A fuse and its overcurrent protection and reset method

Abstract

The present invention proposes a fuse and an overcurrent protection and reset method thereof, wherein the fuse comprises a shell, a first melt and a second melt, wherein the first melt and the second melt are respectively inserted into the shell from both sides of the first direction of the shell; the shell is provided with a sealed cavity pre-filled with a protective gas, and the shell can extend or contract along the first direction; in a first state, the first melt and the second melt are in abutment connection; in a second state, the first melt and the second melt are disconnected; the protective gas expands due to heat, and the shell extends along the first direction, switching from the first state to the second state; the protective gas contracts after cooling, and the shell contracts along the first direction, restoring the first state. There is no need to replace the first melt and the second melt, and the fuse can be used repeatedly. The disconnection and conduction of the circuit are achieved by the thermal expansion and contraction of the protective gas and the shell, without the need to add other devices. The structure is simple and compact, and it occupies little space.

Description

Technical Field

[0001] The present invention relates to the technical field of battery pack circuit protection devices, and in particular to a fuse and an overcurrent protection and reset method thereof. Background Art

[0002] In order to handle emergency situations when a circuit malfunctions or anomalies occur, existing battery packs usually have fuses installed in the circuit. A fuse is an electrical device that uses the heat generated by itself to melt the fuse element when the current exceeds a specified value, thereby disconnecting the circuit. When a circuit malfunctions or anomalies occur, as the current continues to rise, the fuse installed in the circuit can disconnect the circuit and play a role in protecting the circuit. Existing fuses are generally disposable. When a circuit malfunctions or anomalies occur, the fuse element will melt. To restore circuit conductivity, the fuse needs to be replaced, which is time-consuming, labor-intensive, and costly.

[0003] To address the above problems, a Chinese invention patent with publication number CN109524279B in the prior art discloses an energy-saving fuse. The magnitude of the current is proportional to the magnitude of the magnetic field. Therefore, when an overload problem occurs in the circuit, the magnetic force will also increase accordingly. The magnetic attraction is used to overcome the spring force. With the cooperation of the linkage structure, the circuit is automatically disconnected. After disconnection, the linkage mechanism is reset under the spring force to make the circuit conductive, and the circuit can be reused. However, this solution requires not only an electromagnet and a coil, but also a spring, which makes the structure complex and occupies a large space. Summary of the Invention

[0004] In view of this, the present invention proposes a fuse, which can extend or shrink along the first direction through the shell, so that the first fuse and the second fuse move away from each other to achieve disconnection or move closer to each other to achieve resistance connection, thereby realizing the disconnection and conduction of the circuit. The first fuse and the second fuse do not need to be replaced, and the fuse can be used repeatedly. It has a simple and compact structure and occupies little space.

[0005] The technical solution of the present invention is achieved as follows:

[0006] In a first aspect, the present invention provides a fuse for a battery pack, characterized in that it includes a housing, a first fuse and a second fuse, wherein:

[0007] The first melt and the second melt are respectively inserted into the shell from both sides of the shell in a first direction;

[0008] The housing is provided with a sealed cavity pre-filled with a protective gas, and the housing can be extended or contracted along a first direction;

[0009] In a first state, the first melt and the second melt are in contact and connected;

[0010] In the second state, the first melt and the second melt are disconnected;

[0011] The protective gas expands due to heat, and the shell extends in a first direction, switching from the first state to the second state;

[0012] The protective gas contracts after cooling, and the shell contracts along the first direction to restore the first state.

[0013] On the basis of the above technical solution, preferably, a telescopic portion is provided on the side surface of the shell along the first direction, and the outer surface of the telescopic portion is wavy.

[0014] On the basis of the above technical solution, preferably, it also includes a supporting skeleton, which is arranged in the sealing cavity, and the supporting skeleton includes a skeleton body, and the skeleton body is provided with a first guide part and a second guide part, the first melt is overlapped with the first guide part, and the second melt is overlapped with the second guide part.

[0015] On the basis of the above technical solution, preferably, the support skeleton further includes positioning columns, the positioning columns are protruding from the skeleton body, and the positioning columns are respectively connected to the first melt and the second melt.

