JP2024086565A - Composite device for gradually skew-rolling composite thin wall pipe composed of heterogeneous metal having large length diameter ratio, and method of the same - Google Patents

Abstract

To provide a composite device for suppressing imbalance, dust and cracks when a composite thin wall pipe composed of heterogeneous metal is molded, and a method of the same.SOLUTION: There are provided a composite device for gradually skew-rolling a composite thin wall pipe composed of heterogeneous metal having a large length diameter ratio and a method of the same, wherein the device includes a core bar carrying vehicle 1, a core bar 2, a previously coated work in process 3, an electromagnetic induction heating device 4, a gradual skew-rolling device 5 and a feed rail 6 installed in this order along a rolling axis, the gradual skew-rolling device includes a rolling roll and a clearance plate, the rolling roll is a cone-shaped rolling roll, the rolling roll is composed of an inlet cylindrical region, an inlet cone region, a gradual reduced region, a finish region, an outlet cone region and an outlet cylindrical region installed in this order in a rolling axis direction, the gradual reduced region is composed of only N pieces of strong reduced parts and weak reduced parts installed by replacement, and large deformation is accumulated and achieved through continuous small rolling in plural stages.SELECTED DRAWING: Figure 1

Description

The present invention relates to the technical field of forming composite metal tubes, and in particular to a composite device and method for progressively tilt rolling composite thin-walled tubes made of dissimilar metals with a large length-to-diameter ratio.

Composite pipes made of dissimilar metals are structural and functional materials that simultaneously possess comprehensive properties such as rigidity, strength, corrosion resistance and abrasion resistance. Special deformation and connection techniques are used to form a tight bond between the substrate and coating layer, maximizing the advantages of the metallic elements of each component while overcoming the deficiencies of single metallic performance, significantly reducing application costs and providing excellent comprehensive performance and economic benefits. They have a wide range of prospects for application in fields such as nuclear power generation, petrochemical industry, marine industry, power electronics, machinery manufacturing and architectural decoration.

In recent years, researchers at home and abroad have been conducting a great deal of research into the process of producing composite pipes made of dissimilar metals, and have provided typical production technologies such as explosive composite method, drawing composite method, and continuous rolling composite method, which have accelerated the development of the industry. The explosive composite method can bond metallurgy at the composite interface between multiple component metals by using the shock wave and high temperature and high energy generated at the moment of explosion of the explosive, but it cannot realize continuous forming, and there is chemical and noise pollution. The drawing composite method is to coat the heterogeneous metal pipe material, and then draw the outer and inner pipes by a cone mold to reduce/expand the diameter in the axial direction, and through plastic deformation and elastic recovery, a tight mechanical bond can be formed between the inner and outer pipes. Its characteristics are that the process is simple and the forming efficiency is high, but the contact area between the cone mold and the pipe material is relatively large, so the forming force required is relatively large and the energy consumption is relatively high. The continuous rolling composite method uses multiple groups of Y-type rolling mills to continuously perform small deformations through multiple steps at high temperatures to achieve metallurgical bonding at the interface. Its features include high production efficiency and high yield, but the cost of the required equipment is relatively high, the production line is several hundred meters long, the control of the continuous hot rolling process is extremely complicated, and it is difficult to adjust the product specifications.

The process of forming composite pipes made of dissimilar metals requires coating and combining the in-process outer and inner pipe materials. There are relatively high requirements for assembly precision, concentricity, surface quality, etc. For products with a large length-to-diameter ratio, coating is difficult and the forming efficiency is relatively low, which has significantly limited the application and popularization of composite pipes made of dissimilar metals. In addition, for composite thin-walled pipes made of dissimilar metals, both the outer and inner pipe materials are relatively thin, so that typical defects such as imbalance, dust, and cracks are very likely to appear during forming, and there is a big challenge in performing continuous and stable forming.

In response to the above problems, the present invention provides a composite apparatus and method for progressively tilt rolling composite thin-walled tubes made of dissimilar metals with a large length-to-diameter ratio.

To achieve the above objective, the present invention employs the following technical means:

A composite device for gradually tilt rolling a composite thin-walled tube made of dissimilar metals with a large length-to-diameter ratio includes a core rod transport car, a core rod, a pre-coated workpiece, an electromagnetic induction heating device, a progressive tilt rolling machine, and a feed track, which are sequentially installed along a rolling axis. The core rod transport car is for linking the core rod so that it moves back and forth along the rolling axis. The pre-coated workpiece covers the core rod. The electromagnetic induction heating device is installed on the entrance side of the progressive tilt rolling machine and for heating the pre-coated workpiece immediately before it enters the progressive tilt rolling machine. The progressive tilt rolling machine is for rolling the pre-coated workpiece, and the feed track is installed at the exit of the progressive tilt rolling machine and for feeding the pre-coated workpiece that has been rolled and combined. The progressively inclined rolling equipment includes a rolling roll and a spacing plate, the rolling roll being a conical rolling roll, the rolling roll being composed of an entrance circular corner region, an entrance cone region, a gradual wall thickness reduction region, a finishing region, an exit cone region, and an exit circular corner region, which are arranged in sequence along the rolling axis direction, and the gradual wall thickness reduction region is composed of only N strong wall thickness reduction sections and weak wall thickness reduction sections arranged alternately.

