US20200384518A1

US20200384518A1 - Manufacturing device and method for bimetal composite hollow billet

Info

Publication number: US20200384518A1
Application number: US16/863,421
Authority: US
Inventors: Zhiyong Zhang; Kechuan WANG; Gaofeng SUN
Original assignee: TAIYUAN PLS TECHNOLOGY DEVELOPMENT Co Ltd
Current assignee: TAIYUAN PLS TECHNOLOGY DEVELOPMENT Co Ltd
Priority date: 2019-06-10
Filing date: 2020-04-30
Publication date: 2020-12-10
Also published as: CN110293149A; CN110293149B

Abstract

A manufacturing device for a bimetal composite hollow billet, includes a mandrel, a frame, a planetary carrier rotatably disposed on the frame, a plurality of rolls rotatably disposed on the planetary carrier, and disposed around the mandrel, and a bimetallic pipe to be processed is sleeved on the mandrel.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 USC 119 (a) of Chinese Patent Application No. 201910494890.9 filed on Jun. 10, 2019 in the State Intellectual Property Office of the People's Republic of China, the entire disclosure of which is incorporated herein by reference for all purposes.

BACKGROUND

1. Field

The following description relates to the technical field of metallurgical bonding manufacturing of bimetal composite pipes, and in particular, to a manufacturing device and method for a bimetal composite hollow billet.

2. Description of Related Art

A bimetal composite hollow billet is a pipe composed of two different metal materials, with a carbon steel pipe or an alloy steel pipe as a base layer pipe, and cladded or lined with a certain thickness of special alloy on an inner surface or an outer surface. Pipe layers are tightly bonded through various deformation and connection techniques, so that the two materials are integrally bonded. A general design principle of the pipe is that a base material meets an allowable stress of pipe design, and a clad layer meets the requirements of various complicated working conditions. However, for some special operation scenarios, such as high temperature and high pressure conditions, two metals with different properties must have a firm metallurgical bond at an interface. In this way, the two metals can meet many performance requirements such as high strength, corrosion resistance and high temperature resistance that a single metal cannot meet, and to ensure the safety and reliability of the composite pipe used in harsh environments.
The mechanism of bimetallic cladding is complex. Although experts and scholars have done a lot of research, only a small part of the mechanism has been revealed at present. The following are some theories studied and proposed by scholars:
Metal bond theory: Proposed by N.S. Buton from a chemical perspective in 1954. Two metals are close to each other, and atoms in them are attracted to each other, thereby promoting metal cladding.
Thin film theory: the cladding property of a bimetallic material depends on the surface state of metallic materials. A surface oxide film and an oil film of double metals are removed for consistent plastic deformation, and when the double metals are close to a certain range referring to an action range of a force between atoms, the double metals can be bonded.
Energy theory: Proposed by A.II. Simeonov in 1958. The theory believes that what really promotes the bonding between metals is the energy of the metal atoms themselves.
Recrystallization theory: Proposed by L.N. Parkes proposed in 1953. Metals are deformed under the action of a high temperature, and at the same time, because the deformation causes cold work hardening, lattice atoms on a metal contact surface are recombined to form a common crystal grain, thereby achieving metal cladding.
Diffusion theory: Proposed by Kazakov in the 1970s. When double metals are heated to near their melting temperatures, an inter-diffusion layer appears in an area where the double metals contact each other, and it is precisely the diffusion area that promotes the bonding between the double metals.

