Efficient and reliable steel-lead composite pipe electromagnetic forming method

Abstract

The invention discloses an efficient and reliable steel-lead composite pipe electromagnetic forming method, which relates to the field of electromagnetic forming, and comprises the following steps: a discharge coil, an aluminum pipe, a lead pipe and a steel pipe are coaxially placed in sequence from inside to outside, and a first annular gap is reserved between the steel pipe and the lead pipe; then the steel pipe is fixed through a clamp; and after being fixed, the discharge coil is discharged, so that the aluminum pipe is subjected to diameter expansion deformation, and the lead pipe is driven to be subjected to diameter expansion deformation to be combined with the steel pipe. By the adoption of the scheme, the steel-lead composite pipe higher in bonding strength and reliability is obtained through the large deformation rate of the aluminum pipe under the action of electromagnetic force, and forming is easy and convenient.

Description

Technical Field

[0001] The invention relates to the field of electromagnetic forming, and in particular to an efficient and reliable electromagnetic forming method for a steel-lead composite pipe. Background Art

[0002] In the field of radiation medicine, radiation protection materials are an indispensable component to protect medical staff and patients, and lead alloy materials are commonly used. However, the strength of lead is relatively low and it is difficult to withstand high-intensity loads. To solve this problem, people have proposed a steel / lead layered composite material solution, which meets the requirements of radiation protection of the inner layer and bearing capacity of the outer layer of the radiation protection component, and realizes the combination of the advantages of different metals. Steel-lead composite materials have now become an important radiation protection material and are used in radiation medicine, nuclear power plants and other fields.

[0003] In the prior art, there are many methods for forming steel-lead composite materials, including electromagnetic forming, etc. However, since the material of lead alloy is soft and brittle, it is very easy to break during room temperature plastic forming and is difficult to form. Summary of the invention

[0004] The present invention aims to solve the deficiencies of the prior art and to provide an efficient and reliable electromagnetic forming method for steel-lead composite pipes. By adopting this scheme, a steel-lead composite pipe with higher bonding strength and higher reliability is obtained through the larger deformation rate of the aluminum pipe under the action of electromagnetic force, and the forming is simple and convenient.

[0005] The present invention is achieved through the following technical solutions:

[0006] An efficient and reliable electromagnetic forming method for a steel-lead composite pipe comprises the following steps:

[0007] The discharge coil, the aluminum tube, the lead tube and the steel tube are coaxially placed in sequence from the inside to the outside, and a first annular gap is left between the steel tube and the lead tube;

[0008] The steel pipe is then fixed by a clamp;

[0009] After fixing, the discharge coil is discharged to make the aluminum tube expand and deform, and drive the lead tube to expand and deform and combine with the steel tube.

[0010] Because in the electromagnetic composite method of the prior art, the electrical conductivity of lead and lead alloy is low, and the magnetic permeability is not high, resulting in poor response of the material to the electromagnetic field, and it cannot generate a more obvious current when the coil of the electromagnetic forming equipment is discharged, and the deformation speed is insufficient, and it is difficult to produce a significant bond with the iron pipe; at the same time, due to the soft and brittle characteristics of lead alloy, it is easy to crack when deformed at high speed. In the prior art, the inventor has proposed a method of electromagnetic forming under a high temperature field, which heats the steel pipe to promote the melting and mixing of steel and lead on the interface and the diffusion of elements, to achieve a transitional bonding layer of a certain depth, and at the same time, the temperature gradient residual stress is used to improve the mechanical bonding strength, so as to achieve a reliable bond between steel and lead. However, this method is difficult to operate, and it is necessary to transfer the steel pipe and the lead pipe to the electromagnetic forming equipment after heating, which is easy to burn and difficult to assemble accurately, and the heated lead pipe is easy to burn the outer protective layer of the coil of the electromagnetic forming equipment.

