An ultralow temperature three-section circulator and a preparation method thereof

Abstract

The application relates to the technical field of circulators, in particular to an ultralow-temperature three-section circulator and a preparation method thereof, which comprises the following steps: preparing a cavity, determining whether a guide hole is qualified based on the profile straightness of the hole wall of the guide hole; determining whether a rough drilling process is qualified according to a stability characteristic value of a chip removal amount; adjusting the cutting speed of a drill bit according to the overheated chip detection rate of the chip removal, or adjusting the feed amount of a fine drilling stage to complete the machining process of a single deep hole according to the cutting-off efficiency of the chip removal; determining whether the single deep hole is qualified according to the hole diameter uniformity of the deep hole to optimize the preset straightness; under the condition that the single deep hole is qualified, the preparation of the cavity is completed, and the preparation and inspection of the remaining components of the three-section circulator are carried out; and the several components that pass the inspection are assembled to complete the preparation of the ultralow-temperature three-section circulator. The application improves the machining precision of the deep hole in the deep hole machining process of the cavity of the three-section circulator.

Description

A cryogenic three-section circulator and its preparation method Technical Field

[0001] This invention relates to the field of circulator technology, and in particular to an ultra-low temperature three-section circulator and its preparation method. Background Technology

[0002] In extreme environment fields such as aerospace communications, cryogenic superconductivity, and quantum computing, cryogenic three-section circulators serve as key microwave unidirectional transmission devices, undertaking the core functions of isolating reverse signals and protecting front-end equipment. Their performance stability directly determines the system's signal transmission efficiency and anti-interference capability, while the machining precision of the cavity structure is the core prerequisite for ensuring the reliable operation of the circulator in cryogenic environments.

[0003] As the fundamental load-bearing structure of the cryogenic three-section circulator, the cavity needs to fix core components such as the central conductor, ferrite, and permanent magnet through precision-machined deep holes and positioning grooves to ensure the relative positional accuracy of each component, such as the coupling gap between the central conductor and the ferrite, and the perpendicularity of the magnetic field axis to the ferrite surface. Among these, the deep holes on the cavity are a key functional structure: on the one hand, the deep holes need to provide rigid positioning for the support end of the central conductor or the mounting position of the permanent magnet. If the perpendicularity error of the axis exceeds 0.01mm / 100mm, it may cause the coupling area between the central conductor and the ferrite to shift, resulting in a decrease in signal transmission efficiency. On the other hand, the dimensional accuracy of the deep holes directly affects the uniformity of the gap after component assembly. Uneven gaps will lead to stress concentration due to thermal shrinkage of materials at low temperatures, and may even cause microcracks in the ferrite, destroying the non-reciprocal transmission characteristics.

[0004] Currently, the cavity of cryogenic three-section circulators is generally made of oxygen-free copper. Oxygen-free copper, due to its extremely high electrical and thermal conductivity, can effectively reduce signal transmission loss and heat accumulation in cryogenic environments. Simultaneously, its stable cryogenic mechanical properties meet the structural reliability requirements under extreme conditions. However, the high plasticity and low hardness of oxygen-free copper pose significant challenges to deep hole precision machining. On the one hand, during drilling or boring, plastic deformation easily occurs in the contact area between the tool and the material, leading to a "tool deflection" phenomenon, where the actual tool feed trajectory deviates from the preset path, increasing the straightness error of the deep hole axis. On the other hand, the material is prone to tool sticking during cutting; cutting chips adhering to the tool edge disrupt cutting stability, causing periodic fluctuations in the hole diameter and deteriorating surface roughness, further exacerbating reflection loss in signal transmission. For deep holes with large depth-to-diameter ratios, insufficient tool rigidity and cutting heat accumulation amplify machining errors, making it difficult to control the consistency between axis perpendicularity and hole diameter accuracy. This results in a cavity qualification rate of less than 60%, severely restricting the mass production and performance stability of cryogenic circulators.

[0005] Chinese patent application publication number CN105896010A discloses a circulator comprising: a ground layer; a microstrip circuit layer including a first substrate, microstrip circuits symmetrically disposed on opposite sides of the first substrate, and the two microstrip circuits being connected through a first metallized via; a first ferrite and a second ferrite coaxially disposed, with each ferrite corresponding to one of the two microstrip circuits, wherein the first ferrite and the second ferrite are respectively connected to the ground layer; and a permanent magnet coaxially disposed with the first ferrite and the second ferrite, and located on the second ferrite. In the above embodiment, the microstrip circuit is not directly sputtered onto the ferrite, but is achieved by etching the substrate metal plating layer, which reduces the difficulty of the processing technology and improves the consistency of batch processing.

[0006] The existing technology also has the following problems: In the process of preparing the circulator, the high plasticity and low hardness of oxygen-free copper lead to low machining accuracy of the deep holes in the cavity, resulting in poor mass production stability of the circulator. Summary of the Invention

[0007] Therefore, the present invention provides an ultra-low temperature three-section circulator and its preparation method to overcome the problem in the prior art that the high plasticity and low hardness of oxygen-free copper leads to low machining accuracy of deep holes in the cavity machining process, resulting in poor mass production stability of the circulator.

[0008] To achieve the above objectives, in one aspect, the present invention provides a method for preparing a cryogenic three-section circulator, comprising:

[0009] Prepare a cavity, pre-drill a guide hole at the location to be drilled in the cavity blank, and determine whether the guide hole is qualified based on the comparison result of the outline straightness of the guide hole wall and the preset straightness.