Furthermore, the entrance circular angular region is an arc with a radius of r, both ends of which are in contact with the entrance end face of the rolling roll and the conical surface of the entrance cone region, respectively, and its length L1 is equal to r, where r is 1% to 4% of the outer diameter of the finishing region.

Furthermore, the entrance cone region has a length L2 of 20% to 40% of the rolling roll length, and a cone angle α2 of 2° to 6°. The finishing region has a length L4 of 20% to 40% of the rolling roll length, and a cone angle α4 of 0° to 1°. The exit cone region has a length L5 of 5% to 15% of the rolling roll length, and a cone angle α5 of 0° to 2°.

Furthermore, the gradual thickness reduction region has a length L3 of 30% to 50% of the rolling roll length, a cone angle α31 of the strong thickness reduction region is 10° to 20°, and a cone angle α32 of the weak thickness reduction region is 1° to 10°. The length L32 of the weak thickness reduction region is 2 to 10 times the length L31 of the strong thickness reduction region.

Furthermore, the exit circular angular region is an arc with a radius of r, both ends of which are in contact with the exit end face of the rolling roll and the conical surface of the exit conical region, respectively, and its length L6 is equal to r, which is equal to 1% to 4% of the outer diameter of the finishing region.

Furthermore, the pre-coated work-in-progress includes an outer layer pipe material, an inner layer pipe material, and a positioning ring, the inner diameter of the outer layer pipe material is larger than the outer diameter of the inner layer pipe material, the inner layer pipe material is covered inside the outer layer pipe material, there are two positioning rings, both ends of the outer layer pipe material and the inner layer pipe material are connected to the two positioning rings, the outer layer pipe material, the inner layer pipe material, and the positioning rings are installed coaxially, and a coating gap is provided between the outer layer pipe material and the inner layer pipe material.

A composite method for progressively tilt-rolling composite thin-walled tubes of dissimilar metals with large length-to-diameter ratios includes the following steps.
Step S1 is to cover the work-in-progress with a flexible material and assemble it. The surfaces of the outer and inner pipes are cleaned, and the work-in-progress is covered with a flexible material and assembled in the order of placing the outer pipe on the outside and the inner pipe on the inside, leaving a gap between the outer and inner pipes, and sealing and welding are performed using two positioning rings, followed by vacuuming, to complete the production of the covered work-in-progress.
Step S2 is heating by electromagnetic induction. The core rod transport car and the core rod are connected, the core rod passes through the pre-coated workpiece, and is sent to the electromagnetic induction heating device together with the core rod transport car at a speed v for heating, and the heating power and frequency are adjusted, so that when the pre-coated workpiece leaves the electromagnetic induction heating device, the surface to be combined in the outer layer pipe material and/or the inner layer pipe material is heated to a target temperature T, and when the target temperature T is reached, the pre-coated workpiece is sent to the gradual tilt rolling device via the core rod for rolling and combining.
Step S3 is to gradually perform tilt rolling and compounding. Adjust the roll and spacing plate of the gradually tilt rolling machine, set the target hole shape and shape D, start the gradually tilt rolling machine, send the mandrel and the pre-coated workpiece together to the gradually tilt rolling machine by the mandrel transport car, send the pre-coated workpiece into the roller gap surrounded by the mandrel, roll and spacing plate, and gradually perform tilt rolling and compounding, sequentially passing through the entrance circular corner area, the entrance cone area, the gradual wall reduction area, the finishing area, the exit circular corner area, the exit circular corner area, the diameter gradually decreases, the wall gradually becomes thinner, and the composite interface is metallurgically bonded, and finally obtain the composite thin-walled tube by rolling, and send it through the feed track.
Step S4 controls the heat treatment. The leading and trailing ends of the final rolled composite thin-walled tube are removed, and the tube is cut according to a predetermined size, and the tube is subjected to heat treatment to obtain a target structure performance, thereby obtaining a finished composite thin-walled tube.

Furthermore, the size of the coating gap is 0.2% to 5% of the outer diameter of the coated workpiece. This allows the workpiece to be flexibly coated and assembled between the outer layer pipe material and the inner layer pipe material with a large length-to-diameter ratio.

Furthermore, in step S3, the amount of diameter reduction during the process of gradually rolling inclined to form a composite is greater than 20% of the outer diameter of the coated workpiece, the amount of material reduction is greater than 40% of the total material of the coated workpiece, and the material non-uniformity is ≦5%.