[0016] On the basis of the above technical solution, preferably, the positioning column includes a first cylinder and a second cylinder, the first cylinder is located between the second cylinder and the skeleton body, and the diameter of the first cylinder is larger than the diameter of the second cylinder; a first waist-shaped hole is provided at one end of the first melt close to the second melt, the length direction of the first waist-shaped hole is parallel to the first direction of the shell, and the first cylinder passes through the first waist-shaped hole; a second waist-shaped hole is provided at one end of the second melt close to the first melt, the length direction of the second waist-shaped hole is parallel to the first direction of the shell, and the second cylinder passes through the second waist-shaped hole.

[0017] On the basis of the above technical solution, preferably, the longitudinal section of the skeleton body is hexagonal, and the first guide portion and the second guide portion are two symmetrical surfaces of the skeleton body.

[0018] On the basis of the above technical solution, preferably, the first melt is provided with a first bending portion, and the position where the first bending portion overlaps with the first guide portion is adapted to the shape of the first guide portion; the second melt is provided with a second bending portion, and the position where the second bending portion overlaps with the second guide portion is adapted to the shape of the second guide portion.

[0019] On the basis of the above technical solution, preferably, a connecting piece is provided on the second melt, and the connecting piece and the first melt are separated from each other to achieve disconnection or are close to each other to achieve contact connection.

[0020] On the basis of the above technical solution, preferably, the shell is provided with a first mounting hole and a second mounting hole, one end of the first melt is inserted into the sealed cavity through the first mounting hole, and the gap between the first melt and the first mounting hole is sealed by glue; one end of the second melt is inserted into the sealed cavity through the second mounting hole, and the gap between the second melt and the second mounting hole is sealed by glue.

[0021] On the basis of the above technical solution, preferably, it also includes a positive contact knife and a negative contact knife, the positive contact knife and the negative contact knife are respectively located on both sides of the first direction of the shell, the positive contact knife is connected to the other end of the first melt, and the negative contact knife is connected to the other end of the second melt.

[0022] In a second aspect, the present invention provides a method for overcurrent protection and resetting a fuse, comprising:

[0023] Step S101: the current passing through the first melt and the second melt exceeds a preset threshold, and the first melt and the second melt generate a large amount of heat;

[0024] Step S102: The protective gas in the sealed cavity expands due to heat, pushing the shell to extend in a first direction, and the first melt and the second melt are disconnected;

[0025] Step S103: the protective gas contracts after cooling, the shell contracts along the first direction, and the first melt and the second melt are in contact and connected.

[0026] The fuse of the present invention has the following beneficial effects compared with the prior art:

[0027] (1) By setting a sealed cavity filled with a protective gas, in the second state, the current passing through the first melt and the second melt exceeds a preset threshold value, and the large amount of heat generated causes the protective gas to expand due to the heat, and the shell extends along the first direction, driving the first melt and the second melt away from each other to achieve disconnection, so that the circuit is disconnected. After the circuit is disconnected, no current passes through the first melt and the second melt, and no heat is generated. The protective gas gradually cools and shrinks, and the shell shrinks along the first direction, driving the first melt and the second melt to approach each other to achieve a contact connection, so that the circuit is conductive. The first melt and the second melt do not need to be replaced, and the fuse can be used repeatedly. The disconnection and conduction of the circuit are achieved by the thermal expansion and contraction of the protective gas and the shell, without the need to add other devices. The structure is simple and compact, and takes up little space.

[0028] (2) The shell is provided with a telescopic portion on the side surface along the first direction to achieve directional extension or contraction of the shell, thereby achieving disconnection or collision between the first melt and the second melt;

[0029] (3) By arranging the first melt to overlap the first guide portion and the second melt to overlap the second guide portion, the movement of the first melt and the second melt is guided to ensure that the first melt and the second melt can achieve contact or disconnection during the movement, thereby improving the stability of the device;

[0030] (4) By setting a positioning column including a first cylinder and a second cylinder, the first cylinder passes through the first waist-shaped hole, and the second cylinder passes through the second waist-shaped hole, the movement direction and amplitude of the first melt and the second melt are limited, and the movement amplitude is accurately controlled to avoid the movement distance being too large to be restored, ensuring that the first melt and the second melt can achieve collision or disconnection during the movement process, thereby improving the stability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 is a perspective view of a fuse according to the present invention;

[0033] Figure 2 is a cross-sectional view of the fuse of the present invention;

[0034] Figure 3 A perspective view of the housing and support frame of the present invention (housing cross-section);

[0035] Figure 4 is a perspective view of a first melt of the present invention;

[0036] Figure 5 is a perspective view of a second melt of the present invention;

[0037] Figure 6 It is a flow chart of the working method of the fuse of the present invention.