[0010] Under the condition that the guide hole is qualified, the rough drilling stage is entered. The chip removal of the rough drilling stage is obtained so as to determine whether the rough drilling process is qualified based on the stability characterization value of the chip removal amount.

[0011] If the rough drilling process is found to be unqualified, several speed adjustment coefficients are set according to the overheated chip detection rate of the chip removal to adjust the cutting speed of the drill bit, and the speed adjustment coefficients are optimized according to the chip removal efficiency, or the feed rate of the fine drilling stage is adjusted to enter the fine drilling stage to complete the machining process of a single deep hole.

[0012] The hole diameter uniformity of the deep hole is obtained to determine whether a single deep hole is qualified, and the preset straightness is optimized based on the determination result of a single deep hole being unqualified;

[0013] The cavity is prepared after the individual deep holes are deemed qualified. Several components of the three-section circulator are prepared and inspected. The qualified components are then assembled in sequence to complete the preparation of the cryogenic three-section circulator.

[0014] Furthermore, the process of determining the straightness of the guide hole profile includes:

[0015] The guide hole is divided into several circular rings at equal intervals along the axial direction;

[0016] Determine the center of any one of the rings, and connect several of the centers to form an axis;

[0017] Align the axis with the ideal axis of the guide hole;

[0018] The maximum distance between the points where the axis does not coincide with the ideal axis is determined as the straightness of the guide hole wall profile.

[0019] Furthermore, the process of determining whether the guide hole is qualified based on the straightness of the profile includes:

[0020] Compare the straightness of the contour with a preset straightness;

[0021] The guide hole is deemed qualified based on the comparison result that the straightness of the contour is less than or equal to the preset straightness.

[0022] Furthermore, the process of determining the stability characterization value of the chip removal volume includes:

[0023] A chip removal curve is established based on the real-time chip removal volume during the rough drilling process;

[0024] Based on the chip removal curve, a preset chip removal range is constructed with the first preset chip removal amount and the second preset chip removal amount as the vertical axis values ​​respectively;

[0025] The area of ​​the chip removal curve that exceeds the preset chip removal range is determined as the stability characterization value of the chip removal amount.

[0026] Furthermore, assuming the guide hole is qualified, the process of determining whether the rough drilling process is qualified based on the stability characterization value of the chip removal amount includes:

[0027] The stability characterization value is compared with the preset characterization value;

[0028] Based on the comparison result that the stability characterization value is greater than the preset characterization value, the rough drilling process is determined to be unqualified.

[0029] Furthermore, under the condition that the rough drilling process is deemed unqualified, the process of adjusting the drill bit's cutting speed based on the overheated chip detection rate of the chip removal includes:

[0030] The overheated chip detection rate is compared with the preset detection rate;

[0031] The cutting speed of the drill bit is reduced based on the comparison result that the overheated chip detection rate is greater than the preset detection rate;

[0032] Specifically, several speed adjustment coefficients are set based on the comparison result of the first detection rate difference between the overheated chip detection rate and the preset detection rate and the preset difference, so as to reduce the cutting speed based on the several speed adjustment coefficients.

[0033] Furthermore, under the condition that the roughing drilling process is unqualified, the process of adjusting the feed rate of the finishing drilling stage based on the overheated chip detection rate of the chip removal includes:

[0034] The overheated chip detection rate is compared with the preset detection rate;

[0035] The feed rate for the fine drilling stage is reduced based on the comparison result that the overheated chip detection rate is less than or equal to the preset detection rate.

[0036] Specifically, several feed rate adjustment coefficients are set based on the comparison result of the second detection rate difference between the preset detection rate and the overheated chip detection rate and the preset difference, so as to reduce the feed rate based on several feed rate adjustment coefficients.

[0037] Furthermore, under the condition of reducing the cutting speed of the drill bit, the process of optimizing the speed adjustment coefficient based on the chip removal efficiency includes:

[0038] The cutting efficiency is compared with the preset efficiency;

[0039] The speed adjustment coefficient is optimized based on the comparison result that the cutting efficiency is less than the preset efficiency;

[0040] Among them, several speed optimization coefficients are set based on the comparison result of the efficiency difference between the preset efficiency and the cutting efficiency and the preset efficiency difference, so as to optimize the speed adjustment coefficient based on the several speed optimization coefficients.

[0041] Furthermore, the process of optimizing the preset straightness based on the pore diameter uniformity of the deep hole includes:

[0042] The aperture uniformity is compared with a preset uniformity.

[0043] The preset straightness is optimized based on the comparison result that the aperture uniformity is greater than the preset uniformity;

[0044] Specifically, several straightness optimization coefficients are set based on the comparison result of the uniformity difference between the aperture uniformity and the preset uniformity, so as to optimize the preset straightness based on the several straightness optimization coefficients.

[0045] On the other hand, the present invention also provides a cryogenic three-section circulator, comprising:

[0046] Magnetic shielding cover, used to shield magnetic fields;

[0047] A magnetic field assembly, which is disposed within the magnetic shield, includes a plurality of samarium cobalt permanent magnets for providing a stable bias magnetic field, and an iron-nickel alloy arranged symmetrically on the upper and lower sides of the samarium cobalt permanent magnets for optimizing the magnetic field distribution.

[0048] A signal transmission component, disposed in the middle of the magnetic field component, includes a central conductor for transmitting microwave signals and an absorbing load for absorbing reverse signals.