[0011] In order to solve the above problem, the present invention adopts the method of driving the lead pipe with an aluminum pipe. Since aluminum and aluminum alloys have good electrical conductivity, good plasticity and ductility, they have good induction effect under electromagnetic field and will produce a large deformation speed, driving the lead pipe to deform. At the same time, the addition of the lead pipe brings about an electromagnetic shielding effect, and the lead pipe itself will not deform autonomously. It will hit the steel pipe at high speed under the action of the aluminum pipe, so that the two can produce a better bonding effect. The specific scheme includes a discharge coil, an aluminum tube, a lead tube and a steel tube coaxially placed from the inside to the outside, wherein the aluminum tube is made of pure aluminum or aluminum alloy, and the lead tube is made of pure lead or lead alloy. A first annular gap is left between the lead tube and the steel tube to ensure that the lead tube has a certain acceleration distance when expanding and deforming, so as to promote the collision and combination of the lead tube and the steel tube; during the forming process, the discharge coil discharges, and a huge electromagnetic force is generated on the aluminum tube, so that the aluminum or aluminum alloy that is more sensitive to the electromagnetic field produces a larger deformation rate under the action of the electromagnetic force, thereby driving the aluminum tube itself to expand and deform uniformly, and after the aluminum tube is deformed and contacts the lead tube, it will drive the lead tube to expand and deform, so that the lead tube impacts the steel tube at a high speed, and promotes the interface between the two to produce a high-strength metallurgical bond. Compared with the direct electromagnetic forming of the lead tube and the steel tube, the steel-lead composite tube formed by the present invention has a higher bonding strength and higher reliability; compared with the method of heating the steel tube and the lead tube, the forming method of the present invention is simpler and more convenient.

[0012] In order to facilitate the provision of voltage to the discharge coil, an electromagnetic forming device is also included, which includes a capacitor, a charge and discharge circuit and a discharge coil. The capacitor is used to store electrical energy, and the charge and discharge circuit is used to charge the capacitor and discharge the discharge coil.

[0013] As a redundant solution, the steel pipe is made of carbon steel or alloy steel. More specifically, the steel pipe 101 can be carbon steel or alloy steel such as 45 steel, 20 steel, stainless steel, etc.

[0014] In order to make the lead tube deform evenly, a second annular gap is left between the lead tube and the aluminum tube; the width of the second annular gap is 0.5-1 mm. Specifically, during the forming process, it is generally believed that the forming effect is better after the aluminum tube and the lead tube are tightly fitted, but the present invention finds that the forming effect will be better if a certain smaller second annular gap, such as 0.5-1 mm, is left between the lead tube and the aluminum tube. This is because during electromagnetic forming, a certain shaping effect will be produced on the deformation of the aluminum tube. Through the second annular gap, the aluminum tube will become rounder, so that the contact with the aluminum tube will be more uniform, ensuring that the deformation of the lead tube is also more uniform, so that it is not easy to have the phenomenon of uneven local plastic deformation and rupture.

[0015] In order to improve the bonding strength, a transition layer metal is attached to the inner surface of the steel pipe; the transition layer metal is tin or tin alloy. Among them, the tin or tin alloy transition layer can be compounded by plating or tin tube. Tin has good metallurgical bonding with steel and lead materials, so it can improve the interface bonding strength.

[0016] In order to control the impact speed, the width of the first annular gap is 1 to 2 mm; the discharge voltage of the discharge coil is 1 to 9 KV. In this scheme, during the electromagnetic forming process, although the greater the impact speed between the lead pipe and the steel pipe, the stronger the bonding force between the two, in fact, due to the existence of the preheating process, when the discharge voltage is too large, the interface bonding strength will decrease. Therefore, this scheme controls the deformation speed of the lead pipe by controlling the gap width between the steel pipe and the lead pipe to 1 to 2 mm and the discharge voltage to 1 to 9 kV. During the impact process, the material of the lead pipe presents a state similar to that of a fluid, thereby forming a wavy interface morphology at the interface, realizing a mutually interlocking mechanical bonding form at the microscopic level, and greatly improving the interface bonding strength.

[0017] In a further solution, the aluminum tube is made of pure aluminum or aluminum alloy, and the lead tube is made of pure lead or lead alloy.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0019] The present invention provides an electromagnetic forming method for a steel-lead composite pipe that is simple to form at room temperature and has reliable bonding. During the electromagnetic forming process, the aluminum pipe that is more sensitive to the electromagnetic field will produce a larger deformation rate under the action of the electromagnetic force, thereby driving the lead pipe to deform uniformly, prompting the lead pipe to impact the steel pipe at high speed, and producing a high-strength metallurgical bond at the interface between the two. Compared with direct electromagnetic forming of the lead pipe and the steel pipe, the steel-lead composite pipe formed by the embodiment of the present invention has higher bonding strength and higher reliability; compared with the method of heating the steel pipe and the lead pipe, the forming method of the embodiment of the present invention is simpler and more convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0021] Figure 1 A schematic structural diagram of an electromagnetic forming device provided by the present invention;

[0022] Figure 2 A flow chart of the steps of an efficient and reliable electromagnetic forming method for a steel-lead composite pipe provided by the present invention.