SUMMARY

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
In one general aspect, a manufacturing device for a bimetal composite hollow billet, includes a mandrel, a frame, a planetary carrier rotatably disposed on the frame, a plurality of rolls rotatably disposed on the planetary carrier, and disposed around the mandrel, and a bimetallic pipe to be processed is sleeved on the mandrel.
A roll of the plurality of rolls may include a thread section, a flattening section, and a rounding section that are sequentially disposed.
The roll and the mandrel may have a first non-zero angle therebetween.
The thread section may include a tapered thread disposed on an outer wall of the roll.
A larger end of the tapered thread may face the flattening section.
The mandrel may be provided with a guide section protruding outward, the guide section may be parallel to the thread section, and the guide section may be located directly below the thread section.
A rotation direction of the planetary carrier may be opposite to a rotation direction of the plurality of rolls.
The bimetallic pipe may be a preformed bimetallic sleeve pipe blank.
The preformed bimetallic sleeve pipe blank may be manufactured by heating the preformed bimetallic sleeve pipe blank above a recrystallization temperature, sleeving the heated preformed bimetallic sleeve pipe blank on the mandrel, and starting the planetary carrier and the plurality of rolls for rolling.
The preformed bimetallic sleeve pipe blank may include an external layer composite pipe and an internal layer base pipe disposed coaxially, and a wall thickness of the external layer composite pipe may be 26%-28.4% of a wall thickness of the internal layer base pipe.
In another general aspect, a manufacturing method for a bimetal composite hollow billet, includes: heating a preformed bimetallic sleeve pipe blank above a recrystallization temperature; sleeving the heated preformed bimetallic sleeve pipe blank on the mandrel; and starting the planetary carrier and the plurality of rolls for rolling.
The preformed bimetallic sleeve pipe blank may include an external layer composite pipe and an internal layer base pipe disposed coaxially; a wall thickness of the external layer composite pipe may be 26%-28.4% of a wall thickness of the internal layer base pipe.
The preformed bimetallic sleeve pipe blank may be formed by a manufacturing device including a mandrel, a frame, a planetary carrier rotatably disposed on the frame, a plurality of rolls rotatably disposed on the planetary carrier, and disposed around the mandrel, and the preformed bimetallic sleeve pipe blank to be processed may be sleeved on the mandrel.
A roll of the plurality of rolls may include a thread section, a flattening section, and a rounding section that are sequentially disposed.
The roll and the mandrel may have a first non-zero angle therebetween.
The thread section may include a tapered thread disposed on an outer wall of the roll.
A larger end of the tapered thread may face the flattening section.
The mandrel may be provided with a guide section protruding outward, the guide section may be parallel to the thread section, and the guide section may be located directly below the thread section.
A rotation direction of the planetary carrier may be opposite to a rotation direction of the plurality of rolls.
Other features and aspects will be apparent from the following detailed description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of an example of a manufacturing device and method for a bimetal composite hollow billet.

FIG. 2 is a schematic structural diagram of an example of a working condition of a manufacturing device and method for a bimetal composite hollow billet.

Throughout the drawings and the detailed description, the same reference numerals refer to the same elements. The drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be apparent after an understanding of the disclosure of this application. For example, the sequences of operations described herein are merely examples, and are not limited to those set forth herein, but may be changed as will be apparent after an understanding of the disclosure of this application, with the exception of operations necessarily occurring in a certain order. Also, descriptions of features that are known in the art may be omitted for increased clarity and conciseness.
The features described herein may be embodied in different forms, and are not to be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many possible ways of implementing the methods, apparatuses, and/or systems described herein that will be apparent after an understanding of the disclosure of this application.
The terminology used herein is for describing various examples only, and is not to be used to limit the disclosure. The articles “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “includes,” and “has” specify the presence of stated features, numbers, operations, members, elements, and/or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, members, elements, and/or combinations thereof.
Existing manufacturing processes of bimetal composite hollow billets are divided into plastic clad forming and non-plastic clad forming processes.

I. Plastic Clad Forming Process

Plastic clad forming is a cladding process that utilizes a local or overall plastic deformation of a pipe to achieve a close bond between an internal layer pipe and an external layer pipe.

1. There is a gap between the internal layer pipe and the external layer pipe at the beginning.
2. Deformation stage of the internal layer pipe: After a loading pressure is applied to an inner wall of the internal layer pipe, the wall of the internal layer pipe is radially expanded until an outer surface of the internal layer pipe is in direct contact with an inner surface of the external layer pipe and the gap is eliminated. At this time, no contact pressure occurs, but the internal layer pipe has met a yield condition.
3. Cladding stage: As the loading pressure continues to increase, a loading process of the external layer pipe begins. The external layer pipe first expands elastically. After the inner surface of the external layer pipe meets the yield condition, the external layer pipe is partially plastically expanded to reach a maximum loading pressure.
4. Unloading stage: the loading pressure is gradually reduced from maximum to zero; at this time, the internal pipe and the external pipe are both in an unloading state. Due to the plastic deformation of the internal layer pipe in the second stage, when the loading pressure is completely eliminated, the internal and the external layer pipes are still in contact, resulting in a residual contact pressure.