[0049] A support assembly includes a cavity for fixing the magnetic field assembly and the signal transmission assembly, and a plurality of ceramic rings for isolating the central conductor from the cavity, wherein the cavity includes an upper cavity and a lower cavity.

[0050] Compared with the prior art, the beneficial effects of this invention are as follows: In the process of fabricating the cavity using oxygen-free copper in the preparation of the circulator, the high plasticity and low hardness of oxygen-free copper lead to low precision in deep hole machining. Firstly, the quality of the guide hole is determined. As the reference guiding structure for deep hole machining, the precision of the guide hole directly affects the stability of the subsequent tool feed trajectory. The high plasticity of oxygen-free copper easily causes tool deflection due to radial force fluctuations in the early stages of cutting. A qualified guide hole provides rigid constraint to the tool through precise axial positioning. After the tool edge enters the guide hole, its radial displacement is restricted. Within the tolerance range of the guide hole diameter, trajectory deviation caused by material plastic deformation should be avoided. Simultaneously, the perpendicularity of the guide hole axis directly determines the initial directional reference for deep hole machining, guiding the deep hole tool to feed along a preset vertical direction. It is crucial to ensure that the perpendicularity error between the deep hole axis and the cavity reference surface (such as the ferrite mounting surface) is ≤0.01mm / 100mm. This perpendicularity error is fundamental for the subsequent assembly and positioning of components such as the center conductor and permanent magnet, preventing magnetic field coupling offset or uneven signal transmission gaps caused by axis tilt. Therefore, further monitoring during the rough drilling stage is necessary after confirming the guide hole's compliance. During rough drilling, the high plasticity of oxygen-free copper makes the radial cutting force extremely sensitive to chip morphology. A stable chip evacuation rate means that the contact area between the tool and chips, frictional resistance, and shear force distribution are uniform, avoiding instantaneous peaks or sudden drops in cutting force. Simultaneously, oxygen-free copper has a high thermal conductivity; however, if cutting heat accumulates between the tool and the hole wall due to poor chip evacuation, it can cause a sudden increase in local temperature, further increasing the material's plasticity and making it prone to tool sticking. A stable chip evacuation rate can remove more than 70% of the cutting heat through the chips, keeping the tool operating temperature below the softening critical temperature of oxygen-free copper and preventing material defects. Softening causes extrusion deformation of the hole wall or the formation of chip lumps on the tool surface, thus ensuring the surface roughness of the hole wall. Although oxygen-free copper chips have low hardness, if continuous long chips are wrapped or accumulated in the hole, they will rub and scrape against the hole wall as the tool rotates. Stable chip removal can be achieved by controlling the chip shape, allowing the chips to be smoothly discharged along the chip removal channel, avoiding contact with the hole wall, and thus reducing the degree of chip scratching on the hole wall. Under the condition that the rough drilling process is unqualified, the cutting speed of the drill bit in the rough drilling stage can be reduced, or the feed rate in the fine drilling stage can be reduced to improve the machining accuracy of deep holes, thereby improving the batch production stability of the circulator.

[0051] Furthermore, this invention determines the qualification of a single deep hole based on its diameter uniformity after the deep hole machining process is completed. If the diameter uniformity is qualified, it indicates that machining parameters such as cutting force, tool wear, and chip removal are stable, and the dimensional accuracy of the deep hole meets design requirements, which is a fundamental prerequisite for quality qualification. It also indicates that the tool has not deviated, the material has not undergone plastic deformation due to uneven local stress, and the cylindricity and straightness errors of the deep hole can be controlled within design requirements, indicating qualified shape accuracy. For the oxygen-free copper cavity of the cryogenic three-section circulator, the core function of the deep hole is to provide precise assembly space for core components such as ferrite and the central conductor; its diameter uniformity directly... The fit between the ferrite and the deep hole in the cavity affects assembly accuracy and product function. The fit clearance between the ferrite and the cavity must be controlled within the design range to ensure thermal compatibility and signal transmission stability under ultra-low temperature conditions. If the gap is too large, it can easily cause the ferrite to shift, resulting in a decrease in signal isolation. If the gap is too small, it can easily cause extrusion stress due to ultra-low temperature shrinkage, leading to ferrite breakage or cavity deformation. Oxygen-free copper will generate stress due to thermal shrinkage at ultra-low temperatures. Areas with poor hole uniformity will become stress concentration points. After several thermal cycles, microcracks may appear, ultimately affecting the service life of the circulator. This invention improves the pass rate of the guide hole by addressing the judgment result of a single unqualified deep hole. Attached Figure Description

[0052] Figure 1 is a flowchart of the preparation method of the cryogenic three-section circulator according to an embodiment of the present invention;

[0053] Figure 2 is a flowchart illustrating the process of determining whether the guide hole is qualified according to an embodiment of the present invention;

[0054] Figure 3 is a flowchart of an embodiment of the present invention for determining whether the rough drilling process is qualified;

[0055] Figure 4 is a schematic diagram of the overall structure of the cryogenic three-section circulator according to an embodiment of the present invention;

[0056] Figure 5 is an exploded view of the cryogenic three-section circulator according to an embodiment of the present invention;