Compared to conventional technology, the present invention has the following advantages:

The present invention uses the principle of electromagnetic induction heating to perform induction and heating on the outer layer pipe material or the inner layer pipe material in the coated work-in-progress in advance, thereby accurately controlling the temperature of the interface to be combined. This avoids problems such as longer overall heating time, higher energy consumption, more complex equipment, and larger land area taken up due to the inconsistent performance of the component metal materials, and significantly reduces energy consumption and shortens the processing flow.

The present invention addresses the problem of relatively high demands on assembly precision, concentricity, surface quality, etc., when coating the outer and inner layer pipe materials in composite pipes made of dissimilar metals with a large length-to-diameter ratio. It adopts a form in which the outer and inner layer pipe materials are flexibly coated with a gap in advance, and the gap that is pre-set is accurately controlled by positioning rings at both ends, making it possible to effectively coat pipe materials with a large length-to-diameter ratio and assemble the work-in-progress.

The rolling roll according to the present invention has a conical surface which is sequentially provided with an entrance corner region, an entrance cone region, a gradual wall thickness reduction region, a finishing region, an exit cone region and an exit corner region, among which the gradual wall thickness reduction region is made up of only N strong wall thickness reduction sections and weak wall thickness reduction sections which are arranged in an alternating manner, and by continuously accumulating small deformations through multiple steps, it is possible to solve typical defects such as imbalance, dust and cracks which often appear when forming composite thin-walled tubes made of different metals, and since the continuous small rolling through multiple steps is centrally installed in the same locking die, it is possible to realize continuous and stable forming, and has significant advantages such as high efficiency and short flow.

The device according to the present invention has a compact configuration, requires little investment in equipment and space, and can continuously form composite thin-walled tubes made of dissimilar metals using a progressive tilt rolling machine. The pre-coated workpiece is gradually tilt rolled and combined in a roller gap surrounded by a core rod, rolling rolls, and spacing plates. By adjusting the size of the core rod, the rolling roll type, and the position of the spacing plates, products of different specifications can be produced, and the device can be used to process metals that are easy to deform, such as copper and aluminum, steel and aluminum, at room temperature, or to process metals that are difficult to deform, such as stainless steel/carbon steel, titanium/stainless steel, and titanium/copper, by heating. This device has the advantages of a wide variety of products, a wide range of sizes and specifications, high production efficiency, high forming accuracy, and good surface quality.

FIG. 1 is a schematic diagram showing a configuration according to the present invention. FIG. 2 is a schematic diagram showing the configuration of a pre-coated workpiece according to the present invention. FIG. 1 is a front view of a progressive tilt rolling machine according to the present invention; FIG. 2 is a schematic diagram showing a configuration of a reduction roll according to the present invention.

In order to explain the technical means of the present invention in detail, the present invention will be described in detail below based on examples.

As shown in Figures 1 to 4, the composite device for gradually tilt-rolling a composite thin-walled tube made of dissimilar metals with a large length-to-diameter ratio includes a core rod transport car 1, a core rod 2, a pre-coated workpiece 3, an electromagnetic induction heating device 4, a progressive tilt rolling machine 5, and a feed track 6, which are sequentially installed along the rolling axis. The core rod transport car 1 is for linking the core rod 2 so that it moves back and forth along the rolling axis. The pre-coated workpiece 3 covers the core rod 2. The electromagnetic induction heating device 4 is installed on the entrance side of the progressive tilt rolling machine 5 and is for heating the pre-coated workpiece 3 just before it enters the progressive tilt rolling machine 5. The progressive tilt rolling machine 5 is for rolling the pre-coated workpiece 3, and the feed track is installed at the exit of the progressive tilt rolling machine 5 and is for feeding the pre-coated workpiece 3 that has been rolled and combined.

The progressively inclined rolling equipment 5 includes a rolling roll 501 and a spacing plate 502, and the rolling roll 501 is a conical rolling roll. The rolling roll 501 is composed of an entrance circular corner region 5011, an entrance cone region 5012, a gradual wall reduction region 5013, a finishing region 5014, an exit cone region 5015, and an exit circular corner region 5016, which are arranged in sequence along the rolling axis direction. The entrance circular corner region 5011 is an arc with a radius of r, and both ends of the arc are in contact with the entrance end face of the rolling roll 501 and the cone surface of the entrance cone region 5012, respectively, and its length L1 is equal to r, and r is equal to 1% to 4% of the outer diameter of the finishing region 5014. The entrance cone region 5012 has a length L2 of 20% to 40% of the length of the rolling roll 501, and a cone angle α2 of 2° to 6°. The finishing region 5014 has a length L4 of 20% to 40% of the length of the rolling roll 501, and a cone angle α4 of 0° to 1°. The exit cone region 5015 has a length L5 of 5% to 15% of the length of the rolling roll 501, and a cone angle α5 of 0° to 2°. The exit angular region 5016 is an arc with a radius of r, and both ends of the arc are in contact with the exit end face of the rolling roll 501 and the cone surface of the exit cone region 5015, respectively, and the length L6 is equal to r, and r is equal to 1% to 4% of the outer diameter of the finishing region 5014. The gradual thickness reduction region 5013 is composed of only N strong thickness reduction portions 50131 and weak thickness reduction portions 50132 that are arranged in an interchangeable manner. The gradual thickness reduction region 5013 has a length L3 of 30% to 50% of the length of the rolling roll 501, in which the cone angle α31 of the strong thickness reduction portion 50131 is 10° to 20°, and the cone angle α32 of the weak thickness reduction portion 50132 is 1° to 10°. The length L32 of the weak thickness reduction portion 50132 is 2 to 10 times the length L31 of the strong thickness reduction portion 50131.