[0023] Marks and corresponding parts names in the attached drawings:

[0024] 101- steel pipe, 102- lead pipe, 103- aluminum pipe, 104- discharge coil. DETAILED DESCRIPTION

[0025] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is apparent to one of ordinary skill in the art that these specific details are not necessarily employed to practice the present invention. In other embodiments, in order to avoid obscuring the present invention, well-known structures, circuits, materials, or methods are not specifically described.

[0026] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment," "an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. In addition, it will be appreciated by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0027] In the description of the present invention, the directions or positional relationships indicated by terms such as “front”, “rear”, “left”, “right”, “up”, “down”, “vertical”, “horizontal”, “high”, “low”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the scope of protection of the present invention.

[0028] Embodiment 1:

[0029] Because in the electromagnetic composite method of the prior art, the electrical conductivity of lead and lead alloy is low, and the magnetic permeability is not high, resulting in poor response of the material to the electromagnetic field, and it cannot generate a more obvious current when the coil of the electromagnetic forming equipment is discharged, and the deformation speed is insufficient, and it is difficult to produce a significant bond with the iron pipe; at the same time, due to the soft and brittle characteristics of lead alloy, it is easy to crack when deformed at high speed. In the prior art, the inventor has proposed a method of electromagnetic forming under a high temperature field, which heats the steel pipe to promote the melting and mixing of steel and lead on the interface and the diffusion of elements, to achieve a transitional bonding layer of a certain depth, and at the same time, the temperature gradient residual stress is used to improve the mechanical bonding strength, so as to achieve a reliable bond between steel and lead. However, this method is difficult to operate, and it is necessary to transfer the steel pipe and the lead pipe to the electromagnetic forming equipment after heating, which is easy to burn and difficult to assemble accurately, and the heated lead pipe is easy to burn the outer protective layer of the coil of the electromagnetic forming equipment.

[0030] Therefore, in order to solve the above problems, this embodiment 1 provides an efficient and reliable electromagnetic forming method for steel-lead composite pipes, please refer to Figure 1 and Figure 2 The electromagnetic forming method of the steel-lead composite pipe comprises the following steps:

[0031] S11: The discharge coil 104 , the aluminum tube 103 , the lead tube 102 , and the steel tube 101 are coaxially placed in sequence from the inside to the outside, and a first annular gap exists between the steel tube 101 and the lead tube 102 .

[0032] The steel pipe 101 here can be carbon steel or alloy steel such as 45 steel, 20 steel, stainless steel, etc.

[0033] The electromagnetic forming device includes internal capacitors, charging and discharging circuits, and discharge coils 104. The capacitors are used to store electrical energy, and the charging and discharging circuits are used to charge the capacitors and discharge the discharge coils 104. Figure 2 As shown, the discharge coil 104, the aluminum tube 103, the lead tube 102 and the steel tube 101 are coaxially arranged from the inside to the outside, which is conducive to full utilization of energy. The discharge coil 104 can generate a huge electromagnetic force on the coaxially placed aluminum tube 103, causing it to deform outward, driving the lead tube 102 to collide with the outermost steel tube 101. The first annular gap between the steel tube 101 and the lead tube 102 ensures that the lead tube 102 has a certain acceleration distance, which promotes the collision and combination of the two.

[0034] In the electromagnetic composite method of the prior art, the electrical conductivity of lead and lead alloy is low, and the magnetic permeability is not high, which leads to the poor response of the material to the electromagnetic field, and it cannot generate a more obvious current when the coil of the electromagnetic forming equipment is discharged. The deformation speed is insufficient, and it is difficult to produce a significant combination with the iron pipe; at the same time, due to the soft and brittle characteristics of the lead alloy, it is easy to crack when deformed at a high speed. In addition, in the prior art, the inventor has proposed a method of electromagnetic forming under a high temperature field, which promotes the melting and mixing of steel and lead on the interface and the diffusion of elements, and realizes a transitional bonding layer of a certain depth. At the same time, the temperature gradient residual stress is used to improve the mechanical bonding strength and realize a reliable combination of steel and lead. However, this method is difficult to operate. It is necessary to transfer the steel pipe and the lead pipe to the electromagnetic forming equipment after heating, which is easy to burn and difficult to assemble accurately. Moreover, the heated lead pipe is easy to burn the outer protective layer of the coil of the electromagnetic forming equipment. In this scheme, the aluminum tube 103 is used to drive the lead pipe 102. Aluminum and aluminum alloys have good electrical conductivity and good plastic ductility. They have a good induction effect under the electromagnetic field and will produce a larger deformation speed, driving the lead pipe 102 to deform. At the same time, since the addition of the lead pipe 102 brings about an electromagnetic shielding effect, the lead pipe 102 itself will not deform autonomously, and will collide with the steel pipe 101 at high speed under the action of the aluminum pipe 103, and the two can produce a better fitting effect.

