Copper-steel composite heat pipe and preparation method thereof

Abstract

The invention provides a copper-steel composite heat pipe and a preparation method thereof, and relates to the technical field of heat pipes, the copper-steel composite heat pipe comprises a steel-copper composite pipe, and the steel-copper composite pipe is composed of a copper inner pipe and a steel outer pipe. An internal copper structure is arranged in the steel-copper composite pipe; the internal copper structure is copper powder or a copper wire mesh. The copper powder is unilateral copper powder or bilateral copper powder or ring copper powder; the copper wire mesh is a copper mesh, or a copper mesh and a copper wire capillary, or a copper wire capillary. The steel outer pipe is made of steel 316L, and the copper inner pipe is made of copper C1020. The copper-steel combined material is used, the cost is saved, and it is guaranteed that materials are saved in the whole heat dissipation field. The double-layer combination of the copper inner pipe (C1020, high heat conduction) and the steel outer pipe (316L, corrosion resistance and high strength) is adopted, the efficient heat conduction of copper is utilized, and the environment erosion resistance and mechanical impact resistance of steel are utilized, so that the heat pipe is adaptive to complex working conditions (such as industrial high-temperature, humid or corrosion risk scenes), and the service life of the heat pipe is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat pipe, in particular to a copper-steel composite heat pipe and a preparation method thereof. BACKGROUND

[0002] Under the background of the rapid increase of power density of modern equipment, the traditional heat dissipation mode has the limitations of low heat transfer efficiency and high energy consumption due to the dependence on metal heat conduction or forced convection, and it is difficult to solve the high heat flux density heat dissipation problem of electronic devices, aerospace equipment and the like. The heat pipe as a high-efficiency heat transfer element breaks through this dilemma.

[0003] The heat pipe currently used is pure copper, copper (shell) + internal capillary (copper powder or copper wire copper mesh), and the cost of shell material accounts for 70-90%. At present, the price of copper for heat pipe is rising continuously, and the cost is rising, which restricts the popular application of heat pipe in medium and low-end equipment. SUMMARY

[0004] The present application provides a copper-steel composite heat pipe and a preparation method thereof to solve the technical problems raised in the background art.

[0005] To solve the above technical problems, the present application discloses a copper-steel composite heat pipe, which comprises a steel-copper composite pipe composed of a copper inner pipe and a steel outer pipe.

[0006] Preferably, an internal copper structure is arranged in the steel-copper composite pipe; the internal copper structure is copper powder or copper wire mesh.

[0007] Preferably, the copper powder is single-sided copper powder, double-sided copper powder or ring copper powder. The copper wire mesh is copper mesh, or copper mesh and copper wire capillary, or copper wire capillary.

[0008] Preferably, the steel outer pipe is made of steel 316L, and the copper inner pipe is made of copper C1020.

[0009] The present application also discloses a preparation method of a copper-steel composite heat pipe for preparing the copper-steel composite heat pipe, comprising the following steps: Step S1: preparation of steel-copper composite pipe and internal copper structure; Step S2: filling the internal copper structure into the steel-copper composite pipe; The preparation of the steel-copper composite pipe comprises the following steps: Step S11: cutting the steel outer pipe and the copper inner pipe to the target size respectively; Step S12: inserting the copper inner pipe into the steel outer pipe to form a double-layer pipe blank; cold-drawing the double-layer pipe blank by a cold-drawing device to realize tight combination by using the interface pressure generated by metal plastic deformation; Step S13: cleaning and testing the steel-copper composite pipe obtained in step S12.

[0010] Preferably, the cold-state reducing device comprises a reducing die and a pipe conveying device, the pipe conveying device being used to push the double-layer pipe blank into the reducing die for reducing or out of the reducing die; The reducing die comprises a die base, a hydraulic cylinder is installed on the die base, a piston rod of the hydraulic cylinder is connected with a die slider, the die slider is embedded in a guide rail of the die base, split forming die segments of a reducing execution module are fixed on the slider, and the slider moves along the guide rail of the die base in a radial direction.

[0011] Preferably, the step S12 comprises: Step S121: obtaining a standard radial feeding speed range and a die standard radial feeding pressure range of the reducing die corresponding to each radial deformation stage of the current batch of pipe blanks; and obtaining a die radial displacement amount-die standard equivalent pressure fitting curve under the corresponding target condition of each radial deformation stage; Step S122: installing a sample pipe blank of the current batch of pipe blanks on the cold-state reducing device, and performing a reducing test under the target condition corresponding to each radial deformation stage obtained in step S121; and obtaining a test deformation parameter of the outer steel pipe and a test deformation parameter of the inner copper pipe during the reducing test; and constructing a radial displacement amount-die actual equivalent pressure fitting curve of each radial deformation stage; Step S123: determining an actual steel-copper covariant coefficient of each radial deformation stage based on step S122; Step S124: obtaining detected die surface key parameters and lubricating medium parameters, and determining a speed correction coefficient and a pressure correction coefficient of each deformation stage based on the die surface key parameters and the lubricating medium parameters; Step S125: determining a pressure difference coefficient based on the radial displacement amount-die actual equivalent pressure fitting curve and the die radial displacement amount-die standard equivalent pressure fitting curve; Step S126: when the pressure difference coefficient is not within the corresponding preset range, prewarning through an alarm; Step S127: when the alarm is not alarmed, determining a target radial feeding speed of each deformation stage of the current batch of pipe blanks and a target radial feeding pressure of each deformation stage based on the speed correction coefficient and the pressure correction coefficient, the pressure difference coefficient, and the steel-copper covariant coefficient.

[0012] Preferably, the corresponding target condition of each radial deformation stage is a median value of a standard radial feeding speed range and a median value of a die standard feeding pressure range of the reducing die corresponding to the radial deformation stage; The die equivalent pressure is an equivalent pressure of a contact surface between the reducing die and the double-layer pipe blank. Further comprising: Step S128: Determine the predicted pressure of the interfacial copper inner tube based on the test deformation parameters of the outer steel tube and the inner copper tube; Step S129: When the predicted pressure of the outer steel pipe of the interface is not within the corresponding preset range, the alarm will also sound.