[0038] The figure marks in the above drawings are: 100-sealed cavity; 1-shell, 11-telescopic part, 12-first mounting hole, 13-second mounting hole; 2-first melt, 21-first waist-shaped hole, 22-first bending part; 3-second melt, 31-second waist-shaped hole, 32-second bending part, 33-connecting piece; 4-support frame, 41-skeleton body, 411-first guide part, 412-second guide part, 42-positioning column, 421-first cylinder, 422-second cylinder; 5-positive contact knife; 6-negative contact knife. DETAILED DESCRIPTION

[0039] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] Reference Figure 1-Figure 5 As shown, an embodiment of the present invention provides a fuse for a battery pack, comprising a housing 1, a first fuse 2, and a second fuse 3, wherein:

[0041] The first melt 2 and the second melt 3 are respectively inserted into the shell 1 and are respectively located on both sides of the shell 1 in a first direction;

[0042] The interior of the housing 1 is a hollow sealed cavity 100 filled with a protective gas. The housing 1 can extend or contract along a first direction.

[0043] In the first state, the first fuse 2 and the second fuse 3 are in contact with each other; the first state is that the circuit of the battery pack is in a normal working state;

[0044] In the second state, the current passing through the first fuse 2 and the second fuse 3 exceeds a preset threshold value, and the large amount of heat generated causes the protective gas to expand due to the heat, and the shell 1 extends in the first direction, so that the first fuse 2 and the second fuse 3 are separated from each other to achieve contact disconnection. The second state refers to a circuit failure or abnormality of the battery pack, accompanied by a continuous increase in current. The preset threshold value can be set according to the current used in the actual circuit;

[0045] The protective gas contracts after cooling, and the shell 1 contracts along the first direction. The first melt 2 and the second melt 3 approach each other to achieve abutting connection, and the first state is restored.

[0046] In this embodiment, the first direction can be the length direction or the width direction, the shell 1 is made of rubber, the protective gas is generally helium or nitrogen, and the protective gas is filled in the sealed cavity 100. The first melt 2 and the second melt 3 are generally made of pure metal or alloy conductive materials. In this solution, aluminum or copper is preferably used, which has better thermal conductivity. When a large current passes through the first melt 2 and the second melt 3, the heat generated causes the protective gas to expand due to the heat, and the shell 1 extends along the first direction, driving the first melt 2 and the second melt 3 away from each other to achieve contact breaking, so that the circuit is disconnected. After the circuit is disconnected, no current passes through the first melt 2 and the second melt 3, and no heat is generated. The protective gas gradually cools and shrinks, and the shell 1 shrinks along the first direction, driving the first melt 2 and the second melt 3 to move closer to each other to achieve a contact connection, so that the circuit is conductive.

[0047] The fuse proposed in the embodiment of the present invention can extend or contract along the first direction through the shell 1, so that the first fuse 2 and the second fuse 3 move away from each other to achieve disconnection or move closer to each other to achieve resistance connection, thereby realizing the disconnection and conduction of the circuit. The first fuse 2 and the second fuse 3 do not need to be replaced, and the fuse can be used repeatedly. The disconnection and conduction of the circuit are achieved by the thermal expansion and contraction of the protective gas and the shell 1, without the need to add other devices. The structure is simple and compact, and takes up little space.

[0048] The fuse proposed in this embodiment can be used not only in battery packs, but also in other devices that require circuit protection.

[0049] In one embodiment, Figure 3 As shown, the housing 1 is provided with a telescopic portion 11 on the side surface along the first direction, and the outer surface of the telescopic portion 11 is wavy. The telescopic portions 11 are symmetrically provided on two side surfaces of the housing 1 along the first direction. By providing the telescopic portions 11, the telescopic portions 11 can expand and extend when heated and return to their original length when cooled, thereby achieving directional extension or contraction of the housing 1 and achieving contact or collision between the first melt 2 and the second melt 3.