[0057] In the diagram: 1. Top cover plate, 2. First 1J38 iron-nickel alloy, 3. First samarium cobalt permanent magnet, 4. First 1J36 iron-nickel alloy, 5. Upper cavity, 6. First ceramic ring, 7. Absorbing load, 8. Center conductor, 9. Second ceramic ring, 10. Lower cavity, 11. Second 1J36 iron-nickel alloy, 12. Second samarium cobalt permanent magnet, 13. Second 1J38 iron-nickel alloy, 14. Side cover plate, 15. Lower cover plate, 16. Rear cover plate, 17. SMA connector, 18. Front cover plate, 19. Magnetic shielding cover, 20. First circular cavity, 22. Second circular cavity, 23. Third circular cavity. Detailed Implementation

[0058] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0059] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0060] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0061] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0062] Please refer to Figures 1-3. Figure 1 is a flowchart of the preparation method of the cryogenic three-section circulator according to an embodiment of the present invention; Figure 2 is a flowchart of determining whether the guide hole is qualified according to an embodiment of the present invention; Figure 3 is a flowchart of determining whether the rough drilling process is qualified according to an embodiment of the present invention.

[0063] The method for preparing an ultra-low temperature three-section circulator according to an embodiment of the present invention includes:

[0064] Step S1: Prepare the cavity. Pre-drill a guide hole at the location to be drilled in the cavity blank. Determine whether the guide hole is qualified based on the comparison result of the outline straightness of the guide hole wall with the preset straightness. The cavity includes an upper cavity and a lower cavity.

[0065] Step S2: Under the condition that the guide hole is qualified, proceed to the rough drilling stage, obtain the chip removal of the rough drilling stage, and determine whether the rough drilling process is qualified based on the stability characterization value of the chip removal amount.

[0066] Step S3: Under the condition that the rough drilling process is unqualified, set several speed adjustment coefficients according to the overheated chip detection rate of the chip removal to adjust the cutting speed of the drill bit, and optimize the speed adjustment coefficients according to the chip removal efficiency, or adjust the feed rate of the fine drilling stage to enter the fine drilling stage to complete the machining process of a single deep hole.

[0067] Step S4: Obtain the hole diameter uniformity of the deep hole to determine whether a single deep hole is qualified, and optimize the preset straightness based on the determination result of a single deep hole being unqualified;

[0068] Step S5: Under the condition that the individual deep hole is qualified, the cavity is prepared, and several components of the three-section circulator are inspected. The qualified components are assembled in the assembly sequence to complete the preparation of the three-section circulator.

[0069] Specifically, the testing methods for each component of the three-section circulator are all existing technologies. For example, a gaussmeter is used to detect the magnetic field of the samarium cobalt permanent magnet to test the magnetic properties of the three-section circulator, and a microwave signal analyzer is used to detect the transmission characteristics of the center conductor to test the electrical properties of the three-section circulator. No specific limitations are imposed.

[0070] Specifically, the assembly sequence of the three-section circulator is as follows: first, install the magnetic field component; then, install the signal transmission component; and finally, install the magnetic shielding cover. The assembly accuracy is ensured by positioning with tooling fixtures (such as cavity positioning jigs). This is existing technology and will not be elaborated further.

[0071] Specifically, when pre-drilling guide holes at the locations to be drilled in the cavity blank, a stepped pre-drilling strategy is adopted. Multiple drill bits are used to gradually approach the final hole diameter, reducing stress concentration in a single cut. This is existing technology and will not be elaborated further.

[0072] Specifically, the process of determining the straightness of the guide hole profile includes:

[0073] The guide hole is divided into several circular rings at equal intervals along the axial direction;

[0074] Determine the center of any one of the rings, and connect several of the centers to form an axis;

[0075] Align the axis with the ideal axis of the guide hole;

[0076] The maximum distance between the points where the axis does not coincide with the ideal axis is determined as the straightness of the guide hole wall profile.

[0077] Specifically, the ideal axis of the guide hole refers to the reference straight line required by the design, and the maximum distance between the axis and the ideal axis directly corresponds to the most skewed position of the hole.

[0078] Specifically, the guide hole is divided into rings at preset distances along its axial direction to ensure full length coverage. For example, a 30mm deep guide hole is divided into 6 rings at a preset distance of 5mm. Sampling points are added in the 0-5mm inlet section, the 15mm-20mm heating intermediate section, and the 25mm-30mm heating outlet section, with the spacing reduced to 2.5mm, to capture possible areas of concentrated deformation. The specific method is not limited.

[0079] Specifically, the process of determining whether the guide hole is qualified based on the straightness of the profile includes:

[0080] Compare the straightness of the contour with a preset straightness;

[0081] The guide hole is deemed qualified based on the comparison result that the straightness of the contour is less than or equal to the preset straightness;

[0082] The guide hole is determined to be unqualified based on the comparison result that the straightness of the contour is greater than the preset straightness.

[0083] Specifically, the preset straightness value range is set to [0.003mm, 0.006mm], and in this embodiment of the invention, 0.005mm is preferred.

[0084] Specifically, the process of determining the stability characterization value of chip removal volume includes:

[0085] A chip removal curve is established based on the real-time chip removal volume during the rough drilling process;

[0086] Based on the chip removal curve, a preset chip removal range is constructed with the first preset chip removal amount and the second preset chip removal amount as the vertical axis values ​​respectively;

[0087] The area of ​​the chip removal curve that exceeds the preset chip removal range is determined as the stability characterization value of the chip removal amount.

[0088] It is understood that two parallel straight lines are set on the chip removal curve with the first preset chip removal amount and the second preset chip removal amount as the vertical axis, and the range between the two straight lines is the preset chip removal amount range.