[0013] Preferably, step S2 includes: Step S21: Fill the steel-copper composite pipe with the copper powder formed by pressing the billet; Step S22: Sinter the copper powder filling the steel-copper composite pipe to initially shape the copper powder and form a sintered semi-finished product. Step S23: Perform tail-shrinking or tail-welding operations on the sintered semi-finished product to trim the end shape; Step S24: Perform a reduction treatment on the semi-finished product obtained in step S23 to remove the surface oxide layer or impurities; Step S25: Perform water injection, first impurity removal, and second impurity removal operations on the reduced semi-finished product in sequence. Water injection fills the internal space, and the material is purified through two impurity removal processes. Step S26: Perform welding, bending, shaping and flattening operations on the semi-finished product after secondary impurity removal.

[0014] Preferably, the corrected target sintering parameters in step S22 are determined based on the following: Step S221: Determine the loose packing correction factor for the current batch of copper powder through loose packing detection; Step S222: Obtain the bulk density of copper powder formed by pressing the current batch of copper powder ingots, and determine the pressing-packing coupling coefficient based on the bulk density of copper powder formed by pressing the current batch of copper powder ingots and the bulk density of copper powder before pressing the current batch of copper powder. And obtain the target sintering parameters of the current type of copper powder under the given bulk density and pressing-packing coupling coefficient, the target sintering parameters including the target sintering temperature and the target holding time; Step S223: Detect the surface characteristic parameters of the inner wall of the copper inner tube, including oxide layer thickness and roughness; and determine the interface bonding state coefficient based on the surface characteristic parameters of the inner wall of the copper inner tube. Step S224: Determine the predicted interface binding strength based on steps S221, S222, and S223; Step S225: Determine the density deviation based on the bulk density of the copper powder formed by pressing the current batch of copper powder and the target density after sintering; Step S226: Correct the target sintering parameters based on the predicted interface bonding strength and density deviation to obtain the corrected target sintering temperature and the corrected target holding time.

[0015] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0016] Compared with the prior art, the present application has the following beneficial effects: The present application uses copper-steel combined material, saves cost, and ensures material saving in the whole heat dissipation field.

[0017] The double-layer composite of copper inner tube (C1020, high thermal conductivity) + steel outer tube (316L, corrosion-resistant and high strength) utilizes the high-efficiency heat conduction of copper and the environmental corrosion resistance and mechanical impact resistance of steel, adapts to complex working conditions (such as industrial high temperature, humidity or corrosion risk scenes), and prolongs the service life of the heat pipe.

[0018] Various internal structures such as copper powder and copper wire mesh are supported. The copper powder can fill fine spaces, and the copper wire mesh (copper mesh, copper mesh + copper wire capillary, etc.) adapts to different heat transfer requirements, widening the application scenarios of the heat pipe (such as small space high-efficiency heat dissipation and electronic equipment with high uniform temperature requirements).

[0019] The cold-state diameter-reducing process makes the double-layer tube blank generate interface pressure through metal plastic deformation, realizing close combination. Compared with traditional connection (such as welding which is prone to thermal stress and gap), this mode eliminates interface gap, improves heat conduction efficiency, reduces thermal resistance, and strengthens the heat transfer performance of the heat pipe.

[0020] The internal copper structure (especially the capillary structure of copper powder and copper wire mesh) can strengthen phase change heat transfer (such as the evaporation-condensation cycle of the working medium), accelerate heat transfer; the heat conduction synergy of the composite tube makes the heat pipe still maintain high efficiency in long-distance and high-power heat dissipation. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the present application, and constitute a part of the specification, together with the embodiments of the present application, to explain the present application, and do not constitute a limitation on the present application. In the drawings: Figure 1 It is a cross-sectional view of the copper inner tube and the steel outer tube of the present application; Figure 2 It is a schematic view of the present application provided with double-sided copper powder; Figure 3 It is a schematic view of the present application provided with single-sided copper powder; Figure 4 It is a schematic view of the present application provided with ring copper powder; Figure 5 It is a schematic view of the present application provided with copper wire capillary; Figure 6 It is a schematic view of the present application provided with copper wire capillary and copper mesh; Figure 7 It is a schematic view of the present application provided with copper mesh.

[0022] Figure 8 It is a preparation flowchart of the copper-steel composite heat pipe of the present application.

[0023] In the figure: 1, copper inner tube; 2, steel outer tube; 3, copper powder; 4, copper wire capillary; 5, copper mesh. DETAILED DESCRIPTION

[0024] The preferred embodiments of the present application will be described below with reference to the drawings, and it should be understood that the preferred embodiments described herein are intended for illustrative purposes only and are not intended to limit the present application.

[0025] In addition, the description such as "first", "second" and the like in the present application is only for the purpose of description, and is not intended to particularly indicate the order or sequence, nor to limit the present application, which is merely to distinguish the components or operations described by the same technical terms, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions and technical features of various embodiments can be combined with each other, but it must be based on the realization of a person skilled in the art, and when the combination of technical solutions appears to be contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor within the protection scope required by the present application.

[0026] The present application provides the following embodiments: Embodiment 1, the present application provides a copper-steel composite heat pipe, as shown in the figure, comprising a steel-copper composite pipe, which is composed of a copper inner tube 1 and a steel outer tube 2. Figures 1-7

[0027] Preferably, an internal copper structure is arranged in the steel-copper composite pipe; the internal copper structure is copper powder 3 or copper wire mesh.

[0028] Preferably, the copper powder 3 is single-sided copper powder or double-sided copper powder or ring copper powder; The copper wire mesh is copper mesh 5, or copper mesh 5 and copper wire capillary 4, or copper wire capillary 4.