During the plastic cladding process, the internal layer pipe is completely plastically deformed, and the external layer pipe is in an elastic deformation state or a partial plastic deformation state. After unloading, because a springback amount of the external layer pipe is greater than a springback amount of the internal layer pipe, the external layer pipe clamps the internal layer pipe tightly. Thus, the two pipes form an expansion force, that is, a residual contact pressure, thereby achieving a close mechanical bond.
The magnitude of the residual contact pressure depends on the springback capacity of the material. Under a high temperature condition, the greater the amount of plastic deformation between the pipe layers during the cladding stage, the easier a diffusion reaction to occur at a bonding interface to achieve metallurgical bonding at the interface.
According to different states, plastic clad forming can be divided into cold forming and hot forming processes.

(I) Cold Forming Process

A basic characteristic of the cold forming manufacturing process is that a prefabricated thin-walled clad layer (for example, a stainless steel pipe) is nested into a base layer (for example, a carbon steel pipe). Then, through a mechanical method, the internal layer pipe is plastically deformed to overcome a gap at a bonding interface. At the same time, the external layer pipe is also deformed with a certain amount of elasticity. When an external force is removed, the elastic deformation of the external layer pipe is recovered, so that an inner wall of the external layer pipe fits tightly on an outer wall of the internal layer pipe.
The cold forming process can be divided into an external reducing type (for example, a mechanical drawing method) and an internal expanding type (for example, spin forming, and hydraulic pressure, etc.).

1. In the mechanical drawing method, after an external pipe and an internal pipe are sleeved, the internal pipe is extruded to deform plastically during a drawing process through a die with a certain tapered hole or an extrusion die placed in the internal pipe. A side of the external pipe is simultaneously elastically deformed and partially plastically deformed. After the drawing process is finished, the external pipe is subjected to an internal restoring force to exert an internal compressive stress on the internal pipe, so that walls of the internal and external pipes are closely bonded.
2. The mechanical drawing method is suitable for almost all internal and external pipe materials, but the bonding strength is not high, and the pipes are easy to debond at a high temperature. In addition, a wall thickness of the composite pipe may fluctuate to form a nodular crack on the surface of the pipe, and as a great friction is generated during the drawing process, the calculation of a drawing force is not easy.

(1) Spin Forming Method

At present, the spin forming method is a main process for domestic production of composite pipes with a stainless steel internal layer pipe. The spin forming method can produce an internally cladded composite pipe with better strength than the mechanical drawing method. Industrial composite pipes with a stainless steel internal clad layer are mainly used in the fields of water supply, heating, gas supply, food, pharmacy, fire protection and central air conditioning. Composite pipes with a corrosion-resistant alloy internal clad layer fabricated by the spin forming process also have some applications in the petrochemical industry.
Before spinning, there is a gap between an internal layer pipe and an external layer pipe of a stainless steel lined composite pipe. After a spinning die applies a pressure to an inner wall of the internal pipe, the diameter of the internal pipe is expanded radially until an outer surface of the internal pipe just contacts an inner surface of the external pipe and the gap is eliminated.
As the spinning die continues to increase the pressure on the internal layer pipe, the pressure is transmitted to the external base pipe through the internal layer pipe, and the external base pipe begins to expand radially. Due to the plastic deformation of the internal layer pipe, when the pressure is completely removed, the internal and external pipes are still in contact to produce a contact pressure. At this time, the external pipe is elastically deformed and returns to an original state. The internal and external layers are bonded with a distance of 5-25 μ, and are in an interference fit state, with a crisp percussion sound.
The stainless steel lined composite pipe produced by the spin forming method has the following characteristics:

1) The pipe has high interface strength (compared to the drawing process), strong extrusion resistance and resonance resistance. The method greatly reduces the possibility of water pipe leakage caused by an external force impact, thereby avoiding a large amount of waste of a water resource due to leakage.
2) Compared with the drawing process, the wall of the composite pipe produced by the spin forming method is smooth and uniform, and does not scale; the diameter is guaranteed, and energy consumption is low.
3) The pipe is connected by using a traditional technique, and is safe, flexible and reliable.
4) Heat energy loss is reduced; the heat preservation performance of the stainless steel pipe is 24 times that of a copper material water pipe, which greatly saves the heat energy loss in hot water transportation.
5) Cost-effective: the total cost is only 50% the price of a thin-walled stainless steel pipe and 20% the price of a copper pipe.

