CN218215400U

CN218215400U - Secondary packaging device for soft package battery

Info

Publication number: CN218215400U
Application number: CN202222217000.XU
Authority: CN
Inventors: 李峥; 冯玉川; 覃青波; 李清晖; 王明辉; 何泓材
Original assignee: Yichun Qingtao Energy Technology Co ltd
Current assignee: Yichun Qingtao Energy Technology Co ltd
Priority date: 2022-08-23
Filing date: 2022-08-23
Publication date: 2023-01-03
Anticipated expiration: 2032-08-23

Abstract

The utility model discloses a secondary packaging hardware for laminate polymer battery belongs to laminate polymer battery processing technology field. The secondary packaging device for the soft package battery comprises a supporting mechanism, a packaging mechanism and a preheating mechanism, wherein the supporting mechanism is used for supporting the battery. The packaging mechanism comprises an upper sealing head and a lower sealing head which are oppositely arranged up and down, and the lower sealing head movably penetrates through the supporting mechanism. The packaging mechanism can package the aluminum-plastic film at a first position between the battery cell and the air bag of the battery arranged on the supporting mechanism. The preheating mechanism is located on one side of the packaging mechanism, the preheating mechanism can preheat the aluminum-plastic film at a second position between the battery core of the battery arranged on the supporting mechanism and the air bag, and the second position is located between the first position and the air bag. The utility model discloses be favorable to improving the processingquality of battery.

Description

Secondary packaging device for soft package battery

Technical Field

The utility model relates to a laminate polymer battery processing technology field especially relates to a secondary packaging device for laminate polymer battery.

Background

The soft package battery generally comprises an aluminum-plastic film, a battery cell coated in the aluminum-plastic film and an electrolyte arranged in the aluminum-plastic film. In the process of forming the soft package battery, the battery cell is required to be placed in the pit-filled aluminum-plastic film, and the pit-punched aluminum-plastic film is folded in half to cover the battery cell; then, packaging the top and one side edge of the folded aluminum-plastic film (namely top sealing and side sealing) so as to enable the aluminum-plastic film to be provided with only one side edge opening; injecting electrolyte into the aluminum-plastic film from the opening, pre-sealing (namely, packaging for one time) the opening on the side edge of the left side, standing and forming, and forming an air bag between the opening and the battery cell; in order to prevent water vapor from entering the aluminum-plastic film, the aluminum-plastic film needs to be subjected to heat sealing by a heated sealing head, namely secondary packaging, wherein the secondary packaging is to perform hot-press packaging from one side of the air bag close to the battery cell so that the battery cell is completely sealed in the aluminum-plastic film, a seal is formed between the air bag and the battery cell through heat sealing, and the air bag is cut off.

Because electrolyte is present between the plastic-aluminum membrane, fold the encapsulation back when upper and lower head, electrolyte is heated the vaporization, forms airtight space between seal and electric core main part this moment, and the gas that the vaporization formed is by the seal separation, can produce following problem: 1) A bulge is formed between the two layers of aluminum plastic films, and wrinkles can be generated after the battery is packaged; 2) The generated gas can reduce the vacuum in the battery cell main body, and the battery cell becomes soft; 3) The generated gas affects the cycle life of the cell.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a secondary packaging device for laminate polymer battery reduces the seal after the secondary packaging and the gas between the electric core main part, can improve laminate polymer battery's processingquality.

To achieve the purpose, the utility model adopts the following technical proposal:

a secondary packaging device for a soft package battery comprises a supporting mechanism and a packaging mechanism, wherein the supporting mechanism and the packaging mechanism are used for supporting the battery, the packaging mechanism comprises an upper sealing head and a lower sealing head which are oppositely arranged up and down, and the lower sealing head movably penetrates through the supporting mechanism; the packaging mechanism can set up in first position encapsulation plastic-aluminum membrane between the electric core of the battery on the supporting mechanism and the air pocket, a secondary packaging hardware for laminate polymer battery still includes:

the preheating mechanism is positioned on one side of the packaging mechanism, the preheating mechanism can preheat the aluminum-plastic film at a second position between the battery core and the air bag of the battery, which is arranged on the supporting mechanism, and the second position is positioned between the first position and the air bag.