[0029] Preferably, the steel outer tube 2 is made of steel 316L, and the copper inner tube 1 is made of copper C1020 (the existing material is copper C1020).

[0030] The present application also discloses a preparation method of a copper-steel composite heat pipe, for preparing the copper-steel composite heat pipe, comprising: Step S1: steel-copper composite pipe preparation, internal copper structure preparation; Step S2: filling the internal copper structure into the steel-copper composite pipe; The steel-copper composite pipe preparation comprises: Step S11: cutting the steel outer tube 2 and the copper inner tube 1 to the target size respectively; ​Step S12: insert the copper inner tube 1 into the steel outer tube 2 to form a double-layer pipe blank; perform cold-diameter-reducing on the double-layer pipe blank through a cold-diameter-reducing device, and realize tight combination by using the interface pressure generated by metal plastic deformation; Step S13: clean and inspect the steel-copper composite pipe obtained in step S12.

[0031] The technical scheme has the beneficial effects that: the copper-steel combined material is used to save cost and ensure material saving in the entire heat dissipation field.

[0032] The double-layer composite of the copper inner tube 1 (C1020, high thermal conductivity) + the steel outer tube 2 (316L, corrosion-resistant and high strength) utilizes the high-efficiency heat conduction of copper and the environmental corrosion resistance and mechanical impact resistance of steel, is suitable for complex working conditions (such as industrial high temperature, humidity or corrosion risk scenes), and prolongs the service life of the heat pipe.

[0033] Various internal structures such as copper powder 3 and copper wire mesh are supported. The copper powder 3 can fill fine spaces, and the copper wire mesh (copper mesh, copper mesh + copper wire capillary 4, etc.) is suitable for different heat transfer requirements, and widens the application scenarios of the heat pipe (such as small space high-efficiency heat dissipation and electronic equipment with high uniform temperature requirements).

[0034] The cold-diameter-reducing process makes the double-layer pipe blank generate interface pressure through metal plastic deformation to realize tight combination. Compared with the traditional connection (such as welding which is easy to produce thermal stress and gap), this mode eliminates the interface gap, improves the heat conduction efficiency, reduces the thermal resistance, and strengthens the heat transfer performance of the heat pipe.

[0035] The internal copper structure (especially the capillary structure of the copper powder 3 and the copper wire mesh) can strengthen the phase change heat transfer (such as the evaporation-condensation cycle of the working medium), accelerate heat transfer; the heat conduction of the composite pipe is coordinated, so that the heat pipe still maintains high efficiency in long-distance and high-power heat dissipation.

[0036] In example 2, based on example 1, The cold-diameter-reducing device includes a diameter-reducing die and a pipe conveying device, and the pipe conveying device is used to push the double-layer pipe blank into the diameter-reducing die for diameter-reducing or push the double-layer pipe blank out of the diameter-reducing die; The diameter-reducing die includes a die seat, a hydraulic oil cylinder is installed on the die seat, a piston rod of the hydraulic oil cylinder is connected with a die sliding block, the die sliding block is embedded in a guide rail of the die seat, and split forming die segments of a diameter-reducing execution module are fixed on the sliding block and move radially along the guide rail of the die seat. This is the prior art, such as CN119870184A.

[0037] Step S12 includes: Step S121: obtain a standard radial feed speed range and a die standard radial feed pressure range of a diameter-reducing die corresponding to each radial deformation stage of the current pipe blank; the die equivalent pressure is the equivalent pressure of the contact surface between the diameter-reducing die and the double-layer pipe blank; and obtaining a mold radial displacement amount-mold standard equivalent pressure fitting curve under the corresponding target condition of each radial deformation stage; Step S122: installing the sample of the current batch of pipe blanks on the cold-state reducing device, and performing the reducing test under the target condition corresponding to each radial deformation stage obtained in step S121; and obtaining the test deformation parameters of the steel outer tube 2 and the test deformation parameters of the copper inner tube 1 during the reducing test; and constructing a radial displacement amount-mold actual equivalent pressure fitting curve of each radial deformation stage; Step S123: determining the actual steel-copper covariant coefficient of each radial deformation stage based on step S122; Step S124: obtaining the detected mold surface key parameters and lubricating medium parameters, and determining the speed correction coefficient and the pressure correction coefficient of each deformation stage based on the mold surface key parameters and the lubricating medium parameters; Step S125: determining the pressure difference coefficient based on the radial displacement amount-mold actual equivalent pressure fitting curve and the mold radial displacement amount-mold standard equivalent pressure fitting curve; Step S126: when the pressure difference coefficient is not within the corresponding preset range, the alarm is also pre-alarmed; Step S127: when the alarm is not alarmed, determining the target radial feed speed of each deformation stage of the current batch of pipe blanks and the target radial feed pressure of each deformation stage based on the speed correction coefficient and the pressure correction coefficient, the pressure difference coefficient, and the steel-copper covariant coefficient.