The pre-coated work-in-progress 3 includes an outer layer pipe material 301, an inner layer pipe material 302, and a positioning ring 303. The inner diameter of the outer layer pipe material 301 is larger than the outer diameter of the inner layer pipe material 302. The inner layer pipe material 302 is covered inside the outer layer pipe material 301. There are two positioning rings 303. Both ends of the outer layer pipe material 301 and the inner layer pipe material 302 are connected to the two positioning rings 303. The outer layer pipe material 301, the inner layer pipe material 302, and the positioning ring 303 are installed coaxially, and a coating gap 304 is placed between the outer layer pipe material 301 and the inner layer pipe material 302.

A method for progressively tilt rolling and combining a composite thin-walled tube of dissimilar metals with a large length-to-diameter ratio includes the following steps.
In step S1, the work-in-progress is covered with a soft material and assembled. The surfaces of the outer layer pipe material 301 and the inner layer pipe material 302 are cleaned. The work-in-progress is covered with a soft material and assembled in the order of placing the outer layer pipe material 301 on the outside and the inner layer pipe material 302 on the inside. A coating gap 304 is placed between the outer layer pipe material 301 and the inner layer pipe material 302. The size of the coating gap 304 is 0.2% to 5% of the outer diameter of the pre-coated work-in-progress 3. Furthermore, two positioning rings 303 are used to perform sealing and welding, and then a vacuum is drawn. Then, the production of the pre-coated work-in-progress 3 is completed.
Step S2 is heating by electromagnetic induction. The core rod transport car 1 and the core rod 2 are connected so that the core rod 2 passes through the pre-coated workpiece 3. The core rod transport car 1 is used to transport the core rod 2 to the electromagnetic induction heating device 4 at a speed v for heating. The heating power and frequency are adjusted so that when the pre-coated workpiece 3 leaves the electromagnetic induction heating device 4, the surface to be combined in the outer layer pipe material 301 and/or the inner layer pipe material 302 is heated to the target temperature T, and when the target temperature T is reached, the pre-coated workpiece 3 is transported to the progressive tilt rolling device 5 via the core rod 2 for rolling and combining.
Step S3 is to gradually incline and roll the composite. The roll 501 and the spacing plate 502 of the gradually incline rolling machine 5 are adjusted. The shape of the target hole is set to be the shape D. The gradually incline rolling machine 5 is started, and the core rod 2 and the pre-coated workpiece 3 are sent to the gradually incline rolling machine 5 by the core rod transport car 1, and the pre-coated workpiece 3 is sent to the roller gap surrounded by the core rod 2, the roll 501 and the spacing plate 502 to gradually perform incline rolling and compounding. The diameter gradually decreases and the wall gradually becomes thinner through the entrance circular corner region 5011, the entrance cone region 5012, the gradual wall reduction region 5013, the finishing region 5014, the exit circular corner region 5015 and the exit circular corner region 5016, and the composite interface is metallurgically bonded. The finally rolled composite thin-walled tube is obtained and sent through the feed track 6. When gradually rolling inclined to combine, the amount of diameter reduction is greater than 20% of the outer diameter of the coated workpiece 3, the amount of wall reduction is greater than 40% of the entire wall of the coated workpiece 3, and the degree of wall non-uniformity is ≦5%.
Step S4 controls the heat treatment. The leading and trailing ends of the final rolled composite thin-walled tube are removed, and the tube is cut according to a predetermined size, and the tube is subjected to heat treatment to obtain a target structure performance, thereby obtaining a finished composite thin-walled tube.

By bringing the composite interface to the same temperature, a composite thin-walled tube made of 45 steel and 316L stainless steel is produced with a large length-to-diameter ratio.

The outer layer pipe material 301 is a 45 steel thin-walled pipe material with an outer diameter of 63 mm, a wall thickness of 2.4 mm, and a length of 8000 mm. The inner layer pipe material 302 is a 316L stainless steel thin-walled pipe material with an outer diameter of 57 mm, a wall thickness of 3 mm, and a length of 8000 mm. Between the outer layer pipe material 301 and the inner layer pipe material 302, the coating gap 304 is 0.4 mm, and the core rod 2 is 10000 mm long and 45 mm in diameter. The electromagnetic induction heating device 4 is a digital electromagnetic heater that is only applicable to steel, has a self-protection function, and has a maximum heating temperature of 1600°C.