[0050] In one embodiment, Figure 3As shown, the fuse also includes a support skeleton 4, which is arranged in the sealed cavity 100. The support skeleton 4 includes a skeleton body 41, and the skeleton body 41 is provided with a first guide portion 411 and a second guide portion 412. The first melt 2 is overlapped on the first guide portion 411, and the second melt 3 is overlapped on the second guide portion 412. The skeleton body 41 is made of PP (polypropylene) or PE (polyethylene) and can be injection molded. By arranging the first melt 2 to overlap on the first guide portion 411 and the second melt 3 to overlap on the second guide portion 412, the movement of the first melt 2 and the second melt 3 is guided, ensuring that the first melt 2 and the second melt 3 can achieve interference or disconnection during the movement, thereby improving the stability of the device.

[0051] In one embodiment, Figure 3 As shown, the support frame 4 further includes positioning posts 42, which protrude from the frame body 41 and are connected to the first melt 2 and the second melt 3. By providing the positioning posts 42, the movement directions of the first melt 2 and the second melt 3 are limited, ensuring that the first melt 2 and the second melt 3 can achieve contact or disconnection during movement, thereby improving the stability of the device.

[0052] In a specific embodiment, Figure 3 As shown, the positioning column 42 includes a first cylinder 421 and a second cylinder 422, the first cylinder 421 is located between the second cylinder 422 and the skeleton body 41, and the diameter of the first cylinder 421 is larger than the diameter of the second cylinder 422; the first melt 2 is provided with a first waist-shaped hole 21 at one end close to the second melt 3, the length direction of the first waist-shaped hole 21 is parallel to the first direction of the shell 1, and the first cylinder 421 passes through the first waist-shaped hole 21; the second melt 3 is provided with a second waist-shaped hole 31 at one end close to the first melt 2, the length direction of the second waist-shaped hole 31 is parallel to the first direction of the shell 1, and the second cylinder 422 passes through the second waist-shaped hole 31. By passing the first cylinder 421 through the first waist-shaped hole 21 and the second cylinder 422 through the second waist-shaped hole 31, the movement direction and amplitude of the first melt 2 and the second melt 3 are limited, and the movement amplitude is accurately controlled to avoid the movement distance being too large and unable to recover, ensuring that the first melt 2 and the second melt 3 can achieve conflict or disconnection during the movement process, thereby improving the stability of the device.

[0053] In one embodiment, Figure 3As shown, the longitudinal cross-section of the skeleton body 41 is hexagonal, and the first guide portion 411 and the second guide portion 412 are two symmetrical surfaces of the skeleton body 41. By setting the longitudinal cross-section of the skeleton body 41 to be hexagonal, the top and bottom surfaces are respectively parallel to the telescopic portion 11, and the two adjacent surfaces of the top surface serve as the first guide portion 411 and the second guide portion 412, respectively, and the two adjacent surfaces of the bottom surface serve as the first guide portion 411 and the second guide portion 412, respectively, to guide the two groups of first melts 2 and the two groups of second melts 3, respectively, and provide support for the first melts 2 and the second melts 3, thereby preventing the first melts 2 and the second melts 3 from bending and collapsing after heating.

[0054] In one embodiment, Figure 4 and Figure 5 As shown, the first melt 2 is provided with a first bend 22, and the location where the first bend 22 overlaps the first guide 411 is adapted to the shape of the first guide 411; the second melt 3 is provided with a second bend 32, and the location where the second bend 32 overlaps the second guide 412 is adapted to the shape of the second guide 412. The provision of the first bend 22 and the second bend 32 can increase the tensile strength of the first melt 2 and the second melt 3, and can achieve a rigid connection effect during stretching and contraction.

