat after heat shrinkage is within the set shear force threshold. The poloidal field coil in the VPI mold achieves precise contraction and expansion in the radial direction as the VPI mold moves during heating and cooling, thereby achieving precise control of the poloidal field coil profile; the "temperature-displacement" curve is a curve with temperature as the X-axis and the radial movement distance of the VPI mold as the Y-axis, which is the theoretical distance the VPI mold moves when the temperature rises by 1°C.

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