Copper pipe production equipment

Abstract

The utility model provides copper pipe production equipment. The copper pipe production equipment provided by the utility model comprises a heat preserving furnace, a mold and a crystallizer, a copper liquid outlet is formed in the side wall of the heat preservation furnace, the mold is connected to the side of the heat preservation furnace, the mold is provided with a forming cavity, the forming cavity is communicated with the copper liquid outlet, and the crystallizer is arranged on the outer side of the mold and surrounds the circumferential outer wall of the mold; the crystallizer comprises an inner shell and an outer shell, the inner shell abuts against the outer wall of the mold, the inner shell is sleeved with the outer shell, the inner shell and the outer shell define a water flow channel, and the water flow channel spirally extends in the length direction of the mold around the axial direction of the mold, so that the heating uniformity of the crystallizer is guaranteed, the cooling effect is improved, and deformation caused by uneven heating of the crystallizer is avoided; the service life of the crystallizer is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of metal casting, in particular to a copper pipe production device. Background Art

[0002] Copper rods and copper tubes have high strength and good wear resistance. They can be used for copper sleeves, sealing rings, screws, nuts and other parts with high strength requirements. Copper parts have high durability and reliability.

[0003] In the related art, copper tubes are usually formed by casting. Copper tube production equipment melts raw materials to form molten copper. The molten copper passes through a holding furnace. A crystallizer is set at the outlet of the holding furnace. The molten copper is cooled by the crystallizer so that the molten copper is crystallized to form a copper tube. After the copper tube is pulled out, a billet is produced, which can be used to produce copper parts.

[0004] However, the current crystallizer is easily deformed due to uneven heating, resulting in a shorter crystallizer life. Utility Model Content

[0005] The embodiment of the utility model provides a copper tube production equipment to solve the technical problem that the crystallizer in the current copper tube production equipment is easily subjected to uneven heating, causing the crystallizer to deform, resulting in a shorter crystallizer life.

[0006] The present application provides a copper tube production device, which includes a heat preservation furnace, a mold and a crystallizer. The side wall of the heat preservation furnace is provided with a copper liquid outlet, the mold is connected to the side of the heat preservation furnace, and the mold has a molding cavity, which is connected to the copper liquid outlet.

[0007] Among them, the crystallizer is arranged on the outside of the mold and around the circumferential outer wall of the mold; the crystallizer includes an inner shell and an outer shell, the inner shell abuts against the outer wall of the mold, the outer shell is sleeved on the outside of the inner shell, the inner shell and the outer shell are arranged to form a water flow channel, and the water flow channel spirally extends around the axial direction of the mold along the length direction of the mold.

[0008] The copper tube production equipment provided in the embodiment itself sets a cooling water flow channel with a spiral structure inside the crystallizer, so that cooling water enters from one end of the crystallizer and flows out from the other end. In the process of the cooling water flowing through the water flow channel, the cooling water absorbs heat from different positions around the mold, thereby ensuring the uniformity of heating of the crystallizer, improving the cooling effect, avoiding deformation of the crystallizer due to uneven heating, and increasing the service life of the crystallizer.

[0009] As an optional embodiment, the water flow channel has a water inlet and a water outlet, the water inlet is located at one end of the crystallizer close to the holding furnace, and the water outlet is located at one end of the crystallizer away from the holding furnace.

[0010] With this arrangement, cooling water can flow from the higher temperature end to the lower temperature end, improving the cooling effect.

[0011] As an optional implementation, the water inlet and the water outlet are both arranged on the side wall of the shell.

[0012] Such an arrangement can improve the convenience of the docking installation of the cooling water pipeline.

[0013] As an optional embodiment, the crystallizer may further include a water inlet pipe and a water outlet pipe, wherein the water inlet pipe is connected to the water inlet, and the water outlet pipe is connected to the water outlet; the water inlet pipe and the water outlet pipe are both arranged on the upper side of the crystallizer.