[0038] Preferably, the corresponding target condition of each radial deformation stage is the median value of the standard radial feed speed range of the reducing die corresponding to the radial deformation stage and the median value of the mold standard feed pressure range; The step S12 further comprises: Step S128: determining the predicted pressure of the interface copper inner tube based on the test deformation parameters of the steel outer tube 2 and the test deformation parameters of the copper inner tube 1; The predicted pressure of the interface copper inner tube 1 is ; is the elastic modulus of the copper inner tube 1; is the tested strain of the steel outer tube 2; is the tested strain of the copper inner tube 1; is the Poisson's ratio of the steel outer tube 2; is the Poisson's ratio of the copper inner tube 1; Step S129: when the predicted pressure of the interface steel outer tube 2 is not within the corresponding preset range, the alarm is also pre-alarmed; The deformation parameters include strain (mainly radial strain); existing detection methods can be used to determine (such as strain gauges); And the copper inner tube 1 strain determines that the copper inner tube is in its own specific deformation stage (elastic deformation stage, plastic deformation stage), and the steel outer tube 2 strain determines that the steel outer tube is in its own specific deformation stage (elastic deformation stage, plastic deformation stage); First, based on the copper inner tube 1 test actual strain to determine which radial deformation stage it belongs to; Steel copper covariant coefficient = first strain weight × (copper inner tube 1 test actual strain ÷ the theoretical strain of copper inner tube 1 corresponding to the current radial feeding time) + (steel outer tube 2 test actual strain ÷ the theoretical strain of steel outer tube 2 corresponding to the current radial feeding time) × second strain weight; The first strain weight, the first strain weight: need to combine specific test + application scene, determine through data fitting, demand adaptation, such as: Test calibration: under standard working conditions (fixed temperature, pressure, radial feeding, Etc.), let the copper inner tube and the steel outer tube deform cooperatively, collect multiple groups of "copper inner tube actual strain, steel outer tube actual strain, theoretical strain and covariant effect" data, use regression analysis, optimization algorithm (such as least square method) fitting, find the weight combination that makes the covariant coefficient accurately reflect the degree of cooperation of the two.

[0039] Scene adaptation: according to the process demand side (such as paying more attention to the deformation stability of the copper inner tube, increasing the first strain weight; if the steel outer tube is the key constraint of bearing, increase the second strain weight), through trial and error, compare the matching degree of covariant coefficient and actual deformation law under different weights, determine the adaptive value.

[0040] Each radial deformation stage is determined under the corresponding target condition time-copper inner tube 1 standard strain fitting curve and steel outer tube 2 standard strain fitting curve; based on the test process of pipe blank quality standard forming quality standard; Step S124: obtain the detected mold surface key parameters and lubricating medium parameters, determine the speed correction coefficient and pressure correction coefficient of each deformation stage based on the mold surface key parameters and lubricating medium parameters; wherein the mold surface key parameters include: the roughness of the mold extrusion surface, the friction coefficient; the lubricating medium parameters include the viscosity of the lubricating medium; ; ; The speed correction coefficient for the current deformation stage is; The pressure correction coefficient for the current deformation stage is; The actual lubricating medium viscosity and the standard lubricating medium viscosity are respectively; The actual mold extrusion surface roughness and the standard mold extrusion surface roughness are respectively; respectively, are the friction coefficients of the actual die extrusion surface and the standard die extrusion surface; respectively, are the viscosity of the lubricating medium, the roughness of the die extrusion surface, and the friction coefficient of the die extrusion surface corresponding to the die radial feed speed correction adjustment coefficient of the current deformation stage; respectively, are the viscosity of the lubricating medium, the roughness of the die extrusion surface, and the friction coefficient of the die extrusion surface corresponding to the die radial feed pressure correction adjustment coefficient of the current deformation stage; the above adjustment coefficients are fitted through orthogonal test / simulation (changing a single parameter, observing the ideal speed / pressure theoretical change, and deducing the coefficient); Current tube blank: refers to the type of the current batch of tube blanks (due to different tube blank materials, initial sizes, wall thicknesses, etc., the reduction parameter difference is large, and targeted matching is needed).

[0041] The same tube blank: the same material: the same grade, chemical composition, and mechanical properties (yield strength fluctuation ≤5%) of the steel outer tube and the copper inner tube, and the same interface state (bonding method, roughness Ra deviation ≤0.2 μm); Uniform structure: the same initial outer diameter (within the same tube diameter range), wall thickness (within the same wall thickness range), fitting method, and tube diameter ratio (within the same tube diameter ratio); the same state: the same pretreatment process (such as sandblasting, lubrication).

[0042] Radial deformation stage: the tube blank is gradually contracted from the initial double-layer state through die extrusion during reduction, and the stage is divided according to the deformation degree / mechanical characteristics (such as elastic deformation synchronization stage, copper inner tube 1 plasticity first stage, steel outer tube 2 plasticity cooperation stage, double tube plasticity stable stage, and pressure maintaining and shaping stage).

[0043] Standard radial feed speed range: the speed interval of the die radial extrusion of the tube blank (such as 1-5 mm / s), which affects the reduction efficiency and the uniformity of the tube blank deformation, and needs to be tested to determine the reasonable range.

[0044] Die standard radial feed pressure range: the equivalent pressure interval of the contact surface between the die and the tube blank (such as 50-200 MPa), which reflects the extrusion degree of the die on the tube blank and is related to the interface bonding strength.

[0045] Die radial displacement amount-die equivalent pressure fitting curve: the relationship curve between the die radial movement distance (displacement amount) and the corresponding equivalent pressure during reduction, which is used for real-time monitoring and adjusting process parameters to ensure the reduction quality.

[0046] “Standard radial feed speed range + die standard radial feed pressure range” obtains the test design typical tube blank (covers different materials, initial sizes; The test is carried out on a variable parameter pipe reducing test bench (adjustable mold feeding speed, pressure) to determine the standard radial feeding speed range. The other parameters (such as mold material, lubrication condition) are fixed, and the mold radial feeding speed is changed in sequence (such as 0.5 mm / s step, from 0.5 to 6 mm / s), and the pipe blank mass after reduction (such as interface bonding force, roundness, wall thickness uniformity) is recorded. Data analysis selects the feeding speed interval of the pipe blank mass meeting the standard as the standard radial feeding speed range. The pressure of the mold and pipe blank contact surface during reduction is synchronously collected (by embedding a pressure sensor in the mold), and the pressure interval when the mass meets the standard is counted as the standard radial feeding pressure range of the mold. Repeat the test for different pipe blanks (material, size change), and summarize the corresponding relationship of "pipe blank type-radial deformation stage-speed / pressure range".

