A method for producing a microchannel current collecting aluminum tube

Abstract

The present invention discloses a method for producing a microchannel current collecting aluminum tube. First, an aluminum ingot is extruded by a hot extruder to form a core tube and an outer composite tube; multiple core tubes are fed into a coating machine at a speed of 10 to 55 meters per minute, and a brazing strip is simultaneously fed in at the same time; an online continuous annealing process is used to heat the fed core tube and the brazing strip until the temperature of the core tube and the brazing strip is close to a molten state, the brazing strip is wrapped on the outer surface of the multiple core tubes under the action of the coating machine, and the butt joint of the brazing strip is welded under the protection of an inert gas to obtain a composite core tube; the oxide layer on the surface of the composite core tube is removed and polished; the composite core tube is continuously cold-drawn and heat-treated at least once; finally, the outer composite tube is nested in the outer wall of the composite core tube, and the size of the composite tube reaches a target value after at least one cold-drawing and heat-treatment. The present invention has stronger corrosion resistance and lower processing cost relative to the multi-layer sleeve cold-drawing method.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum pipe production, and in particular relates to a production and processing method for a small-diameter header. Background Art

[0002] Microchannel headers are widely used in air conditioning heat exchangers. They have excellent heat transfer characteristics and have improved traditional industrial refrigeration, automotive air conditioning, computer room air conditioning and household air conditioning, effectively improving energy utilization and reducing emissions. At present, most traditional microchannel headers use aluminum composite strips, which are formed by brazing the core material and micro-tubes through multiple cold drawing and hot rolling technologies. The butt welding joints formed during the cold rolling process are prone to welding defects, which lead to a decrease in the mechanical properties and corrosion resistance of the header. Summary of the invention

[0003] Purpose of the invention: In view of the above existing problems and shortcomings, the purpose of the present invention is to provide a method for producing a microchannel collector aluminum tube, which can improve the corrosion resistance and mechanical strength of the collector tube.

[0004] Technical solution: To achieve the above invention purpose, the present invention adopts the following technical solution: A method for producing a microchannel current collecting aluminum tube, comprising the following steps:

[0005] S1: First, an aluminum ingot is extruded into a core tube and an outer composite tube by a hot extruder;

[0006] S2: feeding a plurality of core tubes into a cladding machine at a speed of 10-55 m / min, and simultaneously feeding a brazing strip; heating the fed core tubes and the brazing strip by an online continuous annealing process until the temperature of the core tubes and the brazing strip is close to a molten state, wrapping the brazing strip on the outer surface of the plurality of core tubes under the action of the cladding machine, and welding the butt joints of the brazing strips under the protection of an inert gas to obtain a composite core tube;

[0007] S3: removing the oxide layer on the surface of the composite core tube and performing polishing;

[0008] S4: Continue to cold draw and heat treat the composite core tube at least once;

[0009] S5: Finally, the outer composite tube is nested in the outer wall of the composite core tube, and subjected to at least one cold drawing and heat treatment, so that the size of the composite tube reaches the target value.

[0010] Preferably, the specific process of cold drawing and heat treatment in step S4 is as follows: after the composite core tube is cold drawn for the first time, it is heated to a state close to being molten, and the above cold drawing and heat treatment process is repeated 1-5 times.

[0011] Preferably, in step S4, the composite core tube is subjected to twisting cold drawing during the last cold drawing and heat treatment so that the multiple core tubes are formed into a twisted core tube bundle.

[0012] Preferably, the core tube in step S1 is made of 1, 3 or 5 series aluminum alloy, and the outer composite tube is made of 2 or 7 series aluminum alloy.

[0013] Preferably, in step S1, the core tube has a diameter of 10-80 mm and a wall thickness of 12-55 mm; the outer composite tube has a diameter of 20-200 mm and a wall thickness of 12-100 mm.

[0014] Preferably, in step S2, the heating temperature of the core tube and the brazing strip is 15-50° C. lower than their melting points.

[0015] Preferably, in step S3, after removing the surface oxide layer of the composite core tube, a polishing process is performed to make the outer surface roughness of the composite core tube less than 0.025 μm and the surface finish less than 0.02 μm.

[0016] Preferably, in step S4, cold drawing is performed by coil drawing or straight drawing, and the cross-section processing rate of each cold drawing pass is 5-60%; and the heat treatment temperature is 300-420°C.

[0017] Preferably, the outer composite pipe is a spiral internal threaded pipe or a straight tooth internal threaded pipe.

[0018] Beneficial effects: Compared with the prior art, the present invention uses a flexible grade aluminum alloy brazing strip to melt and combine multiple core tubes to form an inner core tube bundle of a microchannel, which improves the processing and stamping resistance of the composite aluminum tube and has stronger corrosion resistance; and the processing cost is lower than that of the multi-layer sleeve cold drawing method. DETAILED DESCRIPTION

[0019] The present invention is further illustrated below with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, modifications of various equivalent forms of the present invention by those skilled in the art all fall within the scope defined by the appended claims of the present application.