[0089] Specifically, the range of the second preset chip removal amount is set to [1.1Q]. avg 1.2Q avg In this embodiment of the invention, 1.15Q is preferred. avg The first preset chip removal amount is set to a value range of [0.75Q]. avg 0.9Q avg In this embodiment of the invention, 0.8Q is preferred. avg The Q avgThe average chip removal rate refers to the average chip removal rate per unit time or unit cutting length. It is determined based on historical cutting processes. At least 50 deep hole machining processes with the required machining accuracy are selected, and the real-time chip removal rate curves of the 50 machining processes are integrated respectively. The average value of the ratio of all integral values ​​to the total time is taken.

[0090] Specifically, assuming the guide hole is qualified, the process of determining whether the rough drilling process is qualified based on the stability characterization value of the chip removal amount includes:

[0091] The stability characterization value is compared with the preset characterization value;

[0092] Based on the comparison result that the stability characterization value is greater than the preset characterization value, the rough drilling process is determined to be unqualified.

[0093] The rough drilling process is deemed qualified based on the comparison result that the stability characterization value is less than or equal to the preset characterization value.

[0094] Specifically, the range of the preset characterization value is set to [3mm]. 2 8mm 2 In this embodiment of the invention, 6mm is preferred. 2 .

[0095] Specifically, the process of adjusting the drill bit's cutting speed based on the overheated chip detection rate, when the rough drilling process is determined to be substandard, includes:

[0096] The overheated chip detection rate is compared with the preset detection rate;

[0097] The cutting speed of the drill bit is reduced based on the comparison result that the overheated chip detection rate is greater than the preset detection rate;

[0098] Specifically, several speed adjustment coefficients are set based on the comparison result of the first detection rate difference between the overheated chip detection rate and the preset detection rate and the preset difference, so as to reduce the cutting speed based on the several speed adjustment coefficients.

[0099] Specifically, based on the comparison result that the first detection rate difference is greater than the preset difference, it is determined to reduce the cutting speed by a first speed adjustment coefficient;

[0100] Based on the comparison result that the first detection rate difference is less than or equal to the preset difference, the cutting speed is reduced by the second speed adjustment coefficient.

[0101] Specifically, the core objective of rough drilling is to quickly remove excess material. If the rough drilling process is substandard, it can easily lead to overheating. A sudden increase in chip removal causes a large amount of chips to accumulate at the drill tip or in the chip grooves, forming a heat-insulating layer that hinders the cooling fluid from reaching the cutting zone, resulting in a sharp drop in heat dissipation efficiency. Conversely, a sudden decrease in chip removal may be due to chips clogging the chip grooves. In this case, the chips continue to rub against the tool, accumulating frictional heat and causing localized overheating. Furthermore, high temperatures can soften workpiece materials such as steel and aluminum, increasing their plasticity. Chips easily stick to the drill bit edge or in the chip grooves, causing blockage. Blocked chips further disrupt the continuity of chip removal, sometimes accumulating and then suddenly bursting out (a sudden increase in chip removal), and sometimes the blockage causes a sudden decrease in chip removal, further exacerbating the fluctuations in the chip removal curve and creating a vicious cycle of overheating, tool sticking, chip fluctuations, and increased risk of overheating. Reducing the cutting speed directly reduces frictional heat between the tool and the workpiece, suppressing overheated chips at the source, breaking the cycle, and gradually restoring chip removal stability.

[0102] Specifically, the overheat detection rate is determined based on the color of the chips. During drilling, excessively high temperatures can cause oxidation on the surface of the billet, leading to a change in the color of the cut chips. Under normal conditions, oxygen-free copper chips are light rose-colored with a bright surface and no obvious black or dark brown oxide layer. However, at high temperatures, oxidation produces copper oxide, resulting in black or dark brown chips. Therefore, the mass ratio of overheated chips can be indirectly determined by combining image information and auxiliary parameters of the chips: First, overheated chips are detected by an image recognition algorithm based on their grayscale value (e.g., less than 100 indicates an overheated chip). Then, the volume of a single overheated chip is calculated based on the pixel size of the image, and the mass of a single overheated chip is calculated by combining the density of the chip material. After calculating the total mass of all overheated chips within a period, the percentage of this mass compared to the total mass of chips discharged during the same period (which can be directly measured by a weighing sensor or calculated using a chip discharge model) gives the mass ratio of overheated chips. The overheat detection rate is the mass ratio of overheated chips per unit time.

[0103] Specifically, the overheat detection rate is set to a range of [5%, 10%], preferably 7% in this embodiment of the invention; the preset difference is set to a range of [2%, 5%], preferably 3% in this embodiment of the invention; the first speed adjustment coefficient is set to a range of [0.7, 0.8], preferably 0.75 in this embodiment of the invention; and the second speed adjustment coefficient is set to a range of [0.81, 0.9], preferably 0.85 in this embodiment of the invention.

[0104] Specifically, when the roughing process is determined to be substandard, the process of adjusting the feed rate for the finishing drilling stage based on the overheated chip detection rate of the chip removal includes:

[0105] The overheated chip detection rate is compared with the preset detection rate;

[0106] The feed rate for the fine drilling stage is reduced based on the comparison result that the overheated chip detection rate is less than or equal to the preset detection rate.

[0107] Specifically, several feed rate adjustment coefficients are set based on the comparison result of the second detection rate difference between the preset detection rate and the overheated chip detection rate and the preset difference, so as to reduce the feed rate based on several feed rate adjustment coefficients.