[0047] The "mold radial displacement amount-mold standard equivalent pressure fitting curve" (mass meeting the standard) is obtained by synchronously collecting the reduction test. The mold radial displacement amount (the distance moved by the mold during extrusion) is recorded in real time by a displacement sensor (such as a laser displacement meter), and the corresponding pressure sensor data (equivalent pressure) is synchronously collected. For each radial deformation stage (which needs to be divided into stages in advance through mechanical simulation / test), a plurality of "displacement-pressure" data is collected under the "standard radial feeding speed range median value" (such as the speed range 1-5 mm / s, the median value is 3 mm / s). Curve fitting is performed using data analysis software (such as Origin, MATLAB) to fit the "displacement-pressure" data of the same radial deformation stage (such as linear fitting, polynomial fitting). The fitting curve of this stage is obtained.

[0048] The current equivalent pressure is the average detection value of all pressure sensors arranged radially and axially by the current mold; Step S125: determining the pressure difference coefficient based on the radial displacement amount-mold actual equivalent pressure fitting curve and the mold radial displacement amount-mold standard equivalent pressure fitting curve; specifically: ; Wherein, H is the pressure difference coefficient; M is the total number of selected key displacement amounts; is the target standard equivalent pressure corresponding to the selected ith key displacement amount in the mold radial displacement amount-mold standard equivalent pressure fitting curve; is the mold actual equivalent pressure corresponding to the selected ith key displacement amount in the radial displacement amount-mold actual equivalent pressure fitting curve; the key displacement amount is a radial displacement node that has a decisive influence on the process / quality / deformation; Determine the target radial feeding speed of each deformation stage and the target radial feeding pressure of each deformation stage of the current batch of pipe blanks based on the speed correction coefficient and the pressure correction coefficient, the pressure difference coefficient, and the steel-copper covariant coefficient. Specifically: ; is the target radial feed speed of the current deformation stage; is the speed correction coefficient of the current deformation stage; is the pressure difference coefficient of the current deformation stage; H is the steel-copper covariant coefficient of the current deformation stage; is the radial feed speed adjustment coefficient corresponding to the pressure difference coefficient of the current deformation stage, respectively, and the radial feed speed adjustment coefficient corresponding to the steel-copper covariant coefficient of the current deformation stage; is the standard radial feed speed range median of the current deformation stage; ; is the mold standard feed pressure range median of the current deformation stage; is the target radial feed pressure of the current deformation stage; is the radial feed pressure adjustment coefficient corresponding to the pressure difference coefficient of the current deformation stage, respectively, and the radial feed pressure adjustment coefficient corresponding to the steel-copper covariant coefficient of the current deformation stage; The above adjustment coefficients can be determined by orthogonal test / simulation fitting, and the values are greater than 0 and less than 1; The beneficial effects of the above technical solutions are: Through the "standard range + correction coefficient" model, the mold feed speed, pressure and other parameters are bound with the pipe blank deformation stage depth. For example, in the "elastic deformation synchronization stage", the speed is strictly controlled to avoid deformation mismatch of the copper inner tube / steel outer tube due to too fast feeding; in the "plasticity coordination stage", the pressure is dynamically adjusted to ensure uniform interface bonding force, thereby reducing the pipe blank roundness deviation, wall thickness unevenness and other quality problems from the root. Full-stage quality monitoring: "pressure difference coefficient" real-time early warning (S126, S129) of key displacement points, once the actual pressure deviates from the standard curve, an alarm is triggered immediately to avoid batch rejection. When the extrusion surface of the reducing die is worn, the system can intervene in advance to ensure the pipe blank forming quality.

[0049] Based on the correction coefficient of "lubricating medium, mold roughness", the production environment changes are dynamically adapted. For example, when the viscosity of the lubricating medium decreases, the feeding speed is automatically adjusted to compensate for the lack of lubrication, without the need for manual trial and error, thereby shortening the process debugging time and improving the reducing efficiency. Quantification of cooperative deformation: the "steel-copper covariant coefficient" accurately captures the deformation coordination of the double-layer pipe blank, avoiding interface peeling, wrinkling and other defects caused by asynchronous deformation of copper / steel. This reduces the cost of subsequent repair or rejection, especially for high-precision composite pipes (such as nuclear power and aviation pipes).

[0050] Through "radial deformation stage division" (elastic synchronization, plastic cooperation, etc.), the complex reducing process is disassembled into standardized sub-stages, and each stage matches independent parameter range and correction logic. Whether it is a thin-walled pipe, a thick-walled pipe, or a copper-steel material ratio change, only the stage division and reference parameters need to be adjusted to quickly adapt to new scenarios. Knowledge sedimentation and reuse: "standard feed speed / pressure range" "mold-displacement-pressure fitting curve" is deposited as a process knowledge base through testing, which can be directly reused by new production lines or new employees, reducing the technical threshold and accelerating process replication and iteration.

[0051] From "test deformation parameters" to "correction coefficient calculation", and then to "automatic parameter adjustment", all links are driven by actual measurement data, getting rid of experience dependence. Long-term accumulated process data can be further used for machine learning modeling to predict potential quality risks (such as predicting the probability of plastic deformation stage cracking through historical strain data), and to upgrade the process to "predictive maintenance-regulation".

[0052] In embodiment 3, on the basis of embodiment 1 or 2, step S2 comprises: Step S21: filling the copper powder 3 formed by the compact into the steel-copper composite pipe; Step S22: sintering the copper powder 3 filled in the steel-copper composite pipe to preliminarily form the copper powder 3, to form a sintered semi-finished product; Step S23: performing a tail shrinking or tail welding operation on the sintered semi-finished product to trim the end shape; Step S24: performing a reduction treatment on the semi-finished product obtained in step S23 to remove the surface oxide layer or impurities; Step S25: sequentially performing water injection, primary impurity removal, and secondary impurity removal operations on the reduced semi-finished product, filling the internal space by water injection, and purifying the material through two impurity removal processes; Step S26: performing a head welding, bending, shaping, and flattening operation on the semi-finished product after the secondary impurity removal.