[0014] With such an arrangement, the weight of the cooling water can be utilized to improve the flow efficiency of the cooling water.

[0015] As an optional embodiment, a protrusion structure is provided on the outer wall of the inner shell, and the top of the protrusion structure abuts against the inner wall of the outer shell; the protrusion structure spirally extends along the longitudinal direction of the mold around the axial direction of the mold to form a water flow channel.

[0016] With such an arrangement, the cooling water flow can be guided by the protruding structure, thereby improving the smoothness of the cooling water flow.

[0017] As an optional implementation, the pitches of the protruding structures along the axial direction of the mold remain equal.

[0018] Such an arrangement can improve the uniformity of cooling of the crystallizer and avoid local overheating.

[0019] As an optional implementation, the cross-sectional widths of the protruding structure at different positions along its extension direction remain equal.

[0020] This setting can keep the cooling water flow rate stable and keep the return water temperature of the crystallizer within the preset temperature.

[0021] As an optional implementation, connecting flanges are provided at both ends of the crystallizer along the extension direction of the mold, and sealing parts are provided between the outer shell and the inner shell at the positions of the connecting flanges.

[0022] This arrangement can avoid cooling water leakage.

[0023] As an optional embodiment, the copper tube production equipment may further include an electromagnetic stirring device, which is located at one end of the mold facing the insulation furnace; the crystallizer is located on the side of the electromagnetic stirring device away from the insulation furnace; there is a spacing between the electromagnetic stirring device and the crystallizer along the axial direction of the mold, and the size of the spacing is greater than or equal to 20 mm and less than or equal to 80 mm.

[0024] This arrangement can increase the equiaxed crystal rate at the center of the copper tube and improve the uniformity of the crystal phase of the copper tube.

[0025] As an optional implementation, the outer shell and the inner shell are both made of copper.

[0026] Such an arrangement can improve the high temperature resistance of the crystallizer and increase the service life of the crystallizer.

[0027] The present application provides a copper tube production device, which includes a heat preservation furnace, a mold and a crystallizer. The side wall of the heat preservation furnace is provided with a copper liquid outlet, the mold is connected to the side of the heat preservation furnace, the mold has a molding cavity, the molding cavity is connected to the copper liquid outlet, the crystallizer is arranged on the outside of the mold, and is arranged around the circumferential outer wall of the mold; the crystallizer includes an inner shell and an outer shell, the inner shell abuts against the outer wall of the mold, the outer shell is sleeved on the outside of the inner shell, the inner shell and the outer shell are surrounded to form a water flow channel, the water flow channel surrounds the axial direction of the mold and spirally extends along the length direction of the mold, thereby ensuring the uniformity of heating of the crystallizer, improving the cooling effect, avoiding deformation of the crystallizer due to uneven heating, and improving the service life of the crystallizer.

[0028] In addition to the technical problems solved by the embodiments of the present application described above, the technical features that constitute the technical solutions, and the beneficial effects brought about by the technical features of these technical solutions, other technical problems that can be solved by the copper tube production equipment provided by the present application, other technical features included in the technical solutions, and the beneficial effects brought about by these technical features will be further described in detail in the specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 A schematic diagram of the structure of a copper tube production device provided in an embodiment of the present application;

[0031] Figure 2 A schematic diagram of the structure of the mold forming position in the copper tube production equipment provided in the embodiment of the present application;

[0032] Figure 3 A partial view of the position of the crystallizer in the copper tube production equipment provided in an embodiment of the present application.

[0033] Description of reference numerals:

[0034] 100-heat-keeping furnace; 101-copper liquid outlet;

[0035] 200-mold; 201-molding cavity;

[0036] 300-Electromagnetic stirring device;

[0037] 400 - crystallizer; 401 - water flow channel; 402 - water inlet; 403 - water outlet; 410 - inner shell; 420 - outer shell; 430 - water inlet pipe; 440 - water outlet pipe; 450 - raised structure. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0039] First, those skilled in the art should understand that these implementations are only used to explain the technical principles of the present application and are not intended to limit the scope of protection of the present application. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0040] Secondly, it should be noted that in the description of the present application, terms such as "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present application.

