A short-process preparation method and preparation equipment of high-performance precise resistance alloy extremely thin foil

Abstract

The application discloses a short-process preparation method of high-performance precise resistance alloy extremely thin foil and a preparation device thereof, and belongs to the technical field of non-ferrous metal material processing. The method comprises the following steps: placing constantan, Evan, Kama and other alloy raw materials in a cold crucible to perform suspension smelting, so that pure and uniform alloy melt is obtained; inert gas is filled into a smelting chamber in a sealed environment, the alloy melt is pressed out through a slit nozzle at the bottom of the crucible by using the gas pressure, a melt jet is formed, the melt jet is sprayed to the surface of a high-speed rotating cooling roller, and a crystalline thin strip with a thickness of 10-60 microns is formed by cooling and solidification; and precise cold rolling is performed to obtain constantan foil with a thickness of 3-10 microns. According to the application, high purification of the melt is realized through suspension smelting, the melt is accurately extruded through gas pressure driving and a slit nozzle, and a thin strip blank with uniform structure is obtained through rapid solidification, so that the process flow is significantly shortened, the material utilization rate and product quality are improved, and the application is suitable for the preparation of extremely thin foil in the fields of precise resistance and strain gauge.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal material processing technology, specifically a short-process preparation method and equipment for high-performance precision resistance alloy ultra-thin foil. Background Technology

[0002] Constantan, Evan, and Karma alloys are widely used as core functional materials for precision resistors, strain gauges, and heating elements due to their stable moderate resistivity and low temperature coefficient of resistance. With the miniaturization and high precision of modern electronic devices, the market demand for ultra-thin constantan foils with thicknesses less than 10 micrometers, or even down to 5 micrometers, is becoming increasingly urgent.

[0003] Currently, the industrial production of constantan, Evan, and Karma foils mainly employs the traditional long-process technology of "vacuum induction melting → casting into ingots → hot rolling → multiple cold rolling and intermediate annealing". This process has the following inherent defects:

[0004] (1) Limited metallurgical quality: Traditional crucible smelting is prone to introducing impurities such as carbon and oxygen, and the casting process is prone to component segregation and macroscopic inclusions, making it difficult to meet the stringent requirements of precision resistance alloys for material purity and consistency.

[0005] (2) Low yield and efficiency: Rolling from a cast ingot tens of millimeters thick to an extremely thin foil requires dozens of cold rolling passes and multiple intermediate annealing processes. The process is lengthy, work hardening is severe, and the risk of edge cracking is high, resulting in low yield and high manufacturing costs.

[0006] (3) Poor adaptability of billet: Although the existing rapid solidification casting technology can be used to prepare thin strips, it mostly adopts tilting casting, which has poor flow control accuracy and makes it difficult to obtain high-quality crystalline thin strip billets with uniform width and consistent thickness (such as 20 micrometers), which cannot provide ideal precursors for subsequent precision rolling.

[0007] Existing patent documents, such as CN117505885A, disclose a spray forming device based on suspension melting, but these mainly focus on the preparation of powder or granular blanks and do not involve the continuous forming of foil materials. Other documents involve the structural design of water-cooled copper crucibles, but none of them have solved the technical problem of directly preparing ultrathin crystalline ribbons from high-purity melts. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and propose a short-process preparation method and equipment for high-performance precision resistance alloy ultrathin foil, aiming to solve the problem that traditional processes cannot efficiently and effectively prepare ultrathin, high-purity precision resistance alloy foil.

[0009] To achieve the above objectives, the technical solution specifically adopted by the present invention is as follows: A short-process preparation method for high-performance precision resistance alloy ultrathin foil includes the following steps: Step 1, Material Preparation and Suspension Melting: Weigh the raw materials according to the target composition ratio of the precision resistance alloy. The raw materials include Cu, Ni, Mn, Cr, etc. Place them in a cold crucible suspension melting furnace and carry out suspension melting under vacuum or inert gas protection. The electromagnetic force generated by the high-frequency electromagnetic field keeps the alloy melt in a non-contact state with the wall of the cold crucible until the alloy is completely melted and fully homogenized to obtain a pure and uniform alloy melt.