[0035] S12: Fix the clamp to the outside of the steel pipe 101.

[0036] S13: The discharge coil 104 is discharged through the electromagnetic forming equipment to expand the diameter of the lead pipe 102 and deform it to combine with the steel pipe 101.

[0037] In this embodiment, the aluminum tube drives the lead tube 102 and the steel tube 101 to be composited at high speed by the electromagnetic forming method, so that the interface between the steel and the lead is melted and mixed at high speed under the coupling of impact energy and temperature, forming a semi-mechanical and semi-chemical metallurgical bonding form different from other paired metals such as steel and aluminum, forming a transition bonding layer of a certain depth, and ensuring the bonding performance between the steel tube 101 and the lead tube 102. According to the shear test, the interface bonding strength of the composite tube is greater than the strength of the lead tube 102 material itself. This solution avoids the need to heat the lead tube 102 in the prior art, is easy to operate, and prevents high temperature from damaging the discharge coil 104.

[0038] S14: Peeling the aluminum tube 103 off the inner wall of the steel-lead composite tube.

[0039] By stripping the aluminum tube 103 from the inner wall of the composite tube, a steel-lead composite tube is obtained. In some applications, the aluminum tube 103 may not be stripped, which does not affect its electromagnetic shielding effect. At the same time, the aluminum tube 103 also has a good protective effect on the inner side of the lead tube 102, realizing double-sided protection of the lead tube 102.

[0040] The present invention uses the aluminum tube 103 to drive the lead tube 102. Since aluminum and aluminum alloys have good electrical conductivity, good plasticity and ductility, they have good induction effect under the electromagnetic field and produce a large deformation speed, driving the lead tube 102 to deform. At the same time, the addition of the lead tube 102 brings about an electromagnetic shielding effect, and the lead tube 102 itself will not deform autonomously, and will collide with the steel tube 101 at a high speed under the action of the aluminum tube 103, so that the two can produce a better bonding effect. The specific scheme includes a discharge coil 104, an aluminum tube 103, a lead tube 102 and a steel tube 101 which are coaxially arranged from the inside to the outside, wherein the aluminum tube 103 is made of pure aluminum or aluminum alloy, and the lead tube 102 is made of pure lead or lead alloy. A first annular gap is left between the lead tube 102 and the steel tube 101 to ensure that the lead tube 102 has a certain acceleration distance when expanding and deforming, so as to promote the collision and bonding of the lead tube 102 and the steel tube 101. During the forming process, the discharge coil 104 discharges and generates a huge electromagnetic force on the aluminum tube 103, so that the aluminum or aluminum alloy which is more sensitive to the electromagnetic field generates a larger deformation rate under the action of the electromagnetic force, thereby driving the aluminum tube 103 to uniformly expand and deform. After the aluminum tube 103 is deformed and contacts the lead tube 102, it will drive the lead tube 102 to expand and deform, so that the lead tube 102 impacts the steel tube 101 at a high speed, promoting a high-strength metallurgical bonding at the interface between the two. Compared with direct electromagnetic forming of the lead pipe 102 and the steel pipe 101, the steel-lead composite pipe formed by the present invention has higher bonding strength and higher reliability; compared with the method of heating the steel pipe 101 and the lead pipe 102, the forming method of the present invention is simpler and more convenient.

[0041] Embodiment 2:

[0042] This embodiment 2 is further optimized on the basis of embodiment 1, and provides another efficient and reliable electromagnetic forming method for steel-lead composite pipes. Figure 1 and Figure 2 The electromagnetic forming method of the steel-lead composite pipe in this embodiment includes the following steps:

[0043] S21: The discharge coil 104, the aluminum tube 103, the lead tube 102, and the steel tube 101 of the electromagnetic forming equipment are coaxially placed in sequence from the inside to the outside, and a first annular gap exists between the steel tube 101 and the lead tube 102; and a second annular gap exists between the lead tube 102 and the aluminum tube 103;

[0044] In this embodiment, the second annular gap between the lead tube 102 and the aluminum tube 103 is 0.5-1 mm. According to common sense, it is better for the lead tube 102 and the aluminum tube 103 to fit tightly, but the present invention finds that the forming effect is better when a certain smaller gap (0.5-1 mm) is kept between the lead tube 102 and the aluminum tube 103. It is found through research that this is because electromagnetic forming has a certain shaping effect on the aluminum tube 103 after deformation, and the aluminum tube 103 becomes more round, so that the contact between the lead tube and the aluminum tube 103 is more uniform, which ensures that the deformation of the lead tube is also more uniform, and it is not easy to have the phenomenon of uneven local plastic deformation and rupture.