[0041] In addition, it should be noted that in the description of this application, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0042] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0043] The accuracy of the mixing ingredients of additives in the copper foil production industry directly affects the quality of copper foil. Additive technology can effectively improve the tensile strength, ductility and other properties of copper foil. At present, copper tubes are usually formed by casting. The copper tube production equipment melts the raw materials to form copper liquid. The copper liquid passes through the insulation furnace. A crystallizer is set at the outlet of the insulation furnace. The copper liquid is cooled by the crystallizer so that the copper liquid crystallizes and forms a copper tube. After the copper tube is pulled out, a blank is produced, which can be used to produce copper parts.

[0044] However, the current crystallizer is easily deformed due to uneven heating, resulting in a shorter crystallizer life.

[0045] An embodiment of the present application provides a copper tube production equipment, which provides a cooling water flow channel with a spiral structure inside the crystallizer so that cooling water enters from one end of the crystallizer and flows out from the other end. In the process of the cooling water flowing through the water flow channel, the cooling water absorbs heat from different positions around the mold, thereby ensuring the uniformity of heating of the crystallizer, improving the cooling effect, avoiding deformation of the crystallizer due to uneven heating, and increasing the service life of the crystallizer.

[0046] To facilitate understanding, the application scenario of the copper tube production equipment provided in the embodiment of the present application is first described.

[0047] The copper tube produced by the copper tube production equipment provided in the embodiment of the present application can be a red copper tube, or a brass tube, a red copper tube, an aluminum bronze tube, a phosphor bronze tube, or other types of copper tubes, and the embodiment of the present application does not specifically limit this. The copper tube produced by the copper tube production equipment provided in the embodiment of the present application can be used in different scenarios such as air conditioning condensation pipelines, water heater pipelines, and heating pipelines, and the embodiment of the present application does not specifically limit this.

[0048] Figure 1 This is a schematic diagram of the structure of the copper tube production equipment provided in the embodiment of the present application. Figure 2 This is a schematic diagram of the structure of the mold forming position in the copper tube production equipment provided in the embodiment of the present application. Figure 3 A partial view of the position of the crystallizer in the copper tube production equipment provided in an embodiment of the present application.

[0049] like Figures 1 to 3 , as shown, the copper tube production equipment provided by the embodiment of the present application includes a holding furnace 100, a mold 200 and a crystallizer 400. The raw materials required for production can enter the holding furnace 100 after being smelted into molten copper. The holding furnace 100 is used to control the temperature of the molten copper and continuously provide the molten copper required for continuous casting of the copper tube to the mold 200.

[0050] The side wall of the holding furnace 100 is provided with a copper liquid outlet 101, and the mold 200 is connected to the side of the holding furnace 100. The mold 200 has a molding cavity 201, and the molding cavity 201 is connected to the copper liquid outlet 101. The mold 200 is used to provide a molding cavity 201 for the copper liquid to solidify and form a copper tube. The crystallizer 400 is arranged on the outside of the mold 200 and is arranged around the circumferential outer wall of the mold 200. The crystallizer 400 can cool the copper liquid in the mold 200 so that the copper liquid solidifies and forms a copper tube.

[0051] In some embodiments, the crystallizer 400 includes an inner shell 410 and an outer shell 420. The inner shell 410 abuts against the outer wall of the mold 200, and the outer shell 420 is sleeved on the outside of the inner shell 410. The inner shell 410 and the outer shell 420 are arranged to form a water flow channel 401. The water flow channel 401 surrounds the axial direction of the mold 200 and extends spirally along the length direction of the mold 200.