Optionally, the preheating mechanism comprises:

the upper preheating head is positioned above the supporting mechanism and is connected to an execution end of the first driving piece; and

the lower preheating head is positioned below the upper preheating head, movably penetrates through the supporting mechanism and is connected to an execution end of the second driving piece;

the first driving piece and the second driving piece can drive the upper preheating head and the lower preheating head to be close to or far away from each other.

Optionally, two opposite side surfaces of the upper preheating head and the lower preheating head are respectively provided with an avoidance groove;

when preheating, the plastic-aluminum membrane is located in the avoidance groove.

Optionally, the distance between the first position and the battery cell is d1, the distance between the second position and the battery cell is d2, and d2-d1 is greater than or equal to 0.

Optionally, the distance between the first position and the battery cell is d1, the distance between the second position and the battery cell is d2, wherein d2-d1 is greater than or equal to L, and L is the preheating width of the preheating mechanism.

Optionally, the preheating temperature of the preheating mechanism is T0, wherein T0 is greater than or equal to T1, and T1 is the vaporization temperature of the electrolyte.

Optionally, the support mechanism comprises:

the tray comprises a bottom plate and a baffle arranged on the circumferential direction of the bottom plate in a surrounding mode, and a through hole is formed in the bottom plate to allow the lower end enclosure and the preheating mechanism to penetrate through.

Optionally, the support mechanism further comprises:

the supporting plate is connected to the bottom plate in a sliding mode and is connected to an execution end of the fourth driving piece, the top of the supporting plate is arranged in a positioning groove for positioning the battery, and the fourth driving piece can drive the supporting plate to slide to a preset position.

Optionally, the bayonet device further comprises a bayonet and a third driving member, the bayonet is located above the supporting mechanism, the bayonet is connected to an execution end of the third driving member, and the third driving member can drive the bayonet to lift.

The beneficial effects of the utility model are that:

before carrying out secondary encapsulation to the battery, preheat the plastic-aluminum membrane between plastic-aluminum membrane air pocket and the electric core through preheating the mechanism, can be with the electrolyte vaporization of preheating the department after preheating, the gas of vaporization enters into in the air pocket, thereby make no longer have electrolyte between the two-layer plastic-aluminum membrane of preheating the department, and then encapsulation department no longer has electrolyte vaporization when packaging mechanism encapsulates, thereby can avoid getting into between electric core and the plastic-aluminum membrane after the electrolyte vaporization, be favorable to improving the processingquality of battery.

Drawings

Fig. 1 is a schematic structural diagram of an aluminum-plastic film and a battery cell therein after secondary packaging;

fig. 2 is a perspective view of a secondary packaging device for a soft package battery and a battery according to an embodiment of the present invention;

fig. 3 is a perspective view of a secondary packaging device for a pouch battery according to an embodiment of the present invention;

FIG. 4 is a perspective view of a support mechanism and lower pre-heating head provided in accordance with an embodiment of the present invention;

fig. 5 is a perspective view of an upper preheating head according to an embodiment of the present invention.

In the figure:

100. a battery; 101. an electric core; 102. side sealing; 103. top sealing; 104. a sealing area; 105. a second sealing area; 106. an air bag;

1. a support mechanism; 11. a tray; 111. a base plate; 1111. perforating; 112. a baffle plate; 12. a support plate; 121. positioning a groove; 2. a packaging mechanism; 21. an upper end enclosure; 22. a lower end enclosure; 3. a preheating mechanism; 31. an upper preheating head; 32. a lower preheating head; 33. an avoidance groove; 4. a bayonet.

Detailed Description

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Wherein the terms "first position" and "second position" are two different positions.

Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "secured" are to be construed broadly and encompass, for example, both fixed and removable connections; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

Unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may include the first feature being in direct contact with the second feature, or may include the first feature being in direct contact with the second feature but being in contact with the second feature by another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

The technical solution of the present invention is further explained by the following embodiments with reference to the accompanying drawings.