(2) Hydraulic Forming Method

The principle of hydraulic forming is basically the same as the principle of spin forming, except that a high-pressure liquid is used for exerting a pressure in the pipe instead of rotary extrusion by a spinning tool, as shown in FIG. 1. An internal layer pipe and an external layer pipe are expanded together by a water pressure. Because the external layer pipe is usually more elastic, after the pressure is released, the internal layer pipe is placed under a residual compressive stress, and a safe mechanical interference fit is created between the internal and external layer pipes.
By comparing the two forming methods, for spin forming, the size of the internal pressure is difficult to determine, under pressure or over pressure is prone to occur, and multiple spins are likely to cause cracking of the internal clad layer. For hydraulic forming, the internal pressure is uniform, and the size can be calculated. In addition, the inner wall surface of the composite pipe produced by hydraulic forming is free from abrasion and damage, and no work hardening occurs. Therefore, hydraulic forming is more excellent. However, the two forming methods have a common weakness that the internal and external layers are only mechanically bonded, and will debond and fail due to stress relaxation under a high-temperature environment, like that occurring in drawing forming.

(3) Adhesion +Hydraulic Forming Method

That is, a special adhesive is used between an external base layer pipe of a mechanical lining and an internal pipe of a corrosion-resistant clad layer based on the original hydraulic forming process, making an interface of a composite pipe bonded more reliably.
To sum up, the cold forming process mainly has the following characteristics:
Advantage: the production process is relatively simple.
Disadvantages:

1) the two metal layers are not metallurgically fused, but only closely fit relying the cold working of the internal and external layers; under the condition of an axial force, the internal and external metal layers are difficult to transmit and balance the external force;
2) if the cold-worked composite pipe encounters a high temperature, the composite pipe will have a tendency to debond, and will fail due to stress release; and
3) in applications requiring heat transfer, the heat resistance will increase significantly due to the gap between the internal and external metal layers.

Due to the inevitable disadvantages of the cold forming process, the usage environment and application fields of cold-worked pipes are limited.
(II) Hot Forming Process
The hot forming manufacturing process includes two methods: hot rolling and hot extrusion. The former is mainly applicable to the production of seamed composite pipes, and the latter is applicable to the production of seamless composite pipes.

(1) Hot rolling forming method of clad sheet

Rolling is a traditional method for preparing clad metals. Hot-rolled cladding is essentially pressure welding. If the amount of deformation is large enough, the pressure applied by a roll will destroy an oxide film on a metal surface, bringing surfaces into an atomic contact, and welding the two surfaces together. Advantages: the method has high productivity, good quality, and low cost, and can greatly save the loss of a metal material. Therefore, the method is currently a widely used clad material production technology. Rolled clad sheets account for 90% of total clad sheet output. Hot-rolled clad sheets are often used to produce straight-welded pipes with a wall thickness of less than 32 mm. Disadvantages: One-time investment is large, and many material combinations cannot be achieved by rolling cladding.