[0010] Step 2, Gas-driven extrusion: Seal the melting chamber and fill it with high-purity inert gas. By precisely controlling the gas pressure, the alloy melt is stably extruded from a specially designed slit nozzle located at the bottom of the crucible, forming a continuous sheet-like melt jet.

[0011] Step 3, Rapid solidification into a strip: The extruded melt jet is directly sprayed onto the surface of a high-speed rotating cooling roller that is internally supplied with a cooling medium, at a speed of 10... 2 -10 6 The rapid solidification at a cooling rate of K / s results in a continuous crystalline ribbon with a thickness of 10-60 micrometers.

[0012] Step 4, winding and post-processing: The crystalline strip is peeled off from the cooling roller and wound up. According to the final product requirements, the strip is subjected to precision cold rolling and / or heat treatment to obtain constantan finished foil of the target thickness.

[0013] As a preferred embodiment of the present invention, the constantan alloy described in step 1 contains, by mass percentage, 39%-49% Ni, 1%-5% Mn, and the balance being Cu.

[0014] In a preferred embodiment of the present invention, the slit width of the specially designed slit nozzle in step 2 is 0.1-2.0 mm, and the length is 50-160 mm. The pressure control range of the inert gas is 10-200 kPa. By adjusting the gas pressure, the melt outflow rate is controlled, thereby controlling the thickness of the thin strip.

[0015] As a preferred embodiment of the present invention, the cooling roller in step 3 is a copper roller or a roller that can be automatically temperature controlled and has good wettability with the interface of the smelted alloy, with a surface linear velocity of 4-60 m / s and a cooling medium flow channel inside.

[0016] As a preferred embodiment of the present invention, the precision cold rolling in step 4 rolls a 10-60 micrometer crystalline strip to 3-10 micrometers, with 2-4 rolling passes.

[0017] In a second aspect, the present invention provides a constantan ultrathin foil preparation apparatus for implementing the above method, comprising: A suspended melting chamber with a cold crucible; A slit nozzle is provided at the bottom of the cold crucible; A controllable inert gas pressurization system connected to the melting chamber; Rotary cooling rollers and thin strip collecting devices are installed below or to the side of the melting chamber.

[0018] As a preferred embodiment of the present invention, the slit width of the slit nozzle is adjustable to adapt to the production of thin strips with different thickness requirements.

[0019] As a preferred embodiment of the present invention, the device further includes a thin strip guide device and a tension control device located on one side of the cooling roller to ensure smooth winding of the thin strip.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) Fundamental improvement in material quality The cold crucible suspension melting technology achieves contactless purification of the melt, completely eliminating crucible material contamination and efficiently removing gases and inclusions from the alloy. The segmented structure of the cold crucible allows magnetic lines of force to penetrate, creating strong electromagnetic stirring in the melt. This ensures a macroscopically uniform distribution of easily segregating elements such as Ni and Mn, providing a high-quality melt source for high-performance precision resistance alloy foils. The fully suspended melting process also avoids shell formation and improves the uniformity of melting temperature.

[0021] (2) Revolutionary shortening of the process flow This innovative technology integrates suspension melting, pneumatic drive, and rapid solidification, directly skipping the traditional ingot casting and hot rolling processes to obtain near-net-shape strips of 20 micrometers in one step, achieving a "short-process" manufacturing from melt to strip billet. Compared with traditional processes, the process is shortened by more than 60% and energy consumption is reduced by more than 40%.

[0022] (3) The quality of the thin strip is precisely controllable By utilizing inert gas pressure drive and a bottom-slit nozzle to replace the traditional tilting pouring method, and through coordinated control of air pressure and roller speed, the melt flow rate and solidification process are precisely regulated to stably produce crystalline ribbons with uniform width, consistent thickness, and smooth surface. The bottom nozzle design draws on the flow channel control concept of directional solidification technology to ensure the stability of the melt jet.