[0053] The beneficial effects of the above technical solutions are: The sintering process (step S22) causes diffusion and fusion between copper powder particles, and preliminarily forms a continuous copper matrix.

[0054] The tail shrinking / welding (step S23) trims the end part to avoid shape defects (such as bulges and gaps) caused by filling and sintering, ensures the structural integrity of the end part of the composite pipe, and improves the adaptability of subsequent connection and use.

[0055] The reduction treatment (step S24) specifically removes the surface oxide layer (such as copper oxide and iron oxide) and impurities generated during sintering and processing, restores the cleanliness of the material, and avoids the influence of the oxide layer on the copper-steel interfacial bonding force and reduces the electrical conductivity / thermal conductivity.

[0056] Water injection, impurity removal (step S25) combines physical filling with chemical / physical impurity removal to deeply purify the internal space and remove fine impurities (such as residual copper powder particles, sintering byproducts), thereby reducing the interference of "impurity-type defects" with the mechanical and physical properties of the composite pipe.

[0057] Sintering preliminarily shapes the copper powder and gives the copper material a certain strength; the tailoring / reducing, reducing, and impurity removal processes are coordinated to eliminate internal stress concentration and microscopic defects (such as pores and microcracks), thereby gradually improving the overall strength and toughness of the composite pipe and adapting to subsequent bending (step S26) and other shaping requirements, thereby avoiding cracking during processing.

[0058] The copper-steel interface is combined more closely after sintering and reduction, and the stress performance is enhanced, so that the copper-steel is not easy to peel off under tensile and torsional working conditions, thereby ensuring the mechanical reliability of the composite pipe.

[0059] The internal copper structure (especially the capillary structure of the copper powder 3 and the copper wire mesh) can strengthen phase change heat transfer (such as the evaporation-condensation cycle of the working medium) and accelerate heat transfer; the heat conduction of the composite pipe is coordinated, so that the heat pipe still maintains high efficiency in long-distance and high-power heat dissipation.

[0060] In example 4, on the basis of example 3, the corrected target sintering parameters in step S22 are determined based on the following: Step S221: Determine the loose packing correction coefficient of the current batch of copper powder 3 by loose packing detection of the current batch of copper powder 3; Step S222: Obtain the packing density of the copper powder 3 formed by the green compact of the current batch of copper powder 3, and determine the pressing-packing coupling coefficient based on the packing density of the copper powder 3 formed by the green compact of the current batch of copper powder 3 and the packing density of the current batch of copper powder 3 before pressing; and obtain the target sintering parameters under the packing density of the copper powder 3 formed by the green compact of the current batch of copper powder 3 and the pressing-packing coupling coefficient, the target sintering parameters including the target sintering temperature and the target holding time; Step S223: Detect the surface characteristic parameters of the inner wall of the copper inner tube 1, including the thickness of the oxide layer and the roughness, and determine the interface bonding state coefficient based on the surface characteristic parameters of the inner wall of the copper inner tube 1; Step S224: Determine the predicted interface bonding strength based on steps S221, S222, and S223; Step S225: Determine the density deviation based on the packing density of the copper powder 3 formed by the green compact of the current batch of copper powder 3 and the target density after sintering; the density deviation = the target density of the current batch of copper powder 3 after sintering - the packing density of the copper powder 3 formed by the green compact of the current batch of copper powder 3; Step S226: Correct the target sintering parameters based on the predicted interface bonding strength and the density deviation, to obtain the corrected target sintering temperature and the corrected target holding time.

[0061] The target sintering temperature and the corrected target holding time are controlled when the current batch of copper powder 3 is sintered in batch; The current batch of copper powder 3 is loose and accumulated to correct the coefficient; Specifically, the actual loose and accumulated density of the current batch of copper powder 3 when determining the target sintering parameters of the current batch of copper powder 3; The current batch of copper powder 3 is the current batch of copper powder 3; The determination of "the same kind of copper powder" needs to be unified from three aspects: Composition: main component (copper and alloy) deviation ≤0.5%, impurity fluctuation ≤0.1%; Physical properties: particle size (D10 / D50 / D90), shape ratio, specific surface area deviation ≤5%-10%; Process state: pretreatment (ball milling, annealing, etc.), consistent storage temperature and humidity / time.

[0062] The pressing-accumulation coupling coefficient = the accumulation density of the copper powder 3 formed by the green compact of the current batch of copper powder 3 ÷ the accumulation density of the current batch of copper powder 3 before pressing; The target sintering parameters of the current batch of copper powder 3 under the accumulation density and the pressing-accumulation coupling coefficient (qualified) are obtained, including the target sintering temperature and the target holding time; Specifically: Through a large number of matching tests of "pressing-accumulation coupling coefficient + green compact accumulation density" and "target sintering parameters" in advance, a mapping relationship library (which can be understood as a "process-parameter table") is constructed. In actual production, according to the "green compact accumulation density, pressing-accumulation coupling coefficient" obtained by testing the current batch of copper powder, the corresponding target sintering temperature and holding time are matched directly from the library, without complex formula calculation.

[0063] The reference loose and accumulated density is: Under "standardized test conditions" (standard test instruments and standard environmental temperature and humidity range), the loose and accumulated density test is carried out on "the same kind of copper powder" (the composition, physical properties and pretreatment process are completely consistent), and the "ideal reference value" obtained is used to judge whether the loose state of the current produced copper powder is normal. A copper powder in a mapping relationship library is in a corresponding reference parameter (reference loose and accumulated density, reference interface bonding strength, reference pressing-accumulation coupling coefficient); Step S223: detecting the inner wall surface characteristic parameters of the copper inner tube 1, including the thickness of the oxide layer and the roughness; and determining the interface bonding state coefficient based on the inner wall surface characteristic parameters of the copper inner tube 1; Specifically: ; ; The interface bonding state coefficient W= × oxidation correction weight + R × roughness correction weight; the oxide layer thickness detected in step S223; the oxide layer thickness near the thickness; the roughness detected in step S223; the optimal roughness in the allowable roughness range of the copper inner tube 1 inner wall surface combined with copper powder 3; the worst roughness in the allowable roughness range of the copper inner tube 1 inner wall surface combined with copper powder 3; both of the above weights are greater than 0 and less than 1, and the sum of the two is 1, which is adjusted according to the process emphasis.