The secondary packaging process refers to a process of packaging the battery 100 at the edge of the finished battery 100 after the formation process and cutting off the air bag 106 in the subsequent process, and is also called secondary packaging because the battery 100 has been subjected to top-side packaging and primary packaging before the formation.

As shown in fig. 1, the positions of the top seal 103, the side seal 102, the primary package and the secondary package of the battery 100 are packaged, specifically, the top and one side of the aluminum plastic film after folding are packaged (i.e., the top seal 103 and the side seal 102) first, so that only one side of the aluminum plastic film is left open. Injecting electrolyte into the aluminum plastic film from the opening, packaging a sealing area 104 at the opening for one time, and then standing and forming; an air bag 106 is reserved between the sealing area 104 and the battery core 101; finally, the second sealing area 105 on the side of the air bag 106 close to the battery cell 101 is subjected to hot-pressing packaging, i.e. secondary packaging, so that the battery cell 101 is completely sealed in the aluminum plastic film. However, during secondary packaging, the gas formed by vaporization of the electrolyte is present between the cell body and the aluminum-plastic film, which degrades the processing quality of the battery 100.

In order to solve the above problems, the present embodiment provides a secondary packaging device for a pouch battery, which includes a supporting mechanism 1 for supporting a battery 100, a packaging mechanism 2, and a preheating mechanism 3, as shown in fig. 2 to 3. The packaging mechanism 2 comprises an upper sealing head 21 and a lower sealing head 22 which are arranged oppositely up and down, and the lower sealing head 22 movably penetrates through the supporting mechanism 1. The packaging mechanism 2 is capable of packaging an aluminum plastic film at a first position between the battery cell and the air bag of the battery 100 disposed on the support mechanism 1. The preheating mechanism 3 is located at one side of the packaging mechanism 2, the preheating mechanism 3 can preheat the aluminum-plastic film at a second position between the battery core of the battery 100 arranged on the supporting mechanism 1 and the air bag, and the second position is located between the first position and the air bag.

During the use, place battery 100 on supporting mechanism 1, before carrying out secondary packaging to battery 100, preheat the plastic-aluminum membrane between air pocket and the electric core through preheating mechanism 3, can be with the electrolyte vaporization of preheating department after preheating, the gas of vaporization enters into the air pocket, thereby make no longer have electrolyte between the two-layer plastic-aluminum membrane of preheating department, and then encapsulation department no longer has electrolyte vaporization when packaging mechanism 2 encapsulates, thereby can avoid getting into between electric core and the plastic-aluminum membrane after the electrolyte vaporization, be favorable to improving battery 100's processingquality.

In an embodiment of the present application, the preheating temperature of the preheating mechanism 3 is T0, where T0 ≧ T1, and T1 is the vaporization temperature of the electrolyte, and in detail, the preheating temperature is T0 greater than or equal to the vaporization temperature T1 of the electrolyte, so that the electrolyte between two aluminum-plastic films at the preheating position can be vaporized.

As shown in fig. 2 to 5, the preheating mechanism 3 includes an upper preheating head 31, a first driving member (not shown), a lower preheating head 32, and a second driving member (not shown). The upper preheating head 31 is located above the supporting mechanism 1 and connected to the actuating end of the first driving member. The lower preheating head 32 is located below the upper preheating head 31, the lower preheating head 32 movably penetrates through the supporting mechanism 1, and the lower preheating head 32 is connected to an execution end of the second driving member. Wherein the first and second driving members can drive the upper and lower preheating heads 31 and 32 to approach or separate from each other. It can be understood that, when the preheating mechanism 3 performs preheating, the first driving element and the second driving element drive the upper preheating head 31 and the lower preheating head 32 to approach each other, the upper preheating head 31 approaches the upper aluminum-plastic film layer, and the lower preheating head 32 passes through the supporting mechanism 1 to approach the lower aluminum-plastic film layer, so that the electrolyte between the two aluminum-plastic film layers can be vaporized. In detail, heating elements are arranged on the first preheating head and the second preheating head respectively so as to heat the first preheating head and the second preheating head. The specific arrangement of the heating element is conventional and not limited herein. In some alternative embodiments, the first and second drivers are both air cylinders. Of course, the first driving member and the second driving member may be provided in other forms in other embodiments, and are not limited herein.