[0020] The microchannel current collecting aluminum tube of the present invention is formed by combining multiple core tubes, brazing sleeves and outer composite tubes, and then undergoing multiple cold drawing and heat treatment. The core tube is preferably made of 1060 or 3003 grade aluminum ingots; the outer composite tube is preferably made of 2014 or 7005 / 7075 grade aluminum ingots. The production method is specifically introduced by taking a 65mm outer envelope diameter current collecting tube as an example:

[0021] In the first step, first, the core tube and the outer composite tube are extruded separately by a horizontal hot extruder;

[0022] In the second step, multiple core tubes are fed into a coating machine at a speed of 30-40 m / min, and brazing strips are fed into the coating machine at the same time at a synchronous speed, and the outer surface is polished with a metal brush during feeding; at the same time, the fed core tubes and brazing strips are heated by an online continuous annealing process until the temperature of the core tubes and the brazing strips reaches 350-400°C, which is close to a molten state, and the brazing strips are wrapped around the outer surfaces of the multiple core tubes under the action of the coating machine, and the butt joints of the brazing strips are welded under the protection of an inert gas to obtain a composite core tube blank, which is then extruded and tightly combined under die extrusion at a temperature of about 400°C;

[0023] The third step is to remove the oxide layer on the surface of the composite core tube if necessary, and perform online polishing to make the outer surface roughness of the composite core tube less than 0.025 μm and the surface finish less than 0.02 μm through the polishing process. ;

[0024] The fourth step is to repeat the cold drawing and heat treatment of the composite core tube for 1-5 times; in this process, preferably, coil drawing or straight drawing is used for cold drawing, and the cross-section processing rate of each cold drawing is 5-60%; preferably, when the cold drawing machine is rotated during the last cold drawing, the composite core tube is twisted, and the increase in contact area can effectively improve the heat dissipation efficiency of the collector;

[0025] In the fifth step, the outer composite tube is finally nested in the outer wall of the composite core tube, and after at least one cold drawing and heat treatment, the size of the composite tube reaches the target value. Compared with the high cost of the traditional commercially available aluminum composite aluminum strip or aluminum tube, the present invention directly uses aluminum ingots and aluminum strips for cladding welding and then extrusion molding, which greatly reduces the cost while improving the heat dissipation efficiency, mechanical strength and corrosion resistance of the collector.

Claims

1. A method for producing a microchannel current collecting aluminum tube, characterized in that The following steps are involved: S1: First, an aluminum ingot is extruded into a core tube and an outer composite tube by a hot extruder; S2: feeding a plurality of core tubes into a cladding machine at a speed of 10-55 m / min, and simultaneously feeding a brazing strip; heating the fed core tubes and the brazing strip by an online continuous annealing process until the temperature of the core tubes and the brazing strip is close to a molten state, wrapping the brazing strip on the outer surface of the plurality of core tubes under the action of the cladding machine, and welding the butt joints of the brazing strips under the protection of an inert gas to obtain a composite core tube; S3: removing the oxide layer on the surface of the composite core tube and performing polishing; S4: Continue to cold draw and heat treat the composite core tube at least once; S5: Finally, the outer composite tube is nested in the outer wall of the composite core tube, and subjected to at least one cold drawing and heat treatment, so that the size of the composite tube reaches the target value; In step S4, the composite core tube is subjected to twisting cold drawing during the last cold drawing and heat treatment so that the multiple core tubes form a twisted core tube bundle; The outer composite pipe is a spiral internal thread pipe or a straight tooth internal thread pipe.

2. The method for producing a microchannel current collecting aluminum tube according to claim 1, characterized in that: The specific process of cold drawing and heat treatment in step S4 is as follows: after the composite core tube is cold drawn for the first time, it is heated to a state close to melting, and the above cold drawing and heat treatment process is repeated 1-5 times.

3. The method for producing a microchannel current collecting aluminum tube according to claim 2, characterized in that: In step S1, the core tube is made of 1, 3 or 5 series aluminum alloy, and the outer composite tube is made of 2 or 7 series aluminum alloy.

4. The method for producing a microchannel current collecting aluminum tube according to claim 3, characterized in that: In step S1, the core tube has a diameter of 10-80 mm and a wall thickness of 12-55 mm; the outer composite tube has a diameter of 20-200 mm and a wall thickness of 12-100 mm.

5. The method for producing a microchannel current collecting aluminum tube according to claim 3, characterized in that: In step S2, the heating temperature of the core tube and the brazing strip is 15-50° C. lower than their melting points.

6. The method for producing a microchannel current collecting aluminum tube according to claim 3, characterized in that: In step S3, after removing the surface oxide layer of the composite core tube, a polishing process is performed to make the outer surface roughness of the composite core tube less than 0.025 μm and the surface finish less than 0.02 μm.

7. The method for producing a microchannel current collecting aluminum tube according to claim 3, characterized in that: In step S4, cold drawing is performed by coil drawing or straight drawing, and the cross-section processing rate of each cold drawing pass is 5-60%; the heat treatment temperature is 300-420°C.