The progressively inclined rolling device 5 has the following dimensions: the entrance circular arc region 5011 is an arc of radius r = 5 mm, its length L1 is equal to r, the entrance cone region 5012 has a length L2 = 60 mm, its cone angle α2 = 2°, the progressively thinning region 5013 has a length L3 = 120 mm, and includes only eight identical strong thinning regions 50131 and eight identical weak thinning regions 50132, the strong thinning regions 50131 having a cone angle α31 = 12°, length L31 = 5 mm, the weak wall reduction portion 50132 has a cone angle α32 = 2° and a length L32 = 10 mm, the finishing region 5014 has a length L4 = 70 mm and a cone angle α4 = 0°, the exit cone region 5015 has a length L5 = 25 mm and a cone angle α5 = 1°, the exit circular arc region 5016 is an arc with a radius r = 5 mm and a length L6 equal to r.

The production steps are as follows:

In step S1, the work-in-progress is covered with a soft material and assembled. The surfaces of the outer layer pipe material 301 and the inner layer pipe material 302 are cleaned. The work-in-progress is covered with a soft material and assembled in the order of the outer layer pipe material 301 on the outside and the inner layer pipe material 302 on the inside. A coating gap 304 is placed between the outer layer pipe material 301 and the inner layer pipe material 302. Sealing and welding are performed using two positioning rings 303, and then a vacuum is drawn. Then, the production of the coated work-in-progress 3 is completed in advance.

Step S2 is heating by electromagnetic induction. The core rod transport car 1 and the core rod 2 are connected, and the core rod 2 passes through the pre-coated workpiece 3. To heat it, both are sent to the electromagnetic induction heating device 4 at a speed v = 500 mm/s using the core rod transport car 1, and the heating power and frequency are adjusted. When the pre-coated workpiece 3 leaves the electromagnetic induction heating device 4, the surfaces to be combined in the outer layer pipe material 301 and the inner layer pipe material 302 are heated to the target temperature T = 1150 ° C., and when the target temperature T is reached, the pre-coated workpiece 3 is sent to the gradual tilt rolling device 5 via the core rod 2 for rolling.

Step S3 is to gradually incline and roll the composite. The roll 501 and the spacing plate 502 of the gradually incline rolling machine 5 are adjusted, the shape of the target hole is set to be D = 50 mm, the gradually incline rolling machine 5 is started, and the core rod 2 and the pre-coated workpiece 3 are sent to the gradually incline rolling machine 5 using the core rod transport car 1, and the pre-coated workpiece 3 is sent to the roller gap surrounded by the core rod 2, the roll 501 and the spacing plate 502 to gradually perform incline rolling and compounding, and the diameter gradually decreases and the wall gradually becomes thinner through the entrance circular corner region 5011, the entrance cone region 5012, the gradual wall reduction region 5013, the finishing region 5014, the exit circular cone region 5015 and the exit circular corner region 5016, and the composite interface is metallurgically bonded. When the finally rolled composite thin-walled tube is obtained, it is sent through the feed track 6.

Step S4 controls the heat treatment. The leading and trailing ends of the final rolled composite thin-walled tube are removed, the tube is cut to a specified size, and the tube undergoes heat treatment to obtain the target structural properties, resulting in a finished composite thin-walled tube.

By subjecting the composite interface to different temperatures, a composite thin-walled tube made of TC4 titanium alloy and 316L stainless steel with a large length-to-diameter ratio is produced.

The outer layer pipe material 301 is a thin-walled pipe material made of TC4 titanium alloy, with an outer diameter of 80 mm, a wall thickness of 3.5 mm, and a length of 8000 mm. The inner layer pipe material 302 is a thin-walled pipe material made of 316L stainless steel, with an outer diameter of 72 mm, a wall thickness of 4 mm, and a length of 8000 mm. The coating gap 304 between the outer layer pipe material 301 and the inner layer pipe material 302 is 0.5 mm. The core rod 2 is 10000 mm long and 58 mm in diameter. The electromagnetic induction heating device 4 is a digital electromagnetic heater that is only applicable to titanium alloys, has a self-protection function, and has a maximum heating temperature of 1200°C.

The dimensions of the progressively inclined rolling device 5 are as follows: the entrance circular arc region 5011 is an arc with a radius r = 5 mm and a length L1 equal to r, the entrance cone region 5012 has a length L2 = 60 mm and a cone angle α2 = 2°, the progressively reduced thickness region 5013 has a length L3 = 120 mm and includes eight identical strong reduced thickness regions 50131 and eight identical weak reduced thickness regions 50132, the strong reduced thickness regions 50131 having a cone angle α3 1 = 12°, length L31 = 5 mm, the weak reduced thickness portion 50132 has a cone angle α32 = 2° and a length L32 = 10 mm, the finishing region 5014 has a length L4 = 70 mm and a cone angle α4 = 0°, the exit cone region 5015 has a length L5 = 25 mm and a cone angle α5 = 1°, and the exit circular angle region 5016 is an arc with a radius r = 5 mm and a length L6 equal to r.