[0108] Specifically, based on the comparison result that the second detection rate difference is greater than the preset difference, the feed rate is reduced by the first feed rate adjustment coefficient.

[0109] Based on the comparison result that the second detection rate difference is less than or equal to the preset difference, the feed rate is reduced by the second feed rate adjustment coefficient.

[0110] Specifically, when the rough drilling process fails, poor chip removal stability indicates significant fluctuations in cutting force. The core requirement for the finish drilling stage is to ensure the dimensional and positional accuracy of the hole. Maintaining the original feed rate, which is positively correlated with cutting force, will further amplify cutting force fluctuations, leading to drill bit wobble and increased vibration. This can ultimately cause dimensional deviations (such as larger hole diameter or hole axis tilt) or surface ripples in the finish drilling stage. Reducing the feed rate decreases the cutting load per unit time, making the cutting process smoother and preventing the force fluctuations from worsening in the finish drilling stage. Simultaneously, reducing the feed rate also controls the cutting temperature, preventing overheating that can lead to quality and tool failure. Overheated chips generated during a failed rough drilling process indicate that the cutting zone temperature has exceeded the material's reasonable machining temperature range. If the original feed rate is used in the finish drilling stage, it will cause friction between the chips and the tool rake face. Extended rubbing time and increased friction area will further raise the cutting temperature, leading to thermal wear of the tool and subsequently causing hole wall burns or dimensional drift. Reducing the feed rate can reduce the frictional load between the chips and the tool, lowering the cutting temperature by 15% to 30%, preventing the risk of overheating from being transferred to finish drilling, and extending tool life. In addition, adapting to the pre-machining state of the rough drilling process can reduce subsequent quality problems. Unsatisfactory rough drilling may be accompanied by uneven residual stress on the hole wall and out-of-tolerance hole diameter. As the final forming process, finish drilling requires flexible cutting by reducing the feed rate to reduce secondary extrusion on the hole wall of the rough drill, avoid hole deformation caused by residual stress release, and at the same time correct the small dimensional errors of the rough drill through smooth cutting to ensure the final hole accuracy is qualified.

[0111] Specifically, the value range of the first feed rate adjustment coefficient is set to [0.5, 0.7], and 0.6 is preferred in this embodiment of the invention. The value range of the second feed rate adjustment coefficient is set to [0.71, 0.9], and 0.8 is preferred in this embodiment of the invention.

[0112] Specifically, the process of optimizing the speed adjustment coefficient based on the chip removal efficiency, under the condition of reducing the drill bit's cutting speed, includes:

[0113] The cutting efficiency is compared with the preset efficiency;

[0114] The speed adjustment coefficient is optimized based on the comparison result that the cutting efficiency is less than the preset efficiency;

[0115] Among them, several speed optimization coefficients are set based on the comparison result of the efficiency difference between the preset efficiency and the cutting efficiency and the preset efficiency difference, so as to optimize the speed adjustment coefficient based on the several speed optimization coefficients.

[0116] Specifically, based on the comparison result that the efficiency difference is greater than the preset efficiency difference, the speed adjustment coefficient is increased by a first speed optimization coefficient.

[0117] Based on the comparison result that the efficiency difference is less than or equal to the preset efficiency difference, the speed adjustment coefficient is increased by the second speed optimization coefficient.

[0118] Specifically, the core reason for optimizing the speed adjustment coefficient is to balance the contradiction between suppressing overheating and ensuring smooth chip removal, and to avoid new machining problems caused by simply reducing the cutting speed. The purpose of reducing the cutting speed is to solve the overheating problem when the rough drilling is unqualified. However, if the cutting speed is too low, it will have side effects. If the cutting temperature is too low, the plastic deformation ability of the chip material will decrease, making it difficult to break under the action of the drill bit chip breaker. The cutting force is insufficient, and it is not possible to effectively cut the continuous chips into short segments. It is easy to form long curled chips / ribbon chips, which will then wrap around the drill bit, block the chip removal channel, and cause new problems such as drill bit chipping, hole position deviation, and machining interruption.

[0119] Specifically, the cutting efficiency refers to the percentage of chip segments that meet the fracture criteria per unit time out of the total number of chip segments. This can be statistically analyzed by using a visual recognition system to capture images of the chip flow. The length of the chips that meet the fracture criteria is less than or equal to 2 to 3 times the aperture and there is no continuous entanglement.

[0120] Specifically, the preset efficiency is set to a range of [87%, 94%], preferably 92% in this embodiment of the invention; the preset efficiency difference is set to a range of [3%, 6%], preferably 4% in this embodiment of the invention; the first speed optimization coefficient is set to a range of [1.1, 1.2], preferably 1.15 in this embodiment of the invention; and the second speed optimization coefficient is set to a range of [1.01, 1.09], preferably 1.05 in this embodiment of the invention.

[0121] Specifically, the process of optimizing the preset straightness based on the pore diameter uniformity of deep holes includes:

[0122] The aperture uniformity is compared with a preset uniformity.

[0123] The preset straightness is optimized based on the comparison result that the aperture uniformity is greater than the preset uniformity;

[0124] Based on the comparison result that the aperture uniformity is less than or equal to the preset uniformity, it is determined that the preset straightness will not be optimized.

[0125] Specifically, several straightness optimization coefficients are set based on the comparison result of the uniformity difference between the aperture uniformity and the preset uniformity, so as to optimize the preset straightness based on the several straightness optimization coefficients.