(2) Hot extrusion forming method

Hot extrusion is generally performed on a bimetallic pipe blank, and is called clad extrusion. It is the best method for producing seamless stainless steel and high-nickel alloy seamless composite pipes.
Clad extrusion has the following advantages: the interface is metallurgically bonded; the force involved in the extrusion process is completely a compressive stress. Therefore, the method is particularly suitable for the working of a high-alloy metal with poor hot workability and low plasticity.
The disadvantage is that because the bonding is determined by the diffusion of an element on the interface in a very short time during the extrusion process, it is often affected by the presence of an oxide film. Therefore, clad extrusion is currently limited to cladding between carbon steel, stainless steel and high-nickel alloys.
II. Non-Plastic Clad Forming
(1) Overlay welding cladding method
Overlay welding is an earlier method for making clad metals. It is a process of depositing a metal layer with a specific property on the surface of a workpiece by methods such as fusion welding, brazing, thermal spraying, and laser cladding. Overlay welding includes hard overlay welding and metal spraying. The former refers to the use of a melting technology to deposit another layer of metal on a metal surface, and the latter is to deposit a fine metal particle on a metal surface. Many overlay welding methods can be used to prepare a clad metal, but various fusion welding methods account for the largest proportion of overlay welding. In the narrow sense, overlay welding refers to fusion welding.
The main disadvantages of overlay welding for manufacturing composite pipes are: the cost is too high for large-area overlay welding, and the combination of materials that can be produced is limited to compatible materials under fusion welding. For example, two materials with very different melting points cannot be cladded, and materials that produce a brittle intermetallic compound during welding cannot be cladded. At present, it is generally difficult to achieve internal deposition of pipes with a diameter smaller than 4″.
Advantages: the interface is firmly bonded, and the clad layer can be made of some difficult-to-deform metal materials.
(2) Explosive cladding method
The explosive cladding process relies on a shock wave generated by the explosion of an explosive to plastically deform an internal pipe to close to an external pipe, so as to form a composite pipe. By explosive forming, a clad layer can be less than 0.2 mm. In addition, explosive welding can be used to achieve connection of a variety of metals, and some clad layer materials cannot be achieved by other methods. Advantages: one-time instant forming, simple process, and basically the same pressure generated by the explosion of the explosive at each point. Disadvantages: Due to the irregularity of an inner surface of a base layer and an outer surppface of an internal clad layer and the unevenness of a wall thickness, the formed composite pipe has a small bonded area. The interface is non-diffusively metallurgically bonded. The explosive amount of a long composite pipe is difficult to accurately determine, although the control of explosive amount has a certain impact on the full plastic deformation of the internal liner pipe, and has a certain risk.
(3) Centrifugal casting method
The centrifugal casting method is suitable for manufacturing a composite pipe with a melting point of a lined metal lower than that of an external layer metal. A clad layer and a base layer are both made of a liquid metal. First, a molten steel for preparing the external pipe is introduced into a rotating metal die. The temperature inside the pipe is monitored during the solidification of the external pipe. When the external pipe is solidified and reaches a certain temperature, an internal layer metal, like a corrosion-resistant alloy, is poured. In this way, a bimetal composite hollow billet with a firm metallurgical bond can be produced. Advantages: An interface is metallurgically bonded, and the composite pipe has high density, and good slag and gas removal performance. Disadvantages: The method is limited to as-cast use if there is no subsequent thermal deformation. Due to a coarse as-cast structure, the mechanical properties of each layer of metal cannot be fully played. In addition, this method cannot produce a clad steel pipe with a light alloy external layer.
(4) Centrifugal casting+hot extrusion (hot extrusion+cold rolling) method
“Centrifugal casting+hot extrusion” is a short-flow composite pipe preparation method. A clad hollow billet is produced by centrifugal casting. Then, the clad hollow billet is subjected to the procedures of heating, hot extrusion or hot extrusion+cold rolling, and a subsequent heat treatment to obtain a final composite pipe. This method effectively combines the advantages of the two methods of centrifugal casting and hot extrusion. It shortens the production process, realizes a complete metallurgical bond of a clad interface, and overcome the defects of a metal as-cast structure. Its uniqueness lies in the combination of a primary industrial material with a high-tech metallurgical process. A plastic thermal clad technology, for example, centrifugal casting, and hot extrusion, etc. and a cold rolling (or cold drawing) production method are used to obtain a high-quality composite pipe.
(5) Centrifugal thermite method
The centrifugal thermite method is also called a self-propagating high temperature synthesis (SHS) centrifugation method. The essence of the centrifugal thermite method is to cause a thermite reaction in a centrifugal force field. The so-called thermite reaction is that a metal aluminum powder and other metal oxide powder are uniformly mixed, and are ignited to cause a very rapid exothermic reaction (MO+Al→M+Al₂O₃+Q). An adiabatic temperature of the reaction can be close to 2727° C. (3000 K), so the products are all in a liquid state. Under the action of a centrifugal force, high-density products such as Fe, Cr and Ni are concentrated near an inner wall of a carbon steel pipe to form an internal clad layer. Al₂O₃forms an innermost residue, which is removed by a mechanical method, thereby preparing a bimetal composite steel pipe.
(6) Powder metallurgy method
A powder filled layer is added between a main pipe made of carbon steel or a similar material and a thin-walled metal pipe. The pipes are sealed at both ends with a bottom plate. They are heated at a predetermined temperature, and hot-extruded into a clad steel pipe. Finally, the bottom plate and the thin-walled metal pipe are removed by pickling. Depending on the application, a clad layer can be an external layer or an internal layer.
(7) Electromagnetic forming method
The electromagnetic forming process belongs to the field of high-energy working. It uses a transient high-voltage pulsed magnetic field to force a metal to plastically deform. When a high-voltage direct current charges a high-voltage pulse capacitor and the voltage reaches a critical breakdown voltage of an isolating switch, an isolation gap is broken down. The capacitor adds all the stored energy to a coil. A very large current passes through the coil in a few microseconds, producing a strong pulsed magnetic field in an instant. A pipe metal placed outside the coil will induce a current in an opposite direction, and a generated reverse magnetic flux prevents a magnetic flux from passing through the pipe metal, forcing magnetic field lines to be dense in a gap between the coil and the pipe metal. The dense magnetic field lines have an expansion property, which makes each part of the surface of the pipe metal subjected to a huge impact pressure to collide with a die or another pipe within a few microseconds. In this way, a plastic flow is caused at a bonding interface to form a metallurgical bond.
The electromagnetic forming method has high efficiency and safety, and can connect two metals with very different properties. However, limited to its special process, at present, the method is only suitable for processing materials with low strength and good electrical conductivity, such as copper and aluminum.
Status of forming methods for metallurgically bonded bimetal composite hollow billets
At present, the commonly used forming methods for metallurgically bonded bimetal composite hollow billets with good overall mechanical properties in the industry are generally divided into the following four types:

1. Rolling cladding method: A preformed composite pipe blank is heated above a recrystallization temperature, and the pipe blank is rolled by using a rolling mill. A plastic deformation occurs in a cross section of the pipe blank, and under a compressive load, a bimetallic interface forms a close fit (a sufficient pass reduction is required). After rolling, the waste heat can diffuse atoms between double metals, thereby forming a metallurgical bond on the bimetallic interface (the bimetallic interface should have a large enough contact area).
2. Explosive cladding method: A composite pipe is produced by using an explosive welding and cladding process. Two metals are welded into one by an explosive which releases energy to form a metallurgical bond.
3. Explosive+rolling cladding method: First, a composite pipe blank with a relatively high thickness is obtained by the explosive cladding method. Then, different requirements and conditions are distinguished, and a composite pipe that meets a required wall thickness is prepared by cold rolling or hot rolling.
4. Centrifugal casting+rolling clad method: First, a composite pipe blank in which two metals are metallurgically bonded is obtained by the centrifugal casting method. Then, a composite pipe is prepared by a cold rolling or hot rolling procedure, which has no defect in a cast structure and meets a required wall thickness.

The four cladding methods above all have obvious shortcomings.
To solve the above technical problems, the present disclosure provides a manufacturing device and method for a bimetal composite hollow billet, which can firmly bond internal and external layers of metals, have a bonding surface which can bear an axial force, and is clean, free from an oxide layer or a cavity.
To achieve the above objective, the present disclosure provides the following solutions.
The present disclosure provides a manufacturing device and method for a bimetal composite hollow billet, including a frame, a planetary carrier, a plurality of rolls and a mandrel, where the planetary carrier is rotatably disposed on the frame; the plurality of rolls are rotatably disposed on the planetary carrier, and the plurality of rolls are disposed around the mandrel; a bimetallic pipe to be processed is sleeved on the mandrel.
Optionally, a roll includes a thread section, a flattening section, and a rounding section that are sequentially disposed.
Optionally, the roll and the mandrel have a first included angle therebetween.
Optionally, the thread section includes a tapered thread disposed on an outer wall of the roll.
Optionally, a larger end of the tapered thread faces the flattening section.
Optionally, the mandrel is provided with a guide section protruding outward; the guide section is parallel to the thread section, and the guide section is located directly below the thread section.
Optionally, a rotation direction of the planetary carrier is opposite to a rotation direction of the plurality of rolls.
The present disclosure further discloses a manufacturing method using the manufacturing device for a bimetal composite hollow billet, including the following steps:

step 1, heating a preformed bimetallic sleeve pipe blank above a recrystallization temperature;
step 2, sleeving the heated preformed bimetallic sleeve pipe blank on the mandrel; and
step 3, starting the planetary carrier and the plurality of rolls for rolling.