[0055] In one embodiment, Figure 5 As shown, a connecting piece 33 is provided on the second melt 3. The connecting piece 33 and the first melt 2 move away from each other to achieve disconnection or move closer to each other to achieve a contact connection. When the telescopic portion 11 is extended, the connecting piece 33 and the second melt 3 move away from each other to achieve disconnection, disconnecting the circuit. No current flows through the first melt 2 and the second melt 3, and thus no heat is generated. This prevents the first melt 1 and the second melt 2 from melting and deforming significantly, ensuring that the first melt 2 and the second melt 3 can recover. When the telescopic portion 11 contracts, the connecting piece 33 and the second melt 3 move closer to each other to achieve a contact connection, completing the circuit.

[0056] In one embodiment, Figure 3As shown, the housing 1 is provided with a first mounting hole 12 and a second mounting hole 13. One end of the first melt 2 is inserted into the sealed cavity 100 through the first mounting hole 12, and the gap between the first melt 2 and the first mounting hole 12 is sealed by applying glue. One end of the second melt 3 is inserted into the sealed cavity 100 through the second mounting hole 13, and the gap between the second melt 3 and the second mounting hole 13 is sealed by applying glue. By inserting one end of the first melt 2 into the sealed cavity 100 through the first mounting hole 12 and one end of the second melt 3 into the sealed cavity 100 through the second mounting hole 13, the first melt 2 and the second melt 3 can be easily connected to conductive components outside the sealed cavity 100, and the gap is sealed by applying glue, ensuring the sealing of the sealed cavity 100.

[0057] In one embodiment, Figure 1 and Figure 2 As shown, the fuse further includes a positive contact blade 5 and a negative contact blade 6, which are respectively located on either side of the housing 1 in the first direction. The positive contact blade 5 is connected to the other end of the first fuse 2, and the negative contact blade 6 is connected to the other end of the second fuse 3. By connecting the positive contact blade 5 to the other end of the first fuse 2 and the negative contact blade 6 to the other end of the second fuse 3, it is convenient to connect the fuse to the wire, facilitate the removal and installation of the fuse, and improve the convenience of the device.

[0058] The working principle of the fuse is as follows: after a circuit failure or abnormality occurs, a large current will pass through the first melt 2 and the second melt 3. The heat generated will cause the protective gas to expand due to the heat, and the telescopic part 11 will extend, driving the first melt 2 and the second melt 3 to move away from each other to achieve contact breaking, thereby disconnecting the circuit; after the circuit is disconnected, no current will pass through the first melt 2 and the second melt 3, and no heat will be generated. The protective gas will gradually cool down and shrink, and the telescopic part 11 will shrink, driving the first melt 2 and the second melt 3 to move closer to each other to achieve a contact connection, thereby connecting the circuit. The fuse does not need to be replaced after it is blown, and will automatically recover after the temperature returns to normal temperature, thereby saving costs and improving efficiency.

[0059] Based on the same inventive concept, the embodiment of the present invention proposes an overcurrent protection and reset method for the fuse as described above, such as Figure 6 Shown, including:

[0060] Step S101: the current passing through the first melt 2 and the second melt 3 exceeds a preset threshold, and the first melt 2 and the second melt 3 generate a large amount of heat;

[0061] Step S102: The protective gas in the sealed cavity 100 expands due to heat, pushing the shell 1 to extend in a first direction, and the first melt 2 and the second melt 3 break contact;

[0062] Step S103 : the protective gas contracts after cooling, the shell 1 contracts along the first direction, and the first melt 2 and the second melt 3 are in contact and connected.