[0052] It is understandable that when the copper tube production equipment starts to cast the copper tube ingot, the crystallizer 400 can be started in advance and cooling water can be introduced into the water flow channel 401. During the copper tube casting process, the copper liquid in the molding cavity 201 of the mold 200 transfers heat to the crystallizer 400 through the mold 200, and the crystallizer 400 takes away the heat through the cooling water, thereby achieving crystallization and solidification of the copper liquid.

[0053] It should be noted that in the copper tube production equipment provided in the embodiment of the present application, a cooling water flow channel 401 with a spiral structure is arranged inside the crystallizer 400, so that cooling water enters from one end of the crystallizer 400 and flows out from the other end. In the process of the cooling water flowing through the water flow channel 401, the cooling water absorbs heat from different positions around the mold 200, thereby ensuring the uniformity of heating of the crystallizer 400, improving the cooling effect, avoiding deformation of the crystallizer 400 due to uneven heating, and increasing the service life of the crystallizer 400.

[0054] The specific water inlet and outlet method and the formation structure of the water flow channel 401 are described in detail below.

[0055] Please continue to refer to Figures 1 to 3 In one possible implementation, the water flow channel 401 has a water inlet 402 and a water outlet 403. The water inlet 402 is located at one end of the crystallizer 400 close to the insulation furnace 100, and the water outlet 403 is located at the end of the crystallizer 400 away from the insulation furnace 100, so that cooling water can flow from the higher temperature end to the lower temperature end, thereby improving the cooling effect.

[0056] It is understandable that temperature sensors may be provided at both the water inlet 402 and the water outlet 403, and the temperature sensors may be used to monitor the water inlet temperature of the water inlet 402 and the return water temperature of the water outlet 403. In addition, a water pump may be used to provide power for the flow of cooling water.

[0057] In addition, the cooling water can be circulated. The cooling water flowing out from the water outlet 403 can enter the water flow channel 401 again through the water inlet 402 after being cooled externally, thereby achieving a circulating cooling effect in the crystallizer 400.

[0058] In some embodiments, the water inlet 402 and the water outlet 403 are both disposed on the side wall of the housing 420 , thereby improving the convenience of the docking installation of the cooling water pipeline.

[0059] Exemplarily, the water inlet 402 may be disposed on the water inlet pipe 430, which may be integrally formed with the housing 420. The water outlet 403 may be disposed on the water outlet pipe 440, which may be integrally formed with the housing 420. The water inlet pipe 430 and the water outlet pipe 440 may be connected to an external water supply pipeline and a water return pipeline, respectively.

[0060] It should be noted that the water inlet pipe 430 is connected to the water inlet 402, the water outlet pipe 440 is connected to the water outlet 403, and the water inlet pipe 430 and the water outlet pipe 440 are both arranged on the upper side of the crystallizer 400, so that the weight of the cooling water can be used to improve the flow efficiency of the cooling water.

[0061] In one possible implementation, a protrusion structure 450 is provided on the outer wall of the inner shell 410, and the top of the protrusion structure 450 abuts against the inner wall of the outer shell 420. The protrusion structure 450 spirally extends along the length direction of the mold 200 around the axial direction of the mold 200 to form a water flow channel 401, so that the cooling water can be guided to flow through the protrusion structure 450 to improve the smoothness of the cooling water flow.

[0062] It is understandable that the protrusion structure 450 can be integrally formed with the inner shell 410 , thereby reducing the manufacturing cost of the crystallizer 400 .

[0063] Exemplarily, the pitch of the protruding structure 450 along the axial direction of the mold 200 remains equal, thereby improving the uniformity of cooling of the crystallizer 400 and avoiding local overheating.

[0064] Exemplarily, the cross-sectional widths of the protruding structure 450 at different positions along its extension direction remain equal, so that the cooling water flow rate can be kept stable and the return water temperature of the crystallizer 400 can be maintained within a preset temperature.