Optionally, the preformed bimetallic sleeve pipe blank includes an external layer composite pipe and an internal layer base pipe disposed coaxially; a wall thickness of the external layer composite pipe is 26%-28.4% of a wall thickness of the internal layer base pipe.
Compared with the prior art, the present disclosure achieves the following technical effects:
In the present disclosure, the manufacturing device and method for a bimetal composite hollow billet plastically deform the heated preformed bimetallic sleeve pipe blank through the thread section, form a thread groove on the surface of the external composite pipe and a bimetallic interface, cause a secondary plastic deformation under the action of the guide section on the mandrel, then flatten and reduce a diameter of the thread groove in the flattening section of the roll, and re-round by the rounding section.
In the present disclosure, the manufacturing method for a bimetal composite hollow billet causes a severe plastic deformation of the bimetallic interface, increases a bonded area between metals on the interface, and promotes the cracking of an oxide layer on the surface of the metals on the interface. Under the action of rolling waste heat, metal atoms on the interface diffuse into each other to form a bimetal composite hollow billet with a firm metallurgical bond, and then hot or cold rolling is performed to produce different specifications of finished bimetal composite pipes with a reinforced metallurgical bond.
Description of reference numerals: 1. mandrel; 2.roll; 3. rotation direction of roll; 4. rotation direction of planetary carrier; 5. external layer composite pipe; 6. internal layer base pipe; 7. thread section; 8. reducing section; 9. flattening section; and 10. rounding section.

Embodiment 1

As shown in FIG. 1, the present embodiment provides a manufacturing device and method for a bimetal composite hollow billet, including a frame, a planetary carrier, a plurality of rolls 2 and a mandrel 1, where the planetary carrier is rotatably disposed on the frame; the plurality of rolls 2 are rotatably disposed on the planetary carrier, and the plurality of rolls 2 are disposed around the mandrel 1; a bimetallic pipe to be processed is sleeved on the mandrel 1.
In this specific embodiment, as shown in FIG. 1 to FIG. 2, a roll 2 includes a thread section 7, a flattening section 9, and a rounding section 10 that are sequentially disposed. A reducing section 8 is further disposed between the thread section 7 and the flattening section 9. The roll 2 and the mandrel 1 have a first included angle therebetween. The thread section 7 includes a tapered thread disposed on an outer wall of the roll 2. A larger end of the tapered thread faces the flattening section 9. The mandrel 1 is provided with a guide section protruding outward; the guide section is parallel to the thread section 7, and the guide section is located directly below the thread section 7. A rotation direction of the planetary carrier is opposite to a rotation direction of the plurality of rolls 2.
The manufacturing device and method plastically deform a heated preformed bimetallic sleeve pipe blank through the thread section 7, form a thread groove on the surface of the external composite pipe and a bimetallic interface, cause a secondary plastic deformation under the action of the guide section on the mandrel 1, then flatten and reduce a diameter of the thread groove in the flattening section 9 of the roll 2, and re-round by the rounding section 10.

Embodiment 2

The present embodiment discloses a manufacturing method for a bimetal composite hollow billet, including the following steps:

step 1, heat a preformed bimetallic sleeve pipe blank above a recrystallization temperature;
step 2, sleeve the heated preformed bimetallic sleeve pipe blank on a mandrel 1; and
step 3, start a planetary carrier and a plurality of rolls 2 for rolling.