[0064] Step S224: determining the predicted interface bonding strength based on steps S221, S222, and S223 ; when the predicted interface bonding strength is not within the corresponding preset range, a warning is given; ; wherein, the reference interface bonding strength; the current batch of copper powder 3 loose packing correction coefficient; the current batch of copper powder 3 pressing-packing coupling coefficient; the reference pressing-packing coupling coefficient; the first, second, and third correction indices, respectively; The correction index is the "contribution weight of each influencing factor to the interface bonding strength", which needs to be determined through orthogonal test + regression analysis, and reflects the influence degree of loose packing correction, pressing-packing coupling, and interface state on the strength. Each correction index can be greater than 0 and less than 1; Step S225: determining the density deviation based on the packing density of the copper powder 3 formed by the current batch of copper powder 3 and the target density after sintering; density deviation = target density of the current batch of copper powder 3 after sintering - packing density of the copper powder 3 formed by the current batch of copper powder 3; Step S226: correcting the target sintering parameters based on the predicted interface bonding strength and the density deviation, to obtain the corrected target sintering temperature and the corrected target holding time.

[0065] corrected target sintering temperature = target sintering temperature + temperature compensation coefficient one × (target interface bonding strength - predicted interface bonding strength) + density deviation × temperature compensation coefficient two; temperature compensation coefficient one unit is ℃ / Pa; time compensation coefficient one unit is min / Pa; temperature compensation coefficient two unit is ℃ / density; time compensation coefficient two unit is min / density; corrected target sintering temperature = target sintering temperature + temperature compensation coefficient one × (target interface bonding strength - predicted interface bonding strength) + density deviation × temperature compensation coefficient two; temperature compensation coefficient one unit is ℃ / Pa; time compensation coefficient one unit is min / Pa; temperature compensation coefficient two unit is ℃ / density; time compensation coefficient two unit is min / density; The compensation coefficient is a "process deviation and sintering parameter adjustment amount corresponding relationship", which is determined by orthogonal test + regression analysis, and reflects the influence weight of "interface bonding strength deviation and density deviation" on sintering temperature / time.

[0066] The beneficial effects of the above technical solutions are: The scheme covers the whole process of "copper powder loose packing - pressing - interface detection - strength prediction - sintering parameter correction - batch production", and through the following: loose packing correction: quantifying the influence of the initial packing state of copper powder on the subsequent process, to avoid quality fluctuations caused by loose packing differences. Pressing-accumulation coupling: relating the pressing process to the density of the compact, to ensure the consistency of the green body quality before sintering. Interface state detection: focusing on the key characteristics (oxidation, roughness) of the inner wall of the copper inner tube, to accurately control the quality of the copper-steel composite interface. Strength prediction and parameter correction: based on a multi-factor coupled model, dynamically adjusting the sintering parameters to realize a closed loop of "quality prediction - process compensation", solving the pain points of traditional processes such as "experience dominance and poor adaptability".

[0067] Mapping relationship library construction: through the matching test of "pressing-accumulation coupling coefficient + compact density" and "sintering parameters", complex process parameters are converted into "table lookup" operation, which can be quickly adapted in production site, reducing the dependence on high-skilled personnel.

[0068] Correction index and compensation coefficient: through orthogonal test + regression analysis, the influence weight of each factor is quantified, which not only retains the process flexibility (weight can be adjusted), but also ensures the scientificity of the parameters, adapting to the differences in equipment and raw materials of different enterprises.

[0069] Quality early warning mechanism: set a preset range for the interface bonding strength to warn in advance and intercept unqualified products, reducing production waste.

[0070] For the core quality demands of steel-copper composite pipe (interface bonding strength, density), the interface bonding strength model integrates "loose packing, pressing, interface state" three factors, accurately corresponding to the interface quality control requirements of "copper inner tube - copper powder - steel outer tube" of composite pipe. The density deviation correction directly relates to the compact and sintering target, ensuring the mechanical properties (such as crushing strength, burst pressure) of the composite pipe, and avoiding the risk of failure caused by insufficient density.

[0071] Interface bonding and density guarantee: accurate control to improve the interface bonding strength of steel-copper composite pipe by 10%-15%, the density compliance rate is over 98%, the core performance indicators such as product burst pressure and crushing strength are stable and better than industry standards, helping to break through in high-end markets (such as high-pressure fluid transportation, precision machinery).

[0072] Customized adaptation capability: By adjusting the correction index weight (such as focusing on interface strength or density), the performance requirements of different customers for the composite pipe (such as building pipes focusing on cost and military pipes focusing on strength) can be quickly adapted, expanding the market application scenarios.

[0073] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A copper-steel composite heat pipe, characterized in that: It includes a steel-copper composite pipe, which consists of a copper inner pipe (1) and a steel outer pipe (2).

2. The copper-steel composite heat pipe according to claim 1, characterized in that: The steel-copper composite pipe is provided with an internal copper structure; the internal copper structure is copper powder (3) or copper wire mesh.

3. The copper-steel composite heat pipe according to claim 2, characterized in that: The copper powder (3) is single-sided copper powder, double-sided copper powder, or circular copper powder; The copper wire mesh type is copper mesh (5), or copper mesh (5) and copper wire capillary (4), or copper wire capillary (4).

4. A copper-steel composite heat pipe according to claim 1, characterized in that: The outer steel tube (2) is made of 316L steel, and the inner copper tube (1) is made of C1020 copper.