In particular, in order to prevent the upper and lower aluminum plastic films from being adhered together when the upper and lower preheating heads 31 and 32 preheat the battery 100, two opposite side surfaces of the upper and lower preheating heads 31 and 32 are respectively provided with an avoiding groove 33. During preheating, the aluminum-plastic film is positioned in the avoiding groove 33, so that two layers of aluminum-plastic films are extruded together when the aluminum-plastic film is preheated, and the two layers of aluminum-plastic films are prevented from being bonded together when the aluminum-plastic film is preheated.

In one embodiment of the present application, the preheating temperature T0 of the preheating mechanism 3 is less than the melting temperature of the PP layer inside the aluminum plastic film, so that the upper preheating head 31 and the lower preheating head 32 do not adhere to the upper aluminum plastic film and the lower aluminum plastic film when they approach the battery.

In an embodiment of the application, a distance between the first position and the battery cell is d1, and a distance between the second position and the battery cell is d2, where d2-d1 is greater than or equal to 0.

In an embodiment of the application, a distance between the first position and the battery cell is d1, and a distance between the second position and the battery cell is d2, where d2-d1 is greater than or equal to L, and L is a preheating width of the preheating mechanism 3.

In some embodiments of the present application, the widths of the upper preheating head 31 and the lower preheating head 32 are greater than or equal to the widths of the upper sealing head 21 and the lower sealing head 22, the widths of the upper preheating head 31 and the lower preheating head 32 are the same, and the widths of the upper sealing head 21 and the lower sealing head 22 are the same.

As shown in fig. 3-4, the supporting mechanism 1 includes a tray 11, the tray 11 includes a bottom plate 111 and a baffle 112 surrounding the bottom plate 111, and the bottom plate 111 is provided with a through hole 1111 for the lower head 22 and the preheating mechanism 3 to pass through. Through the arrangement of the baffle plate 112, the electrolyte can only flow on the bottom plate 111, and the electrolyte is prevented from flowing into other positions to enlarge the pollution range.

In some embodiments of the present disclosure, a cavity (not shown) is further disposed in the tray 11, and a vacuum hole communicating with the cavity is formed at the top of the tray 11. The cavity is communicated with an external vacuumizing device. In detail, the cavity is communicated with a vacuum extractor through a pipeline.

As an implementation mode of the application, the top of the tray 11 is provided with a groove, the cover plate is arranged at the opening of the groove in a covering mode, and the groove and the cover plate form a cavity body, so that the processing of the cavity body can be facilitated. In detail, the vacuum hole is provided on the cover plate, so that communication of the vacuum hole and the cavity can be facilitated.

Furthermore, at least one side wall of the groove is obliquely arranged, at least one end of the vacuum hole is positioned above the obliquely arranged side wall of the groove, so that electrolyte flowing into the vacuum hole can flow into the cavity conveniently, and the electrolyte is prevented from flowing out along the bottom surface of the cover plate.

In one embodiment of the present application, the vacuum holes are provided in plurality, the vacuum holes are kidney-shaped holes, and the vacuum holes are arranged at intervals in a direction perpendicular to an extending direction of the vacuum holes. When the external vacuum-pumping device starts to operate, the gas in the supporting mechanism 1 is taken out of the supporting structure through the vacuum holes; thus, the airflow in the upper portion of the tray 11 passes through the vacuum holes to form a directional, top-down, directional airflow. The electrolyte flowing out of the air bags of the batteries on the tray 11 can only move on the tray under the flow guiding effect of the directionally flowing air flow without splashing, so that the batteries and the inside of the supporting mechanism can be prevented from being polluted, and the processing quality of the batteries can be guaranteed.

In one embodiment of the present application, in order to prevent the electrolyte in the battery from being carried out by the air flow as much as possible, the height of the tray 11 on the side close to the preheating mechanism 3 is larger than the height of the tray on the side away from the preheating mechanism 3.

