Manufacturing method of metal composite seamless tube

Abstract

A manufacturing method of a metal composite seamless tube comprises the following steps that A, a strip-shaped boss is machined on the inner surface of an outer-layer tube blank, and a groove is machined in the outer surface of an inner-layer tube blank; b, the outer-layer pipe and the inner-layer pipe are assembled, the inner-layer pipe and the outer-layer pipe are in clearance fit, the joint lines at the two ends are sealed and welded, a small air outlet is reserved in each end, and the center lines of the inner-layer pipe and the outer-layer pipe coincide after welding; c, eliminating gaps among the racks through cold rolling or cold drawing, removing air among the racks, completing preliminary mechanical combination, and sealing and welding end combination lines again; d, medium-frequency induction heating is adopted for heat expansion, and metallurgical bonding and further mechanical bonding are achieved; and E, cold rolling or cold drawing to reach the required specification. The metal composite seamless pipe obtained through the technology has high mechanical bonding and metallurgical bonding and has good application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of seamless metal pipe production, in particular to a method for manufacturing a metal composite seamless pipe. Background Art

[0002] Metal seamless metal pipes are widely used. The requirements for metal seamless metal pipes required in many use environments are getting higher and higher, requiring expensive pipes made of stainless steel, nickel-based alloys, titanium and titanium alloys. In order to meet the use requirements and reduce production costs, composite metal pipes came into being. Bimetallic seamless metal pipes have the excellent properties of two metals and can obtain high strength, corrosion resistance and other properties. Therefore, they have broad application prospects in the petroleum, chemical, nuclear power and other industries.

[0003] At present, the commonly used production methods are mechanical compounding and metallurgical bonding (such as casting, cold rolling, cold drawing, extrusion and other process methods). However, the inner and outer layers of the composite pipe cannot be firmly bonded, and interlayer gaps are likely to appear during use, thereby greatly reducing the service life. In special occasions (such as high temperature, high pressure, etc.), the metal pipe is prone to instability or even bulging, rupture, etc., causing accidents.

[0004] For example: hot working method is a method of combining solid metals through thermoplastic deformation. The tube blank is composed of two metals of different materials, and then heated and perforated / extruded. Its main disadvantage is that the wall thickness deviation of the composite tube formed by severe hot working deformation (such as perforation and extrusion molding) is large, and the unevenness of the wall thickness is further increased in the subsequent machining process. In addition, due to the influence of tangential stress during the perforation process, the bimetal will produce gap oxidation during the deformation process, which has a great influence on the bonding strength.

[0005] Another example: the centrifugal casting method can ensure the bonding strength of each layer of metal, but its main disadvantage is that in many cases, the surface of the tube needs to be machined, which increases the uneven thickness of the two layers of metal, and also forms a transition layer due to the mutual erosion and mixing of liquid metal during casting. In addition, this method cannot produce composite metal tubes with light alloy outer layers. Summary of the invention

[0006] The purpose of the present invention is to provide a method for manufacturing a metal composite seamless pipe, which can effectively solve the problems in the background technology.

[0007] The technical solution to achieve the above purpose is: A method for manufacturing a metal composite seamless pipe, characterized by the following specific steps: S1. Assembly: Select multiple seamless metal tubes according to the finished product specifications, and sequentially insert and coaxially arrange the seamless metal tubes from the inside to the outside. A strip boss and a groove for matching insertion are arranged between two adjacent seamless metal tubes. A gap is arranged between the two adjacent seamless metal tubes and between the strip bosses and the corresponding grooves between the two adjacent seamless metal tubes. Clean the inner and outer walls of the seamless metal tubes before inserting. After the inserting is completed, seal and weld the ports at both ends of the two adjacent seamless metal tubes to obtain a composite tube body. Air outlet holes are left at the welding positions at both ends of the two adjacent seamless metal tubes. S2, mechanical compounding: one or more cold rolling or cold drawing processes with a mandrel are used to eliminate the gap between two adjacent seamless metal tubes in the primary composite tube body, and the matching strip bosses and grooves of the two adjacent seamless metal tubes are initially plastically deformed to produce mechanical compounding, and the ports of the two adjacent seamless metal tubes are sealed and welded again to obtain a secondary composite tube body; S3, Metallurgical Composite: Use medium frequency induction or heating furnace to heat the secondary composite pipe once or multiple times, and the expansion amount is not less than 10%; S4, post-process: cold rolling or cold drawing is carried out according to product specifications to achieve the required specifications.

[0008] Furthermore, in step S1, the gaps between two adjacent seamless metal tubes and between two adjacent seamless metal tubes and the corresponding grooves are both 2 to 15 mm.

[0009] Furthermore, two seamless metal pipes are provided.

[0010] Furthermore, the cold rolling or cold drawing process in step S2 causes the outer diameter of the primary composite tube body assembled in step S1 to be reduced by at least 1.1 times the total gap between the seamless metal tubes, thereby ensuring that the gaps between the seamless metal tubes are eliminated, eliminating the internal air, and causing the matching strip bosses and grooves of the two adjacent seamless metal tubes to undergo preliminary mechanical compounding.