[0063] The working method of the fuse proposed in an embodiment of the present invention is that the current passing through the first melt 2 and the second melt 3 exceeds a preset threshold value, and the large amount of heat generated causes the protective gas to expand due to the heat, and the shell 1 extends along the first direction and enters the second state. In the second state, the first melt 2 and the second melt 3 are disconnected, and the circuit is disconnected; the first melt 2 and the second melt 3 no longer generate heat, and the protective gas contracts after cooling, and the shell 1 contracts along the first direction to restore the first state, and the circuit is connected. The first melt 2 and the second melt 3 do not need to be replaced, and the fuse can be used repeatedly. The disconnection and conduction of the circuit are achieved by the thermal expansion and contraction of the protective gas and the shell 1, without the need to add other devices. The structure is simple and compact, and it takes up little space.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit 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. A fuse for a battery pack, characterized in that: It comprises a shell (1), a first melt (2), a second melt (3) and a support frame (4), wherein: The housing (1) is provided with a telescopic portion (11) on a side surface along a first direction, and the outer surface of the telescopic portion (11) is wavy; The first melt (2) and the second melt (3) are respectively inserted into the shell (1) from both sides of the shell (1) in a first direction; The housing (1) is provided with a sealed cavity (100) pre-filled with a protective gas, and the housing (1) is capable of extending or contracting along a first direction; In a first state, the first melt (2) and the second melt (3) are in contact connection; In the second state, the first melt (2) and the second melt (3) are disconnected; The protective gas expands due to heat, and the shell (1) stretches in a first direction, switching from a first state to a second state; The protective gas contracts after cooling, and the shell (1) contracts along the first direction to restore the first state; The support frame (4) is arranged in the sealed cavity (100), the support frame (4) comprises a frame body (41), the frame body (41) is provided with a first guide portion (411) and a second guide portion (412), the first melt (2) is overlapped on the first guide portion (411), and the second melt (3) is overlapped on the second guide portion (412); The longitudinal section of the skeleton body (41) is hexagonal, and the first guide portion (411) and the second guide portion (412) are two symmetrical surfaces of the skeleton body (41); the first melt (2) is provided with a first bending portion (22), and the position where the first bending portion (22) overlaps with the first guide portion (411) is adapted to the shape of the first guide portion (411); the second melt (3) is provided with a second bending portion (32), and the position where the second bending portion (32) overlaps with the second guide portion (412) is adapted to the shape of the second guide portion (412).

2. The fuse according to claim 1, wherein The support frame (4) further comprises positioning columns (42), the positioning columns (42) being arranged to protrude from the frame body (41), and the positioning columns (42) being connected to the first melt (2) and the second melt (3) respectively.

3. The fuse according to claim 2, wherein: The positioning column (42) includes a first cylinder (421) and a second cylinder (422), the first cylinder (421) is located between the second cylinder (422) and the skeleton body (41), and the diameter of the first cylinder (421) is larger than the diameter of the second cylinder (422); a first waist-shaped hole (21) is provided at one end of the first melt (2) close to the second melt (3), the length direction of the first waist-shaped hole (21) is parallel to the first direction of the shell (1), and the first cylinder (421) passes through the first waist-shaped hole (21); a second waist-shaped hole (31) is provided at one end of the second melt (3) close to the first melt (2), the length direction of the second waist-shaped hole (31) is parallel to the first direction of the shell (1), and the second cylinder (422) passes through the second waist-shaped hole (31).

4. The fuse according to any one of claims 1 to 3, characterized in that: A connecting piece (33) is provided on the second melt (3), and the connecting piece (33) and the first melt (2) are spaced apart from each other to achieve disconnection or are brought close to each other to achieve contact connection.

5. The fuse according to claim 4, wherein: The shell (1) is provided with a first mounting hole (12) and a second mounting hole (13); one end of the first melt (2) is inserted into the sealed cavity (100) through the first mounting hole (12), and the gap between the first melt (2) and the first mounting hole (12) is sealed by applying glue; one end of the second melt (3) is inserted into the sealed cavity (100) through the second mounting hole (13), and the gap between the second melt (3) and the second mounting hole (13) is sealed by applying glue.

6. The fuse according to claim 5, wherein: It also includes a positive electrode contact knife (5) and a negative electrode contact knife (6), wherein the positive electrode contact knife (5) and the negative electrode contact knife (6) are respectively located on both sides of the first direction of the shell (1), the positive electrode contact knife (5) is connected to one end of the first melt (2), and the negative electrode contact knife (6) is connected to one end of the second melt (3).

7. A method for overcurrent protection and resetting a fuse according to any one of claims 1 to 6, characterized in that: include: Step S101: the current passing through the first melt (2) and the second melt (3) exceeds a preset threshold, and the first melt (2) and the second melt (3) generate a large amount of heat; Step S102: The protective gas in the sealed cavity (100) expands due to heat, pushing the shell (1) to extend in a first direction, and the first melt (2) and the second melt (3) are disconnected; Step S103: the protective gas contracts after cooling, the shell (1) contracts along the first direction, and the first melt (2) and the second melt (3) are in contact and connected.

Images