The production steps are as follows:

In step S1, the work-in-progress is covered with a soft material and assembled. The surfaces of the outer layer pipe material 301 and the inner layer pipe material 302 are cleaned, and the work-in-progress is covered with a soft material and assembled in the following order: outer layer pipe material 301 is placed on the outside and inner layer pipe material 302 is placed on the inside. A coating gap 304 is placed between the outer layer pipe material 301 and the inner layer pipe material 302. Sealing and welding are performed using two positioning rings 303, and then a vacuum is drawn. Then, the production of the coated work-in-progress 3 is completed in advance.

Step S2 is heating by electromagnetic induction. The core rod transport car 1 and the core rod 2 are connected, and the core rod 2 passes through the pre-coated workpiece 3. To heat it, both are sent to the electromagnetic induction heating device 4 at a speed v = 400 mm/s using the core rod transport car 1, and the heating power and frequency are adjusted. When the pre-coated workpiece 3 leaves the electromagnetic induction heating device 4, the surface to be combined in the outer layer pipe material 301 is heated to the target temperature T = 850 ° C., and when the target temperature T is reached, the pre-coated workpiece 3 is sent to the gradual tilt rolling device 5 via the core rod 2 for rolling.

Step S3 is to gradually incline and roll the composite. The roll 501 and the spacing plate 502 of the gradually incline rolling machine 5 are adjusted, the target hole shape is set to be D = 64 mm, the gradually incline rolling machine 5 is started, and the core rod 2 and the pre-coated workpiece 3 are sent to the gradually incline rolling machine 5 using the core rod transport car 1, and the pre-coated workpiece 3 is sent to the roller gap surrounded by the core rod 2, the roll 501 and the spacing plate 502 to gradually perform incline rolling and compounding, and the diameter gradually decreases and the wall gradually becomes thinner through the entrance circular corner region 5011, the entrance cone region 5012, the gradual wall reduction region 5013, the finishing region 5014, the exit circular cone region 5015 and the exit circular corner region 5016, and the composite interface is metallurgically bonded. Finally, the rolled composite thin-walled tube is obtained and sent through the feed track 6.

Step S4 controls the heat treatment. The final rolled composite thin-walled tube is cut to a specified size after removing the leading and trailing ends, and the tube is subjected to heat treatment to obtain the target structural properties, resulting in a finished composite thin-walled tube.

By locally remelting at the composite interface, a composite thin-walled tube made of 6061 aluminum alloy and 316L stainless steel with a large length-to-diameter ratio is produced.

The outer layer pipe material 301 is a 6061 aluminum alloy thin-walled pipe material with an outer diameter of 80 mm, a wall thickness of 4.4 mm, a length of 8000 mm, and a melting point of 607-650°C. The inner layer pipe material 302 is a 316L stainless steel thin-walled pipe material with an outer diameter of 70 mm, a wall thickness of 2 mm, and a length of 8000 mm. The coating gap 304 between the outer layer pipe material 301 and the inner layer pipe material 302 is 0.6 mm. The electromagnetic induction heating device 4 is a digital electromagnetic heater that is only applicable to steel. It has no significant heating effect on aluminum and its alloys. It also has its own protection function and the maximum heating temperature is 1600°C. The core rod 2 is 10000 mm long and 58 mm in diameter.

The dimensions of the progressively tilted rolling device 5 are as follows: the entrance angular region 5011 is an arc with a radius r = 5 mm and a length L1 equal to r, the entrance cone region 5012 has a length L2 = 60 mm and a cone angle α2 = 2°. The gradual thickness reduction region 5013 has a length L3 = 120 mm, is 30-50% of the length of the conical rolling roll, and includes only eight identical strong thickness reduction regions 50131 and only eight identical weak thickness reduction regions 50132, the strong thickness reduction region 50131 has a cone angle α31 = 12° and a length L31 = 5 mm, the weak thickness reduction region 50132 has a cone angle α32 = 2° and a length L32 = 10 mm, the finishing region 5014 has a length L4 = 70 mm and a cone angle α4 = 0°, the exit cone region 5015 has a length L5 = 25 mm and a cone angle α5 = 1°, and the exit circular corner region 5016 is an arc with a radius r = 5 mm and a length L6 equal to r.

The production steps are as follows:

In step S1, the work-in-progress is covered with a soft material and assembled. The surfaces of the outer layer pipe material 301 and the inner layer pipe material 302 are cleaned. The work-in-progress is covered with a soft material and assembled in the order of the outer layer pipe material 301 on the outside and the inner layer pipe material 302 on the inside. A coating gap 304 is placed between the outer layer pipe material 301 and the inner layer pipe material 302. Sealing and welding are performed using two positioning rings 303, and then a vacuum is drawn. Then, the production of the coated work-in-progress 3 is completed in advance.