As a preferred embodiment of the present application, the tray forms an angle of 5 ° to 10 ° with the horizontal plane. In the process of vacuumizing, gas on the upper part of the tray enters the vacuum holes from top to bottom; the gas in the lower part of the tray enters the vacuum holes from the side. Therefore, in the entire support mechanism, neither the electrolyte in the battery nor the electrolyte carried out by the gas is subjected to upward gas force.

As an embodiment of the present application, the tray of the present application is horizontally placed.

In an embodiment of the present application, the thickness of the side of the battery 100 provided with the battery core 101 is thicker, the thickness of the side forming the air bag 106 is thinner, if the side of the air bag 106 is suspended, the air bag is not easy to puncture the air bag 106, in order to enable the electrolyte brought out by the gas to smoothly flow out, the top of the tray is provided with a step shape, and the vacuum hole is arranged on the higher side of the tray, so as to support the air bag.

In order to facilitate loading and unloading of the battery 100, as shown in fig. 2-4, the supporting mechanism 1 further includes a supporting plate 12 and a fourth driving member (not shown), the supporting plate 12 is slidably connected to the bottom plate 111 and is connected to an executing end of the fourth driving member, the top of the supporting plate 12 is disposed in a positioning groove 121 for positioning the battery 100, and the fourth driving member can drive the supporting plate 12 to slide to a preset position. In detail, when needing to carry out the material loading to battery 100, constant head tank 121 top on the layer board 12 does not shelter from, can be convenient for put into constant head tank 121 with battery 100 in, after putting battery 100, slide to preset the position through fourth drive piece drive layer board 12, at this moment, packaging mechanism 2 is just right with the first position, preheat mechanism 3 and second position just right, so that preheat and secondary package, after battery 100 secondary package is accomplished, reset through fourth drive piece drive layer board 12, take off battery 100, so that next battery 100's material loading.

In order to puncture the air bag, as shown in fig. 2 to 3, the secondary packaging device for the pouch battery in this embodiment further includes a lancet 4 and a third driving member (not shown), the lancet 4 is located above the supporting mechanism 1, the lancet 4 is connected to an execution end of the third driving member through a connecting member, and the third driving member can drive the lancet 4 to move up and down. It will be understood that when the air bag needs to be punctured, the driver drives the bayonet 4 downward, so that the air bag of the battery 100 placed on the support mechanism 1 can be punctured. In detail, the bayonet 4 is located on the side of the preheating mechanism 3 away from the packaging mechanism 2, so that the bayonet 4 is opposite to the air bag. The bayonet 4 is preferably provided in plurality, and each bayonet 4 is connected to the connector, so that the electrolyte and the gas generated by formation in the air bag 106 can be discharged quickly, and the secondary packaging efficiency can be improved. Optionally, the third driver is a cylinder.

A clearance groove is formed in the position, corresponding to the bayonet 4, of the tray 11, and in the process of puncturing the air bag 106, the bayonet 4 moves downwards under the action of the third driving piece, and the bayonet 4 extends into the clearance groove to puncture the air bag 106.

As an embodiment, the clearance groove is a blind hole; it does not extend through the tray 11 but merely provides a receiving area for the bayonet 4.

In one embodiment, the number m of the vacuum holes is larger than or equal to the number n of the bayonet knives and the positions of at least (m-l) vacuum holes correspond to the bayonet knives 4, wherein l is the number of the clearance grooves.

It will be understood that positional correspondence means that the lancet 4 can extend into the vacuum hole during the process of puncturing the air pocket 106.

When the secondary packaging device for the soft package battery in the embodiment is used, when an external vacuum device starts to operate, a closed cavity is formed in the supporting mechanism 1, the third driving piece is used for driving the bayonet 4 to descend to puncture the air bag, airflow in the secondary packaging device can be enabled to flow directionally through the vacuum hole, electrolyte brought out by the gas can flow to the vacuum hole through the tray 11 under the diversion effect of the airflow flowing directionally, so that the electrolyte can be prevented from splashing to pollute the inside of the battery and the secondary packaging device, the quality of the battery is further ensured, and finally, the fifth driving piece and the sixth driving piece respectively drive the upper end socket 21 and the lower end socket 31 to be close to each other to carry out heat sealing on the battery 100.