[0045] In this step, in order to improve the bonding strength, a transition layer of metal is attached to the inner surface of the steel tube 101. In this embodiment, a transition layer of tin or tin alloy is used, which can be compounded by plating or tin tube, etc. Tin has good metallurgical bonding with steel and lead materials, so the interface bonding strength can be improved.

[0046] S22: Fix the clamp to the outside of the steel pipe 101.

[0047] S23: The electromagnetic forming equipment is charged and discharged so that the lead pipe 102 is deformed and expanded and combined with the steel pipe 101, and the discharge voltage is 1 to 9 kV.

[0048] According to intuitive experience, during the electromagnetic forming process, the greater the impact speed between the lead pipe 102 and the steel pipe 101, the stronger the bonding force between the two. However, the inventors of the present invention have found that due to the existence of the preheating process, the interface bonding strength is reduced when the discharge voltage is too large. In this embodiment, by controlling the gap width between the steel pipe 101 and the lead pipe 102 to be 1 to 2 mm and the discharge voltage to be 1 to 9 kV, the deformation speed of the lead pipe 102 is controlled. During the impact process, the material of the lead pipe 102 presents a state similar to a fluid, thereby forming a wavy interface morphology at the interface, realizing a mutually interlocking mechanical bonding form at the microscopic level, and greatly improving the interface bonding strength.

[0049] S24: Peeling off the aluminum tube 103 from the inner wall of the steel-lead composite tube.

[0050] The steel-lead composite tube is obtained by peeling the aluminum tube 103 from the inner wall of the composite tube. In some applications, the aluminum tube 103 may not be peeled off, which does not affect its electromagnetic shielding effect.

[0051] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An efficient and reliable electromagnetic forming method for steel-lead composite pipe, characterized in that: The following steps are involved: The discharge coil (104), the aluminum tube (103), the lead tube (102) and the steel tube (101) are coaxially arranged in sequence from the inside to the outside, and a first annular gap is left between the steel tube (101) and the lead tube (102); The steel pipe (101) is then fixed by a clamp; After being fixed, the discharge coil (104) is discharged to expand the diameter of the aluminum tube (103) and deform it, thereby driving the lead tube (102) to expand the diameter and deform it to be combined with the steel tube (101).

2. According to claim 1, an efficient and reliable electromagnetic forming method for steel-lead composite pipes is characterized in that: It also includes an electromagnetic forming device, which includes a capacitor, a charge and discharge circuit and a discharge coil (104). The capacitor is used to store electric energy, and the charge and discharge circuit is used to charge the capacitor and discharge the discharge coil (104).

3. The efficient and reliable electromagnetic forming method of steel-lead composite pipe according to claim 1 is characterized in that: The steel pipe (101) is made of carbon steel or alloy steel.

4. The efficient and reliable electromagnetic forming method of steel-lead composite pipe according to claim 1 is characterized in that: A second annular gap is left between the lead tube (102) and the aluminum tube (103).

5. The efficient and reliable electromagnetic forming method of steel-lead composite pipe according to claim 4 is characterized in that: The width of the second annular gap is 0.5-1 mm.

6. The efficient and reliable electromagnetic forming method of steel-lead composite pipe according to claim 1 is characterized in that: A transition layer of metal is attached to the inner surface of the steel pipe (101).

7. The efficient and reliable electromagnetic forming method of steel-lead composite pipe according to claim 6 is characterized in that: The transition layer metal is tin or tin alloy.

8. The efficient and reliable electromagnetic forming method of steel-lead composite pipe according to claim 1 is characterized in that: The width of the first annular gap is 1 to 2 mm.

9. The efficient and reliable electromagnetic forming method of steel-lead composite pipe according to claim 1 is characterized in that: The discharge voltage of the discharge coil (104) is 1-9KV.

10. An efficient and reliable electromagnetic forming method for a steel-lead composite pipe according to any one of claims 1 to 9, characterized in that: The aluminum tube is made of pure aluminum or aluminum alloy, and the lead tube is made of pure lead or lead alloy.

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