[0011] Beneficial effects of the present invention: The present invention adopts a mechanical composite structure of protrusions and grooves, which is more firm and reliable, and has better effect than direct mechanical composite on the surface of the metal pipe.

[0012] In the assembly process of the present invention, the end faces of the seamless metal tubes are sealed and welded, and then cold rolled or cold drawn to eliminate the gap, so that the protrusions and grooves of the adjacent seamless metal tubes that match each other undergo initial plastic deformation, resulting in mechanical bonding, which effectively avoids the problem that the traditional composite tubes are cold rolled or cold drawn with gaps, and foreign matter (lubricating media such as cold drawn graphite, lubricating oil and other lubricating media in cold rolling, etc.) inevitably enter the joint surface to cause pollution, thereby affecting the composite quality of the metal tube interface.

[0013] The subsequent thermal expansion of the present invention effectively realizes further mechanical bonding and metallurgical bonding; end face sealing welding is adopted after cold rolling or cold drawing, and medium frequency induction / heating furnace is used for heating, which effectively eliminates the problem of long-term overall heating and heat preservation in traditional heating furnaces, resulting in end cracking and oxidation of the bonding surface during the subsequent thermal deformation processes such as perforation, rolling, and extrusion.

[0014] The present invention uses cold rolling or cold drawing to achieve preliminary mechanical compounding, and medium frequency induction / heating furnace heating and thermal expansion to achieve further mechanical compounding and metallurgical compounding, which effectively avoids the influence of foreign matter on the bonding interface, making the compounding effect better than single mechanical compounding or metallurgical compounding, and the product has high uniformity and small wall thickness deviation.

[0015] The present invention adopts a cold rolling or cold drawing forming process to achieve the required specifications, and the product appearance and dimensional accuracy are high. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of the inner tube and the outer tube in the nested state in Example 1; Figure 2 This is a schematic diagram of the first welding state of the inner layer tube and the outer layer tube in the assembly process in Example 1; Figure 3 This is a schematic diagram of the state where the mechanical compounding process of the inner layer tube and the outer layer tube in Example 1 is completed; Figure 4 This is a schematic diagram of the structure of the inner tube, middle tube and outer tube in the nested state in Example 2. DETAILED DESCRIPTION Example 1

[0017] The following is a further description of a method for manufacturing a metal composite seamless pipe of the present invention in conjunction with the accompanying drawings and embodiments.

[0018] This embodiment takes the production of a bimetallic composite seamless metal tube with a grade of 316L stainless steel outer tube 1 and a grade of 20 carbon steel inner tube 2 and a finished product specification of φ960*50mm as an example, and the specific steps are as follows: S1. Material preparation: The specification of 316L stainless steel outer tube 1 is φ813*20mm, and the specification of 20 carbon steel inner tube 2 is φ766*50mm. The inner wall of the outer tube 1 is processed with 6 strip bosses 3, which are isosceles trapezoids with small ends facing inwards, with a height of 8mm. The outer wall of the inner tube 2 is processed with 6 strip grooves 4 of corresponding shapes, with a depth of 8mm. The inner and outer walls of the outer tube 1 and the inner tube 2 are kept clean. Figure 1 As shown; S2, assembly: the outer tube 1 and the inner tube 2 are assembled together, the outer tube 1 and the inner tube 2 are coaxially arranged and gap-matched, the gap a between the outer tube 1 and the inner tube 2, and between the strip boss 3 and the corresponding strip groove 4 between the outer tube 1 and the inner tube 2 are both 3.5 mm, and the ports at both ends of the outer tube 1 and the inner tube 2 are sealed and welded to obtain a composite tube, and the welding positions at both ends of the outer tube 1 and the inner tube 2 are provided with air outlet holes 5 to prevent foreign matter from entering, as shown in detail. Figure 2 As shown; S3, Mechanical compound: Cold rolled to φ805*69.5mm, remove the internal air (such as Figure 3 As shown), before the next step of processing, the ports at both ends are sealed and welded again (the welding position is damaged in the cold rolling process) to obtain a secondary composite tube to prevent internal oxidation during heating; The cold rolling process reduces the outer diameter of the primary composite tube body assembled in step S2 by at least 1.1 times the gap between the outer tube 1 and the inner tube 2, thereby ensuring that the gap between the outer tube 1 and the inner tube 2 is eliminated and that a preliminary mechanical composite occurs between the strip boss 3 and the groove 4 between the outer tube 1 and the inner tube 2.