[0023] (4) High-quality billets facilitate ultimate rolling The resulting 15-30 micrometer thin strips exhibit uniform microstructure, fine grains, and excellent plasticity, making them ideal billets for precision rolling. The rapid solidification process suppresses macroscopic segregation and increases the solid solubility of alloying elements. Based on this, only a few cold rolling passes are required to stably produce 5-micrometer-scale ultrathin foils, significantly improving production efficiency and product yield (reaching over 85%). Attached Figure Description

[0024] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the overall structure of the constantan ultrathin foil preparation equipment in an embodiment of the present invention; Figure 2 for Figure 1 A partially enlarged cross-sectional view of the slit nozzle at the bottom of the intercooled crucible; Figure 3 Photograph of a 20-micron constantan strip obtained in Example 1 of this invention; Figure 4 Photograph of the 5.5-micron foil material made from constantan strip obtained in Example 1 of this invention after rolling; Figure 5 A schematic diagram showing the relationship between the thickness variation of the thin strip under different gas pressures; In the figure: 1-Suspension melting chamber; 2-Cold crucible; 3-Controllable inert gas pressurization system; 4-Thin strip collection device; 5-Thin strip guiding device and tension control device; 6-Rotating cooling roller; 7-Slit nozzle. Detailed Implementation

[0025] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0026] Adopting such Figure 1 The apparatus shown is used for the preparation of constantan ultrathin foil. The apparatus includes: A suspension melting chamber 1 with a cold crucible 2; the cold crucible 2 adopts a segmented copper alloy water-cooling structure, and realizes full suspension melting of alloy raw materials through a high-frequency induction coil. A slit nozzle 7 is disposed at the bottom of the cold crucible 2; the slit width of the slit nozzle 7 is adjustable to adapt to the production of thin strips with different thickness requirements.

[0027] A controllable inert gas pressurization system 3 is connected to the melting chamber 1. In this embodiment, the controllable inert gas pressurization system 3 generally includes an argon storage tank, a pressure reducing valve, a proportional regulating valve, and a pressure sensor, with a working pressure range of 10-200 kPa.

[0028] The rotating cooling roller 6 and the thin strip collecting device 4 are located below or to the side of the melting chamber. In this embodiment, the rotating cooling roller 6 can be a copper alloy cooling roller (diameter Φ100-600mm) with liquid nitrogen or the like circulating inside. The thin strip collecting device 4 generally includes a precision linear speed control system driven by a servo motor (speed range 4-60m / s), a dual-station automatic winding mechanism (maximum roll diameter Φ500mm), and an air-expansion shaft type core fixing device (compatible with 3 / 6 inch cores). The thin strip guide device and tension control device 5 located on one side of the cooling roller ensure smooth winding of the thin strip. In this embodiment, the thin strip guide device generally adopts a guide mechanism composed of three sets of ceramic guide rollers (with adjustable spacing), and the tension control device generally includes a pneumatic constant tension control system (control accuracy ±0.5N), an online laser thickness gauge (monitoring range 5-50μm), etc.

[0029] Example 1 (1) Raw material preparation: Select electrolytic Cu, electrolytic Ni and electrolytic Mn with a purity of 99.95% and prepare them precisely according to the mass percentage Cu-43Ni-1.5Mn, with a total weight of 5kg.

[0030] (2) Suspension melting: Load the raw materials into cold crucible 1, close the furnace chamber, and evacuate to 5×10 - The pressure is 3 Pa. The cold crucible adopts a segmented water-cooled copper crucible structure with 24 segments and a slit width of 0.3 mm between the segments to ensure effective penetration of magnetic field lines. High-purity argon gas is then introduced to 0.06 MPa. A high-frequency power supply is started at 250 kHz, and the power is gradually increased to 80 kW to completely melt the raw materials. The melting temperature is controlled at 1350 ± 20℃ and held at this temperature for 5 minutes to ensure homogenization of the alloy composition. Throughout the melting process, the melt can be observed to float in the center of the crucible under the influence of electromagnetic force, without contact with the crucible wall.

[0031] (3) Gas pressure extrusion: After the heat preservation is completed, the melting chamber is sealed, and high-purity argon gas is applied to the liquid surface through the pressurization system 2. The gas pressure is set to 120 kPa. Under pressure, the melt is uniformly extruded from the slit nozzle 3 located at the bottom of the crucible, with a slit width of 0.3 mm and a length of 100 mm, forming a stable sheet-like melt jet 4. The nozzle is made of boron nitride, which has good thermal shock resistance and anti-wetting properties.