[0126] Specifically, the process of determining the aperture uniformity includes:

[0127] The deep hole is divided into several circumferential sections at equal intervals along its axial position, wherein the annulus refers to the circumference of the cross section corresponding to the axial position of the deep hole;

[0128] The position of the reference axis is determined by taking the center of the first circumferential section as the starting point of the reference axis of the deep hole.

[0129] The intersection of the reference axis and the plane containing any of the circumferential cross sections is determined as the reference point of the circumferential cross section;

[0130] Establish mutually perpendicular cross measurement lines with the reference point as the center, determine the distance from the intersection of the cross measurement line and the circumference of the circumferential section to the reference point, so as to obtain several spacings corresponding to any circumferential section. The two lines of the cross measurement line both pass through the reference point and are perpendicular to the axis of the deep hole. Each cross measurement line corresponds to two spacings, for a total of four spacings.

[0131] The standard deviation of the maximum absolute difference of several of the aforementioned spacings is determined as the aperture uniformity.

[0132] Specifically, based on the comparison result that the uniformity difference is greater than the preset uniformity difference, a first straightness optimization coefficient is determined to increase the preset straightness;

[0133] Based on the comparison result that the uniformity difference is less than or equal to the preset uniformity difference, a second straightness optimization coefficient is determined to increase the preset straightness.

[0134] Specifically, the preset uniformity is set to a range of [0.001mm, 0.003mm], preferably 0.002mm in this embodiment; the preset uniformity difference is set to a range of [0.0005mm, 0.001mm], preferably 0.0008mm in this embodiment; the first straightness optimization coefficient is set to a range of [1.15, 1.2], preferably 1.18 in this embodiment; and the second straightness optimization coefficient is set to a range of [1.07, 1.14], preferably 1.12 in this embodiment.

[0135] Please refer to Figures 4 and 5. Figure 4 is a schematic diagram of the overall structure of the cryogenic three-section circulator according to an embodiment of the present invention; Figure 5 is an exploded view of the cryogenic three-section circulator according to an embodiment of the present invention.

[0136] This invention provides a cryogenic three-section circulator, comprising:

[0137] A support assembly includes a cavity for fixing the magnetic field assembly and the signal transmission assembly, and a first ceramic ring 6 and a second ceramic ring 9 for isolating the central conductor 8 from the cavity, wherein the cavity includes an upper cavity 5 and a lower cavity 10, the upper cavity 5 and the lower cavity 10 are disposed opposite to each other, and the central conductor 8 is sandwiched between the first ceramic ring 6 and the second ceramic ring 9;

[0138] The upper cavity 5, the lower cavity 10, the first ceramic ring 6, and the second ceramic ring 9 are each provided with three sets of circular cavities;

[0139] The three sets of circular cavities respectively symmetrically house the magnetic field component and the signal transmission component;

[0140] The magnetic field assembly includes a first samarium cobalt permanent magnet 3 and a second samarium cobalt permanent magnet 12 for providing a stable bias magnetic field; a first 1J38 iron-nickel alloy 2 and a first 1J36 iron-nickel alloy 11 symmetrically arranged on the upper and lower sides of the first samarium cobalt permanent magnet 3 for optimizing the magnetic field distribution; and a second 1J38 iron-nickel alloy 13 and a second 1J36 iron-nickel alloy 11 symmetrically arranged on the upper and lower sides of the second samarium cobalt permanent magnet 12 for optimizing the magnetic field distribution. The first samarium cobalt permanent magnet 3, the first 1J38 iron-nickel alloy 2 and the first 1J36 iron-nickel alloy 4 are sequentially housed in the upper cavity 5, and the second samarium cobalt permanent magnet 12, the second 1J38 iron-nickel alloy 13 and the second 1J36 iron-nickel alloy 11 are sequentially housed in the lower cavity 10.

[0141] The magnetic shielding cover 19, which is used to shield the magnetic field, includes an upper cover plate 1 fixedly connected to the top of the upper cavity 5, a lower cover plate 15 fixedly connected to the bottom of the lower cavity 10, a front cover plate 18 fixedly connected to the front surface of the upper cavity 5 and the lower cavity 10, a rear cover plate 16 fixedly connected to the rear surface of the upper cavity 5 and the lower cavity 10, and a side cover plate 14 fixedly connected to the rear surface of the upper cavity 5 and the lower cavity 10.

[0142] The signal transmission component includes a central conductor 8 disposed between the first ceramic ring 6 and the second ceramic ring 9 for transmitting microwave signals, a ferrite for absorbing reverse transmitted signals, and an absorbing load 7 disposed between the first ceramic ring 6 and the second ceramic ring 9 for absorbing reverse signals.

[0143] The connection assembly includes a plurality of SMA connectors 17 fixedly mounted on the upper cavity 5 and the lower cavity 10 for connection with the workpiece under test, wherein the number of the SMA connectors 17 is five.

[0144] The materials used for each component in this embodiment of the invention are all commonly used materials in the prior art, and are not specifically limited.