The preformed bimetallic sleeve pipe blank includes an external layer composite pipe 5 and an internal layer base pipe 6 disposed coaxially; in this embodiment, a wall thickness of the external layer composite pipe 5 is 27% of a wall thickness of the internal layer base pipe 6.
The manufacturing method causes a severe plastic deformation of a bimetallic interface, increases a bonded area between metals on the interface, and promotes the cracking of an oxide layer on the surface of the metals on the interface. Under the action of rolling waste heat, metal atoms on the interface diffuse into each other to form a bimetal composite hollow billet with a firm metallurgical bond, and then hot or cold rolling is performed to produce different specifications of finished bimetal composite pipes with a reinforced metallurgical bond.
While this disclosure includes specific examples, it will be apparent after an understanding of the disclosure of this application that various changes in form and details may be made in these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be considered in a descriptive sense only, and not for purposes of limitation. Descriptions of features or aspects in each example are to be considered as being applicable to similar features or aspects in other examples. Suitable results may be achieved if the described techniques are performed in a different order, and/or if components in a described system, architecture, device, or circuit are combined in a different manner, and/or replaced or supplemented by other components or their equivalents. Therefore, the scope of the disclosure is defined not by the detailed description, but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents are to be construed as being included in the disclosure.

Claims

What is claimed is:

1. A manufacturing device for a bimetal composite hollow billet, comprising:

a mandrel;

a frame;

a planetary carrier rotatably disposed on the frame;

a plurality of rolls rotatably disposed on the planetary carrier, and disposed around the mandrel; and

a bimetallic pipe to be processed is sleeved on the mandrel.

2. The manufacturing device of claim 1, wherein a roll of the plurality of rolls comprises a thread section, a flattening section, and a rounding section that are sequentially disposed.

3. The manufacturing device of claim 2, wherein the roll and the mandrel have a first non-zero angle therebetween.

4. The manufacturing device of claim 2, wherein the thread section comprises a tapered thread disposed on an outer wall of the roll.

5. The manufacturing device of claim 4, wherein a larger end of the tapered thread faces the flattening section.

6. The manufacturing device of claim 4, wherein the mandrel is provided with a guide section protruding outward, the guide section is parallel to the thread section, and the guide section is located directly below the thread section.

7. The manufacturing device of claim 1, wherein a rotation direction of the planetary carrier is opposite to a rotation direction of the plurality of rolls.

8. The manufacturing device of claim 1, wherein the bimetallic pipe is a preformed bimetallic sleeve pipe blank.

9. The manufacturing device of claim 8, wherein the preformed bimetallic sleeve pipe blank is formed by heating the preformed bimetallic sleeve pipe blank above a recrystallization temperature, sleeving the heated preformed bimetallic sleeve pipe blank on the mandrel, and starting the planetary carrier and the plurality of rolls for rolling.

10. The manufacturing device of claim 9, wherein the preformed bimetallic sleeve pipe blank comprises:

an external layer composite pipe and an internal layer base pipe disposed coaxially; and

a wall thickness of the external layer composite pipe is 26%-28.4% of a wall thickness of the internal layer base pipe.

11. A manufacturing method for a bimetal composite hollow billet, comprising:

heating a preformed bimetallic sleeve pipe blank above a recrystallization temperature;

sleeving the heated preformed bimetallic sleeve pipe blank on a mandrel; and

starting a planetary carrier and a plurality of rolls for rolling.

12. The manufacturing method of claim 11, wherein the preformed bimetallic sleeve pipe blank comprises an external layer composite pipe and an internal layer base pipe disposed coaxially; and a wall thickness of the external layer composite pipe is 26%-28.4% of a wall thickness of the internal layer base pipe.

13. The manufacturing method of claim 11, wherein the preformed bimetallic sleeve pipe blank is formed by a manufacturing device, comprising:

the mandrel;

a frame;

a planetary carrier rotatably disposed on the frame;

the plurality of rolls rotatably disposed on the planetary carrier, and disposed around the mandrel; and

the preformed bimetallic sleeve pipe blank to be processed being sleeved on the mandrel.

14. The manufacturing method of claim 13, wherein a roll of the plurality of rolls comprises a thread section, a flattening section, and a rounding section that are sequentially disposed.

15. The manufacturing method of claim 14, wherein the roll and the mandrel have a first non-zero angle therebetween.

16. The manufacturing method of claim 14, wherein the thread section comprises a tapered thread disposed on an outer wall of the roll.

17. The manufacturing method of claim 16, wherein a larger end of the tapered thread faces the flattening section.

18. The manufacturing method of claim 16, wherein the mandrel is provided with a guide section protruding outward, the guide section is parallel to the thread section, and the guide section is located directly below the thread section.

19. The manufacturing method of claim 13, wherein a rotation direction of the planetary carrier is opposite to a rotation direction of the plurality of rolls.