[0032] (4) Rapid solidification: The cooling roller drive system is pre-activated to stabilize the linear velocity of the mirror roller 5 at 22 m / s, and 20°C circulating cooling water is supplied inside the roller. After the melt jet 4 is sprayed onto the surface of the roller 5, the contact length with the roller surface is 80 mm, and the solidification proceeds at approximately 10... 5Rapid cooling and solidification at a speed of K / s. The resulting continuous thin strip detaches from the roller under the action of inertial force and peeling airflow, and is wound up by the winding machine 7 via the guide device 6, with the winding tension controlled at 5-8N.

[0033] (5) Result Inspection: Measured by an online thickness gauge, the obtained constantan strip has a uniform thickness, with an average thickness of 19.5 micrometers, a thickness fluctuation of ≤±1.5 micrometers, and a width of 95 mm (e.g., ...). Figure 3 As shown in the figure, the composition is homogeneous and free of segregation. Resistivity was measured using the four-point probe method; the room temperature resistivity was 0.49 μΩ·m, and the temperature coefficient of resistance was ±20 × 10⁻⁶. -6 / ℃.

[0034] Example 2 This embodiment is basically the same as Embodiment 1, except that the process parameters are adjusted to examine the effect on the thickness of the thin strip.

[0035] Constantan ribbons were prepared by fixing the slit width at 0.3 mm and the roller speed at 20 m / s, and changing the gas pressure to 50 kPa, 100 kPa, 150 kPa, and 200 kPa. The results (e.g.) Figure 5 As shown in the figure, the thickness of the thin strip increases from 12 micrometers to 28 micrometers with increasing gas pressure, showing a good linear relationship, proving that the thickness of the thin strip can be precisely controlled by gas pressure.

[0036] Example 3 This embodiment is basically the same as Embodiment 1, except that the alloy composition is adjusted.

[0037] The alloy was prepared according to the Cu-40Ni-2Mn mass percentage, with the remaining steps the same as in Example 1. The resulting strip was 20.5 micrometers thick, with a resistivity of 0.48 μΩ·m and a temperature coefficient of resistance of ±18 × 10⁻⁶. -6 / ℃, meeting the requirements of precision resistance alloys.

[0038] Example 4 Subsequent rolling experiments: The 20-micron constantan strip obtained in Example 1 was ultrasonically cleaned with acetone and then cold-rolled on a precision four-high mill. The roll diameter was 80 mm, the rolling speed was 5 m / min, and mineral oil lubrication was used. Rolling was performed in three passes with reductions of 40%, 35%, and 30% respectively, resulting in a total processing yield of approximately 72%, ultimately obtaining constantan foil with a thickness of 5.5 microns (e.g., ...). Figure 4 (As shown). No cracks were generated in the strip during the rolling process, and the surface finish was good (Ra≤0.2μm). After testing, the tensile strength of the rolled foil was 520MPa, the elongation was 2.5%, and the resistivity was 0.50 μΩ·m.

[0039] Comparative Example 1 As a comparison, a conventional process was used to prepare constantan foil: a uniform alloy (Cu-43Ni-1.5Mn) was vacuum induction melted, cast into a 40mm thick ingot, hot-rolled to 3mm, and then subjected to 12 passes of cold rolling and 3 intermediate annealing processes to finally obtain a 5.5-micron foil. The results showed that the conventional process took 3.5 times longer than the present invention, had a yield of only 65%, and produced slight cracks and uneven grain size on the foil surface.

[0040] Comparative Example 2 A constantan strip was prepared using a tilting casting combined with strip casting process as a comparison: the same alloy composition was used, and the strip was tilted and cast onto rolls with the same linear speed after ordinary induction melting. The results showed that the strip thickness fluctuated greatly (15-40 micrometers), the width was uneven (the maximum width difference reached 15 mm), and there were porosity inclusions, which could not meet the requirements of subsequent precision rolling.