[0065] In some embodiments, the crystallizer 400 is provided with connecting flanges at both ends along the extension direction of the mold 200, and sealing parts are provided between the outer shell 420 and the inner shell 410 at the positions of the connecting flanges to prevent cooling water leakage.

[0066] Exemplarily, the return water temperature of the cooling water in the water flow channel 401 of the crystallizer 400 can be controlled within the range of 46±2°C.

[0067] It should be noted that cooling water is introduced into the spiral water flow channel 401 to allow the copper liquid to crystallize and solidify, and the return water temperature is controlled within a reasonable range, which can refine the grains during copper tube casting and improve the structural defects that may occur during casting.

[0068] Please continue to refer to Figures 1 to 3 In a possible implementation, the copper tube production equipment may further include an electromagnetic stirring device 300, which is located at one end of the mold 200 facing the insulation furnace 100, and the electromagnetic stirring device 300 can stir the copper liquid in the mold 200. The crystallizer 400 is located on the side of the electromagnetic stirring device 300 away from the insulation furnace 100.

[0069] The electromagnetic stirring device 300 is sleeved on the outer side of the mold 200 in the circumferential direction, and the electromagnetic stirring device 300 is located at one end of the mold 200 facing the holding furnace 100. The electromagnetic stirring device 300 is configured to generate a magnetic field in the molding cavity 201. Since the copper liquid in the mold 200 is metal, the magnetic field acts on the copper liquid to drive the copper liquid to rotate and flow.

[0070] It can be understood that the principle of the electromagnetic stirring device 300 driving the copper liquid in the mold 200 to stir is: the electromagnetic stirring device 300 acts as a stator on the outside of the mold 200, and the copper liquid in the mold 200 is equivalent to a rotor. When current is passed through the electromagnetic stirring device 300, a magnetic field can be generated. The magnetic field passes through the mold 200 and acts on the copper liquid in the molding cavity 201, so that the copper liquid in the mold 200 generates an induced potential and current, and the induced current generated by the copper liquid can interact with the magnetic field generated by the electromagnetic stirring device 300 to generate an electromagnetic force, and the electromagnetic force drives the copper liquid to flow in a directional manner, thereby achieving the effect of stirring the copper liquid.

[0071] In addition, the mold 200 has a certain length, and the molding cavity 201 of the mold 200 can have a liquid area and a fixed area along its length direction. There is a transition zone between the liquid area and the fixed area. The transition zone has a solid-liquid interface. The copper liquid flows from the liquid area to the solid area. The electromagnetic stirring device 300 is opposite to the liquid area, and the crystallizer 400 covers the solid area.

[0072] It should be noted that in the copper tube production equipment provided in the embodiment of the present application, an electromagnetic stirring device 300 is arranged on the outside of the mold 200 to stir the copper liquid entering the mold 200 from the copper liquid outlet 101, thereby ensuring the uniformity of the wall thickness of the cast copper tube, and refining the grains during copper tube casting, improving the pores, center cracks, slag inclusions, delamination and other structural defects that may occur during casting, thereby increasing the equiaxed crystal rate in the center of the copper tube and improving the uniformity of the crystal phase of the copper tube.

[0073] In some embodiments, there is a spacing between the electromagnetic stirring device 300 and the crystallizer 400 along the axial direction of the mold 200, and the size of the spacing is greater than or equal to 20 mm and less than or equal to 80 mm, thereby ensuring that the temperature of the molten copper flowing in the mold 200 changes gradually, which can increase the equiaxed crystal rate in the center of the copper tube and improve the uniformity of the crystal phase of the copper tube.

[0074] For example, the specific value of the axial spacing dimension between the electromagnetic stirring device 300 and the crystallizer 400 along the mold 200 can be 20 mm, 21 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 79 mm, 80 mm, etc., and the embodiments of the present application do not make specific limitations on this.

[0075] It should be noted that the outer shell 420 and the inner shell 410 can both be made of copper, thereby improving the high temperature resistance of the crystallizer 400 and increasing the service life of the crystallizer 400.