[0019] S4, Metallurgical Composite: Use medium frequency induction heating to heat expand the secondary composite pipe twice, the heating temperature is 1200℃, and the diameter is expanded to φ1130*55mm; S5, cold drawn to φ960*50mm. Example 2

[0020] like Figure 4 As shown, this embodiment takes the inner layer tube 6 of 5083 aluminum alloy, the outer layer tube 7 and the middle layer tube 8 of AZ31 magnesium alloy, and the finished product specification of φ255*20mm as an example of tube production, and the specific steps are as follows: S1. Material preparation: The specifications of the inner tube 6 and the outer tube 7 of 5083 aluminum alloy are: φ136*6mm, φ220*8mm, the specifications of the middle tube 8 of AZ31 magnesium alloy is φ200*30mm, the outer wall of the inner tube 6 and the inner wall of the outer tube 7 are respectively processed with two strip bosses 9, the strip bosses 9 are isosceles trapezoids with the small end facing inward, and the height is 2mm, the inner and outer walls of the middle tube 8 are respectively processed with two strip grooves 10 that match the strip bosses 9 on the inner tube 6 and the outer tube 7, the groove depth of the strip grooves 10 is 2mm, and the inner and outer walls of the inner tube 6, the outer tube 7, and the middle tube 8 are kept clean; S2, assembly: the middle tube 8 is sleeved on the inner tube 6, the outer tube 7 is sleeved on the middle tube 8, and the inner tube 6, the outer tube 7, and the middle tube 8 are coaxially arranged and respectively matched with clearances. The clearances between the middle tube 8 and the inner tube 6, between the outer tube 7 and the middle tube 6, and between the strip bosses 9 on the inner tube 6 and the outer tube 7 and the corresponding strip grooves 10 on the middle tube 8 are all 2 mm. The ports at both ends of the outer tube 7 and the middle tube 8, and the ports at both ends of the inner tube 6 and the middle tube 8 are sealed and welded to obtain a composite tube. The welding positions of the outer tube 7 and the middle tube 8, and the welding positions of the middle tube 8 and the inner tube 6 are all provided with air vents to prevent foreign matter from entering. S3, mechanical compounding: cold rolling to φ215*41mm, exhausting the internal air, before the next processing, the ports between the outer layer tube 1 and the middle layer tube 9, and the ports between the inner layer tube 6 and the middle layer tube 8 are sealed and welded again to obtain a secondary composite tube to prevent internal oxidation during heating; The cold rolling process reduces the outer diameter of the primary composite tube body assembled in step S2 by at least 1.1 times the total gap between the inner tube 6, the middle tube 8, and the outer tube 7, thereby ensuring that the gaps between the outer tube 7 and the middle tube 8, and between the middle tube 8 and the inner tube 6 are eliminated, and that the strip bosses 9 and the grooves 10 between the outer tube 7 and the middle tube 8, and between the middle tube 8 and the inner tube 6 are preliminarily mechanically composited.

[0021] S4, metallurgical composite: using electric furnace heating, the heating temperature is 380 ℃, the secondary composite pipe is thermally expanded twice, and the diameter is expanded to φ280*25mm; S5, cold rolled to φ255*20mm.

[0022] The manufacturing method of a metal composite seamless pipe of the present invention realizes the industrialized production of composite seamless metal pipes, reduces the production process cost and operation difficulty on the basis of ensuring a stable interface bonding strength, and meets the production requirements of high-end composite seamless metal pipes. It also has certain reference and application value for other similar metal composite seamless metal pipes.

Claims

1. A method for manufacturing a metal composite seamless pipe, characterized in that: Specific steps: S1. Assembly: Select multiple seamless metal tubes according to the finished product specifications, and sequentially insert and coaxially arrange the seamless metal tubes from the inside to the outside. A strip boss and a groove for matching insertion are arranged between two adjacent seamless metal tubes. A gap is arranged between the two adjacent seamless metal tubes and between the strip bosses and the corresponding grooves between the two adjacent seamless metal tubes. Clean the inner and outer walls of the seamless metal tubes before inserting. After the inserting is completed, seal and weld the ports at both ends of the two adjacent seamless metal tubes to obtain a composite tube body. Air outlet holes are left at the welding positions at both ends of the two adjacent seamless metal tubes. S2, mechanical compounding: one or more cold rolling or cold drawing processes with a mandrel are used to eliminate the gap between two adjacent seamless metal tubes in the primary composite tube body, and the matching strip bosses and grooves of the two adjacent seamless metal tubes are initially plastically deformed to produce mechanical compounding, and the ports of the two adjacent seamless metal tubes are sealed and welded again to obtain a secondary composite tube body; S3, Metallurgical Composite: Use medium frequency induction or heating furnace to heat the secondary composite pipe once or multiple times, and the expansion amount is not less than 10%; S4, post-process: cold rolling or cold drawing is carried out according to product specifications to achieve the required specifications.

2. The method for manufacturing a metal composite seamless pipe according to claim 1, characterized in that: In step S1, the gaps between two adjacent seamless metal tubes and between two adjacent seamless metal tubes and the corresponding grooves are both 2 to 15 mm.

3. The method for manufacturing a metal composite seamless pipe according to claim 1, characterized in that : Two seamless metal tubes are provided.

4. The method for manufacturing a metal composite seamless pipe according to claim 1, characterized in that: The cold rolling or cold drawing process in step S2 reduces the outer diameter of the primary composite pipe body assembled in step S1 by at least 1.1 times the total gap between the seamless metal pipes.

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