Step S2 is heating by electromagnetic induction. The core rod transport car 1 and the core rod 2 are connected, and the core rod 2 passes through the pre-coated workpiece 3. To heat it, the core rod transport car 1 is used to send it to the electromagnetic induction heating device 4 at a speed v = 800 mm/s, and the heating power and frequency are adjusted. When the pre-coated workpiece 3 leaves the electromagnetic induction heating device 4, the surface to be combined in the inner layer pipe material 302 is heated to the target temperature T = 700 ° C., which is higher than the melting point temperature of the outer layer pipe material 301. When the target temperature T is reached, the pre-coated workpiece 3 is sent to the gradual tilt rolling device 5 via the core rod 2 and rolled.

Step S3 is to gradually perform tilt rolling and compounding. The rolling roll 501 and the spacing plate 502 of the gradual tilt rolling equipment 5 are adjusted, the shape of the target hole is set so that the shape D = 64 mm, the gradual tilt rolling equipment 5 is started, and the core rod 2 and the pre-coated workpiece 3 are sent together to the gradual tilt rolling equipment 5 using the core rod transport car 1, and the pre-coated workpiece 3 is sent to the roller gap surrounded by the core rod 2, the rolling roll 501 and the spacing plate 502, and gradually perform tilt rolling and compounding. When the surfaces of the outer layer pipe material 301 and the inner layer pipe material 302 to be combined are in contact, the target temperature T of the inner layer pipe material 302 is higher than the melting point temperature of the outer layer pipe material 301, so that the surface of the inner layer pipe material 302 to be combined will melt locally again, and the diameter will gradually decrease and the wall will gradually become thinner through the entrance circular corner region 5011, the entrance cone region 5012, the gradual wall reduction region 5013, the finishing region 5014, the exit cone region 5015 and the exit circular corner region 5016, thereby realizing the metallurgical bonding of the composite interface. Finally, the rolled composite thin-walled tube is obtained and sent through the feed track 6.

Step S4 controls the heat treatment. The leading and trailing ends of the final rolled composite thin-walled tube are removed, the tube is cut to a specified size, and the tube undergoes heat treatment to obtain the target structural properties, resulting in a finished composite thin-walled tube.

The above describes and illustrates the main features and advantages of the present invention. It is obvious to one skilled in the art that the present invention is not limited to the details of the exemplary embodiment described above, and other specific forms of the present invention may be realized without departing from the spirit and basic spirit of the present invention. Therefore, in any case, the embodiment should be regarded as illustrative and not restrictive. The scope of the present invention is limited by the appended claims, not the above description, and all changes within the meaning and scope of the claims that are equivalent to the scope of the claims are also included in the present invention.

It should be understood that, although the present specification has been described according to the embodiments, each embodiment does not include only one independent technical means, and this description form in the specification has merely been made clear, and that a person skilled in the art may obtain other embodiments that are understandable to him/her by appropriately combining the technical means in each example, taking the specification as a whole.

REFERENCE SIGNS LIST 1 Core rod transport vehicle 2 Core rod 3 Pre-coated work-in-progress 4 Electromagnetic induction heating device 5 Progressive tilt rolling equipment 6 Feeding track 301 Outer layer pipe material 302 Inner layer pipe material 303 Positioning ring 304 Coating gap 501 Rolling roll 502 Spacing plate 5011 Entrance corner region 5012 Entrance cone region 5013 Progressive wall thickness reduction region 5014 Finishing region 5015 Exit cone region 5016 Exit corner region 50131 Strong wall thickness reduction portion 50132 Weak wall thickness reduction portion

Claims (5)