[0076] An embodiment of the present application provides a copper tube production device, which includes a heat preservation furnace 100, a mold 200 and a crystallizer 400. A copper liquid outlet 101 is provided on the side wall of the insulation furnace 100, and the mold 200 is connected to the side of the insulation furnace 100. The mold 200 has a molding cavity 201, which is communicated with the copper liquid outlet 101. The crystallizer 400 is arranged on the outside of the mold 200 and is arranged around the circumferential outer wall of the mold 200; the crystallizer 400 includes an inner shell 410 and an outer shell 420, the inner shell 410 abuts against the outer wall of the mold 200, and the outer shell 420 is sleeved on the outside of the inner shell 410. The inner shell 410 and the outer shell 420 are surrounded to form a water flow channel 401, and the water flow channel 401 surrounds the axial direction of the mold 200 and extends spirally along the length direction of the mold 200, thereby ensuring the uniformity of heating of the crystallizer 400, improving the cooling effect, avoiding deformation of the crystallizer 400 due to uneven heating, and improving the service life of the crystallizer 400.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.

Claims

1. A copper tube production equipment, characterized in that: It comprises a holding furnace, a mold and a crystallizer; the side wall of the holding furnace is provided with a copper liquid outlet, the mold is connected to the side of the holding furnace, the mold has a molding cavity, and the molding cavity is connected to the copper liquid outlet; The crystallizer is arranged on the outside of the mold and around the circumferential outer wall of the mold; the crystallizer includes an inner shell and an outer shell, the inner shell abuts against the outer wall of the mold, the outer shell is sleeved on the outside of the inner shell, the inner shell and the outer shell are arranged to form a water flow channel, and the water flow channel spirally extends around the axial direction of the mold along the length direction of the mold.

2. The copper tube production equipment according to claim 1, characterized in that: The water flow channel has a water inlet and a water outlet. The water inlet is located at one end of the crystallizer close to the insulation furnace, and the water outlet is located at one end of the crystallizer away from the insulation furnace.

3. The copper tube production equipment according to claim 2, characterized in that: The water inlet and the water outlet are both arranged on the side wall of the shell.

4. The copper tube production equipment according to claim 2, characterized in that: The crystallizer further comprises a water inlet pipe and a water outlet pipe, wherein the water inlet pipe is connected to the water inlet, and the water outlet pipe is connected to the water outlet; the water inlet pipe and the water outlet pipe are both arranged on the upper side of the crystallizer.

5. The copper tube production equipment according to any one of claims 1 to 4, characterized in that: A protruding structure is provided on the outer wall of the inner shell, and the top of the protruding structure abuts against the inner wall of the outer shell; the protruding structure spirally extends along the longitudinal direction of the mold around the axial direction of the mold to form the water flow channel.

6. The copper tube production equipment according to claim 5, characterized in that: The pitches of the protruding structures along the axial direction of the mold are kept equal.

7. The copper tube production equipment according to claim 5, characterized in that: The cross-sectional widths of the protruding structure at different positions along its extending direction remain equal.

8. The copper tube production equipment according to any one of claims 1 to 4, characterized in that: The two ends of the crystallizer along the extension direction of the mold are provided with connecting flanges, and sealing parts are provided between the outer shell and the inner shell at the positions of the connecting flanges.

9. The copper tube production equipment according to any one of claims 1 to 4, characterized in that: It also includes an electromagnetic stirring device, which is located at one end of the mold facing the insulation furnace; the crystallizer is located on the side of the electromagnetic stirring device away from the insulation furnace; there is a spacing between the electromagnetic stirring device and the crystallizer along the axial direction of the mold, and the size of the spacing is greater than or equal to 20 mm and less than or equal to 80 mm.

10. The copper tube production equipment according to any one of claims 1 to 4, characterized in that: The outer shell and the inner shell are both made of copper.

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