5. A method for preparing a copper-steel composite heat pipe, used to prepare a copper-steel composite heat pipe as described in any one of claims 1-4, characterized in that, include: Step S1: Preparation of steel-copper composite pipe and internal copper structure; Step S2: Fill the steel-copper composite pipe with the internal copper structure; The preparation of steel-copper composite pipes includes: Step S11: Cut the outer steel tube (2) and the inner copper tube (1) to the target size respectively; Step S12: Insert the copper inner tube (1) into the steel outer tube (2) to form a double-layer tube blank; use a cold-state diameter reduction device to perform cold-state diameter reduction on the double-layer tube blank, and use the interface pressure generated by the plastic deformation of the metal to achieve a tight bond; Step S13: Clean and inspect the steel-copper composite pipe obtained in step S12.

6. The method for preparing a copper-steel composite heat pipe according to claim 5, characterized in that, The cold-state tube reduction device includes a tube reduction die and a tube conveying device, wherein the tube conveying device is used to push the double-layer tube blank into the tube reduction die for tube reduction or out of the tube reduction die. The diameter reduction mold includes a mold base, a hydraulic cylinder is mounted on the mold base, the piston rod of the hydraulic cylinder is connected to the mold slider, the mold slider is embedded in the mold base guide rail, and the split forming mold piece of the diameter reduction execution module is fixed on the slider and moves radially along the mold base guide rail with the mold slider.

7. The method for preparing a copper-steel composite heat pipe according to claim 6, characterized in that, Step S12 includes: Step S121: Obtain the standard radial feed speed range and standard radial feed pressure range of the die for each radial deformation stage of the current tube blank; And obtain the mold radial displacement-mold standard equivalent pressure fitting curve for each radial deformation stage under the corresponding target conditions; Step S122: Install the sample of the current batch of tube blanks into the cold shrinkage device, and perform shrinkage test under the target conditions corresponding to each radial deformation stage obtained in step S121; And obtain the test deformation parameters of the steel outer tube (2) and the copper inner tube (1) during the diameter reduction test; and construct the radial displacement-actual equivalent pressure fitting curve of the mold for each radial deformation stage; Step S123: Determine the actual steel-copper covariance coefficient for each radial deformation stage based on step S122; Step S124: Obtain the key parameters of the mold surface and the lubrication medium parameters, and determine the speed correction coefficient and pressure correction coefficient for each deformation stage based on the key parameters of the mold surface and the lubrication medium parameters; Step S125: Determine the pressure difference coefficient based on the fitting curve of radial displacement - actual equivalent pressure of the mold and the fitting curve of radial displacement - standard equivalent pressure of the mold; Step S126: When the pressure difference coefficient is not within the corresponding preset range, an alarm is triggered to issue a warning; Step S127: When the alarm does not sound, determine the target radial feed rate and target radial feed pressure for each deformation stage of the current batch of billet based on the speed correction coefficient, pressure correction coefficient, pressure difference coefficient, and steel-copper covariance coefficient.

8. The method for preparing a copper-steel composite heat pipe according to claim 7, characterized in that, Each radial deformation stage is defined by the median of the standard radial feed speed range and the median of the standard feed pressure range for the corresponding radial deformation stage die. The equivalent pressure of the die is the equivalent pressure at the contact surface between the reducing die and the double-layer tube blank. Also includes: Step S128: Determine the predicted pressure of the interface copper inner tube (1) based on the test deformation parameters of the steel outer tube (2) and the test deformation parameters of the copper inner tube (1); Step S129: When the predicted pressure of the interface steel outer tube (2) is not within the corresponding preset range, the alarm will also be triggered.

9. The method for preparing a copper-steel composite heat pipe according to claim 5, characterized in that, Step S2 includes: Step S21: Fill the steel-copper composite tube with the copper powder (3) formed by pressing the billet; Step S22: Sinter the copper powder (3) filling the steel-copper composite pipe to make the copper powder (3) initially formed and form a sintered semi-finished product; Step S23: Perform tail-shrinking or tail-welding operations on the sintered semi-finished product to trim the end shape; Step S24: Perform a reduction treatment on the semi-finished product obtained in step S23 to remove the surface oxide layer or impurities; Step S25: Perform water injection, first impurity removal, and second impurity removal operations on the reduced semi-finished product in sequence. Water injection fills the internal space, and the material is purified through two impurity removal processes. Step S26: Perform welding, bending, shaping and flattening operations on the semi-finished product after secondary impurity removal.

10. The method for preparing a copper-steel composite heat pipe according to claim 9, characterized in that, The corrected target sintering parameters in step S22 are determined based on the following: Step S221: The loose packing correction factor for the current batch of copper powder (3) is determined by loose packing detection; Step S222: Obtain the bulk density of copper powder (3) formed by pressing the current batch of copper powder (3) into a blank, and determine the pressing-packing coupling coefficient based on the bulk density of copper powder (3) formed by pressing the current batch of copper powder (3) into a blank and the bulk density of copper powder (3) before pressing the current batch of copper powder (3); And obtain the target sintering parameters of the current copper powder (3) under the said packing density and pressing-packing coupling coefficient, the target sintering parameters including the target sintering temperature and the target holding time; Step S223: Detect the surface characteristic parameters of the inner wall of the copper inner tube (1): including oxide layer thickness and roughness; and determine the interface bonding state coefficient based on the surface characteristic parameters of the inner wall of the copper inner tube (1); Step S224: Determine the predicted interface binding strength based on steps S221, S222, and S223; Step S225: Determine the density deviation based on the bulk density of the copper powder (3) formed by pressing the current batch of copper powder (3) into a compact and the target density after sintering; Step S226: Correct the target sintering parameters based on the predicted interface bonding strength and density deviation to obtain the corrected target sintering temperature and the corrected target holding time.

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