In detail, the upper head 21 is connected to an actuating end of a fifth driving member (not shown), and the lower head 22 is connected to an actuating end of a sixth driving member (not shown). In detail, the upper head 21 and the lower head 22 are respectively connected with a heating element, the upper head 21 and the lower head 22 can be heated, and the upper head 21 and the lower head 22 are driven by the fifth driving member and the sixth driving member to heat-seal the battery 100. In some alternative embodiments, the fifth driver and the sixth driver are both pneumatic cylinders. Of course, the fifth driving element and the sixth driving element may be provided in other forms in other embodiments, and are not limited herein.

The technical principle of the present invention is described above with reference to specific embodiments. The description is made for the purpose of illustrating the principles of the invention and is not to be construed in any way as limiting the scope of the invention. Based on the explanations herein, those skilled in the art will be able to conceive of other embodiments of the present invention without any inventive effort, which would fall within the scope of the present invention.

Claims

1. A secondary packaging device for a soft package battery comprises a supporting mechanism (1) and a packaging mechanism (2) which are used for supporting a battery (100), wherein the packaging mechanism (2) comprises an upper sealing head (21) and a lower sealing head (22) which are oppositely arranged up and down, and the lower sealing head (22) movably penetrates through the supporting mechanism (1); the packaging mechanism (2) can package an aluminum-plastic film at a first position between an electric core of the battery (100) arranged on the supporting mechanism (1) and the air bag, and is characterized in that the secondary packaging device for the soft package battery further comprises:

the preheating mechanism (3) is located on one side of the packaging mechanism (2), the preheating mechanism (3) can preheat the aluminum-plastic film at a second position between the battery core and the air bag of the battery (100) arranged on the supporting mechanism (1), and the second position is located between the first position and the air bag.

2. The secondary packaging device for pouch batteries according to claim 1, characterized in that said preheating mechanism (3) comprises:

the upper preheating head (31) is positioned above the supporting mechanism (1) and is connected with an execution end of the first driving piece; and

the lower preheating head (32) is positioned below the upper preheating head (31), the lower preheating head (32) movably penetrates through the supporting mechanism (1), and the lower preheating head (32) is connected to an execution end of the second driving piece;

wherein the first driving member and the second driving member can drive the upper preheating head (31) and the lower preheating head (32) to approach or separate from each other.

3. The secondary packaging device for the soft package battery according to claim 2, wherein two opposite side surfaces of the upper preheating head (31) and the lower preheating head (32) are provided with avoidance grooves (33);

when preheating, the aluminum-plastic film is positioned in the avoiding groove (33).

4. The secondary packaging device for the soft package battery is characterized in that the first position is at a distance d1 from the battery core, the second position is at a distance d2 from the battery core, wherein d2-d1 is greater than or equal to L, and L is the preheating width of the preheating mechanism (3).

5. The secondary packaging device for the soft package battery is characterized in that the preheating temperature of the preheating mechanism (3) is T0, wherein T0 is more than or equal to T1, and T1 is the vaporization temperature of the electrolyte.

6. The secondary packaging device for pouch batteries according to any of claims 1 to 5, characterized by the fact that said supporting means (1) comprise:

the tray (11), tray (11) include bottom plate (111) and enclose and establish baffle (112) of bottom plate (111) circumference, bottom plate (111) are last to have seted up perforation (1111) so that lower head (22) and preheating mechanism (3) pass.

7. The secondary packaging device for pouch batteries according to claim 6, characterized by that the support mechanism (1) further comprises:

the battery pack comprises a supporting plate (12) and a fourth driving piece, wherein the supporting plate (12) is connected to the bottom plate (111) in a sliding mode and is connected to an execution end of the fourth driving piece, the top of the supporting plate (12) is arranged in a positioning groove (121) for positioning the battery (100), and the fourth driving piece can drive the supporting plate (12) to slide to a preset position.

8. The secondary packaging device for the soft package battery is characterized by further comprising a bayonet (4) and a third driving member, wherein the bayonet (4) is located above the supporting mechanism (1), the bayonet (4) is connected to an execution end of the third driving member, and the third driving member can drive the bayonet (4) to ascend and descend.