[0041] In summary, this invention achieves the following technical effects through the integrated innovation of cold crucible suspension melting, gas pressure extrusion, and rapid solidification: 1. Breakthrough in quality at the source; Suspension melting achieves zero melt contamination (comparative example 2 shows porosity and inclusions), and the uniformity of element distribution is improved by 300% (grain size 5-8μm VS 10-30μm in comparative example 1). 2. Process innovation Near-net-shape thin strips can be directly prepared, eliminating the ingot casting / hot rolling process and shortening the production cycle by 65% ​​(Example 1: 3.5 hours vs. Comparative Example 1: 12 hours). 3. Significant improvement in the precision of thin strips Pneumatic-roller speed coordinated control resulted in thickness fluctuation ≤ ±7.7% (±1.5μm in Example 1) and width consistency of 98% (width difference of 15mm in Comparative Example 2). 4. Excellent overall performance The final foil yield is ≥85% (compared to only 65% ​​in Comparative Example 1), and the temperature coefficient of resistance is stable at ±20×10⁻⁶. -6 / ℃ (meets IEC 60195 standard); 5. Energy consumption is significantly reduced. Energy consumption per unit product decreased by 42% (measured at 1.8 kWh / kg vs. 3.1 kWh / kg with traditional process).

[0042] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A short process for the production of high performance precision electrical resistance alloy foils, characterized in that, Includes the following steps: Step 1: Place the constantan alloy raw material in a cold crucible for suspension melting to obtain a pure and homogeneous alloy melt; Step 2: In a sealed environment, inert gas is introduced into the melting chamber, and the alloy melt is forced out through the extrusion channel at the bottom of the crucible using gas pressure to form a melt jet; Step 3: The melt jet is sprayed onto the surface of a high-speed rotating cooling roller, where it is cooled and solidified to form a crystalline ribbon.

2. A short flow process for the production of an extremely thin foil of a high performance precision resistance alloy as claimed in claim 1, characterized in that In step S1, the constantan alloy contains, by mass percentage, 39%-49% Ni, 1%-5% Mn, and the balance is Cu.

3. The short flow process for making an ultra-thin foil of high performance precision resistance alloy as claimed in claim 1, wherein the steps of the process are characterized by, The extrusion channel uses a slit nozzle with a slit width of 0.1-2.0 mm, and the pressure control range of the inert gas is 10-200 kPa.

4. The short flow process for making an ultra-thin foil of a high performance precision resistance alloy as claimed in claim 3, wherein the alloy is a high performance precision resistance alloy consisting of 80% of Ni, 10% of Cr, 5% of Fe, 3% of Si, 1% of Al and 1% of Ti. The length of the slit nozzle is 50-160 mm.

5. The short flow process for making an ultra-thin foil of a high performance precision resistance alloy as claimed in claim 1, wherein the alloy is a high performance precision resistance alloy consisting of 80% of Ni, 10% of Cr, 5% of Fe, 3% of Si, 1% of Al and 1% of Ti. The linear speed of the cooling roll in step 3 is 4-60 m / s, and the cooling speed is 10 2 -10 6 K / s, and the thickness of the crystalline thin ribbon is 10-60 microns.

6. The short-process preparation method of high-performance precision resistance alloy ultrathin foil as described in claim 1, characterized in that, It also includes step 4: precision cold rolling the crystalline strip obtained in step 3 to finally obtain constantan foil with a thickness of 3-10 micrometers.

7. An apparatus for preparing constantan ultrathin foil for implementing the method according to any one of claims 1-6, characterized in that, include: A suspended melting chamber with a cold crucible; A slit nozzle is provided at the bottom of the cold crucible; A controllable inert gas pressurization system connected to the melting chamber; And a rotating cooling roller and a thin strip collecting device located below or to the side of the melting chamber.

8. The constantan ultrathin foil preparation equipment as described in claim 7, characterized in that, The slit width of the slit nozzle is adjustable.

9. The constantan ultrathin foil preparation equipment as described in claim 7, characterized in that, The cooling roller is an automatically temperature-controlled roller with good wettability at the interface of the molten alloy, and it has a cooling medium flow channel inside.

10. The constantan ultrathin foil preparation equipment as described in claim 7, characterized in that, It also includes a thin strip guide device and a tension control device located on one side of the cooling roller.

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