[0145] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a cryogenic three-section circulator, characterized in that, include: Prepare a cavity, pre-drill a guide hole at the location to be drilled in the cavity blank, and determine whether the guide hole is qualified based on the comparison result of the contour straightness of the guide hole wall with the preset straightness; if the guide hole is qualified, proceed to the rough drilling stage, obtain the chip removal in the rough drilling stage, and determine whether the rough drilling process is qualified based on the stability characterization value of the chip removal amount; if the rough drilling process is unqualified, set several speed adjustment coefficients according to the overheated chip detection rate of the chip removal to adjust the cutting speed of the drill bit, and optimize the speed adjustment coefficients according to the chip removal cutting efficiency, or adjust the feed rate in the fine drilling stage to enter the fine drilling stage to complete the machining process of a single deep hole; The hole diameter uniformity of the deep hole is obtained to determine whether a single deep hole is qualified, and the preset straightness is optimized based on the determination result of a single deep hole being unqualified; The cavity is prepared after the individual deep holes are deemed qualified. Several components of the three-section circulator are prepared and inspected. The qualified components are then assembled in sequence to complete the preparation of the cryogenic three-section circulator.

2. The method for preparing the cryogenic three-section circulator according to claim 1, characterized in that, The process of determining the straightness of the guide hole profile includes: dividing the guide hole into several rings at equal intervals along the axial direction; determining the center of any ring and connecting the several ring centers to form an axis; aligning the axis with the ideal axis of the guide hole; and determining the maximum distance between the positions where the axis and the ideal axis do not coincide as the straightness of the guide hole profile.

3. The method for preparing an ultra-low temperature three-section circulator according to claim 2, characterized in that, The process of determining whether the guide hole is qualified based on the contour straightness includes: comparing the contour straightness with a preset straightness; and determining that the guide hole is qualified based on the comparison result that the contour straightness is less than or equal to the preset straightness.

4. The method for preparing an ultra-low temperature three-section circulator according to claim 3, characterized in that, The process of determining the stability characterization value of chip removal includes: establishing a chip removal curve based on the real-time chip removal volume during the rough drilling process; constructing a preset chip removal volume range based on the chip removal curve with a first preset chip removal volume and a second preset chip removal volume as the ordinate values; and determining the area of ​​the chip removal curve that exceeds the preset chip removal volume range as the stability characterization value of the chip removal volume.

5. The method for preparing an ultra-low temperature three-section circulator according to claim 4, characterized in that, Under the condition that the guide hole is qualified, the process of determining whether the rough drilling process is qualified based on the stability characterization value of the chip removal amount includes: comparing the stability characterization value with a preset characterization value; and determining that the rough drilling process is unqualified based on the comparison result that the stability characterization value is greater than the preset characterization value.

6. The method for preparing an ultra-low temperature three-section circulator according to claim 5, characterized in that, Under the condition that the rough drilling process is unqualified, the process of adjusting the cutting speed of the drill bit based on the overheated chip detection rate includes: comparing the overheated chip detection rate with a preset detection rate; determining to reduce the cutting speed of the drill bit based on the comparison result that the overheated chip detection rate is greater than the preset detection rate; wherein, a number of speed adjustment coefficients are set based on the comparison result of a first detection rate difference between the overheated chip detection rate and the preset detection rate and a preset difference, so as to reduce the cutting speed based on the number of speed adjustment coefficients.

7. The method for preparing an ultra-low temperature three-section circulator according to claim 6, characterized in that, Under the condition that the roughing process is unqualified, the process of adjusting the feed rate of the finishing drilling stage based on the overheated chip detection rate includes: comparing the overheated chip detection rate with the preset detection rate; determining to reduce the feed rate of the finishing drilling stage based on the comparison result that the overheated chip detection rate is less than or equal to the preset detection rate; wherein, based on the comparison result of the second detection rate difference between the preset detection rate and the overheated chip detection rate and the preset difference, several feed rate adjustment coefficients are set to reduce the feed rate based on the several feed rate adjustment coefficients.

8. The method for preparing an ultra-low temperature three-section circulator according to claim 7, characterized in that, Under the condition of reducing the cutting speed of the drill bit, the process of optimizing the speed adjustment coefficient based on the chip removal efficiency includes: comparing the cutting efficiency with a preset efficiency; determining the speed adjustment coefficient based on the comparison result that the cutting efficiency is less than the preset efficiency; wherein, based on the comparison result of the efficiency difference between the preset efficiency and the cutting efficiency and the preset efficiency difference, several speed optimization coefficients are set to optimize the speed adjustment coefficient based on the several speed optimization coefficients.

9. The method for preparing a cryogenic three-section circulator according to claim 8, characterized in that, The process of optimizing the preset straightness based on the pore diameter uniformity of deep holes includes: comparing the pore diameter uniformity with a preset uniformity; determining the preset straightness to be optimized based on the comparison result that the pore diameter uniformity is greater than the preset uniformity; wherein, based on the comparison result of the uniformity difference between the pore diameter uniformity and the preset uniformity, several straightness optimization coefficients are set to optimize the preset straightness based on the several straightness optimization coefficients.

10. A cryogenic three-segment circulator prepared using the method for preparing a cryogenic three-segment circulator according to any one of claims 1-9, characterized in that, include: A magnetic shielding cover is used to shield a magnetic field; a magnetic field assembly is disposed within the magnetic shielding cover, including a plurality of samarium cobalt permanent magnets for providing a stable bias magnetic field, and iron-nickel alloys symmetrically arranged on the upper and lower sides of the samarium cobalt permanent magnets for optimizing the magnetic field distribution; a signal transmission assembly is disposed in the middle of the magnetic field assembly, including a central conductor for transmitting microwave signals and a wave-absorbing load for absorbing reverse signals; a support assembly includes a cavity for fixing the magnetic field assembly and the signal transmission assembly, and a plurality of ceramic rings for isolating the central conductor from the cavity, wherein the cavity includes an upper cavity and a lower cavity.

Images