The present invention includes a core rod transport vehicle (1), a core rod (2), a pre-coated workpiece (3), an electromagnetic induction heating device (4), a progressive tilt rolling device (5), and a feed track (6) arranged in sequence along a rolling axis;
The core rod transport vehicle (1) is for interlocking the core rod (2) so that it moves back and forth along the rolling axis, the pre-coated workpiece (3) coats the core rod (2), the electromagnetic induction heating device (4) is installed at the entrance side of the progressive tilt rolling equipment (5) and for heating the pre-coated workpiece (3) immediately before it enters the progressive tilt rolling equipment (5), the progressive tilt rolling equipment (5) is for rolling the pre-coated workpiece (3), the feed track (6) is installed at the exit of the progressive tilt rolling equipment (5) and for feeding the pre-coated workpiece (3) that has been rolled and combined, the progressive tilt rolling equipment (5) including rolling rolls (501) and spacing plates (502),
The rolling roll (501) is a conical rolling roll consisting of an entrance corner region (5011), an entrance cone region (5012), a gradual thickness reduction region (5013), a finishing region (5014), an exit cone region (5015) and an exit corner region (5016) which are sequentially arranged along the rolling axis direction, and the gradual thickness reduction region (5013) consists of only N strong thickness reduction portions (50131) and weak thickness reduction portions (50132) which are arranged alternately,
The entrance cone region (5012) has a length L2 of 20% to 40% of the length of the rolling roll (501) and a cone angle α2 of 2° to 6°, the finishing region (5014) has a length L4 of 20% to 40% of the length of the rolling roll (501) and a cone angle α4 of 0° to 1°, the exit cone region (5015) has a length L5 of 5% to 15% of the length of the rolling roll (501) and a cone angle α5 of 0° to 2°,
The gradual thickness reduction region (5013) has a length L3 of 30% to 50% of the length of the rolling roll (501), and the cone angle α31 of the strong thickness reduction portion (50131) is 10° to 20°, and the cone angle α32 of the weak thickness reduction portion (50132) is 1° to 10°, and the length L32 of the weak thickness reduction portion (50132) is 2 to 10 times the length L31 of the strong thickness reduction portion (50131).
1. A composite apparatus for progressively tilt rolling composite thin-walled tubes made of dissimilar metals with a large length-to-diameter ratio, comprising: The entrance circular corner region (5011) is an arc having a radius of r, and both ends of the arc are in contact with the entrance end face of the rolling roll (501) and the conical surface of the entrance cone region (5012), respectively, and the length L1 is equal to r, and r is equal to 1% to 4% of the outer diameter of the finishing region (5014);
2. A composite apparatus for progressively tilt rolling composite thin-walled tubes made of dissimilar metals with a large length-to-diameter ratio as claimed in claim 1. The exit circular corner region (5016) is an arc having a radius of r, and both ends of the arc are in contact with the exit end face of the rolling roll (501) and the conical surface of the exit conical region (5015), respectively, and the length L6 is equal to r, and r is 1% to 4% of the outer diameter of the finishing region (5014).
2. A composite apparatus for progressively tilt rolling composite thin-walled tubes made of dissimilar metals with a large length-to-diameter ratio as claimed in claim 1. Step S1 of covering the work-in-progress with a flexible material and assembling the work-in-progress, in which the surfaces of the outer layer pipe material (301) and the inner layer pipe material (302) are cleaned, and the work-in-progress is covered with a flexible material and assembled in the order of placing the outer layer pipe material (301) on the outside and the inner layer pipe material (302) on the inside, and a covering gap (304) is placed between the outer layer pipe material (301) and the inner layer pipe material (302), and sealing and welding are performed using two positioning rings (303), followed by vacuum drawing, thereby completing the production of the covered work-in-progress (3) in advance;
Step S2 of heating by electromagnetic induction, in which the core rod transport car (1) and the core rod (2) are connected, the core rod (2) passes through the pre-coated workpiece (3), and is sent to the electromagnetic induction heating device (4) together with the core rod transport car (1) at a speed v for heating, and the heating power and frequency are adjusted, so that when the pre-coated workpiece (3) leaves the electromagnetic induction heating device (4), the surfaces to be combined on the outer layer pipe material (301) and/or the inner layer pipe material (302) are heated to a target temperature T, and when the target temperature T is reached, the pre-coated workpiece (3) is sent to the gradual tilt rolling device (5) via the core rod (2) for rolling and combining;
In step S3 of gradually tilt rolling and combining, the rolling rolls (501) and spacing plates (502) of the gradually tilt rolling machine (5) are adjusted, the shape of the target hole and the shape D are set, the gradually tilt rolling machine (5) is started, the core rod (2) and the pre-coated workpiece (3) are sent together to the gradually tilt rolling machine (5) by the core rod transport car (1), and the pre-coated workpiece (3) is rolled into the rod (5) surrounded by the core rod (2), the rolling rolls (501) and the spacing plates (502). Step S3: The thin-walled tube is fed into the roller gap for gradually performing inclined rolling and compounding, and passes through an entrance corner region (5011), an entrance cone region (5012), a gradual wall reduction region (5013), a finishing region (5014), an exit cone region (5015), and an exit corner region (5016), where the diameter is gradually reduced, the wall is gradually thinned, and the composite interface is bonded by metallurgy. Finally, a composite thin-walled tube is obtained by rolling, and then the tube is fed through the feed track (6);
and a step S4 of controlling the heat treatment, in which the head and tail of the finally rolled composite thin-walled tube are removed, cut according to a predetermined size, and subjected to heat treatment to obtain a target structure performance to obtain a finished composite thin-walled tube.
A composite method comprising: In step S3, when the inclined rolling and the combination are gradually performed, the diameter reduction amount is greater than 20% of the outer diameter of the coated workpiece (3), the wall thickness reduction amount is greater than 40% of the entire wall thickness of the coated workpiece (3), and the degree of wall non-uniformity is less than or equal to 5%.
5. The method of claim 4.