NECKING METHOD, NECKING APPARATUS, AND BATTERY MANUFACTURING DEVICE

1 . A necking method, for forming a necked portion on a shell with an open end, comprising steps of:

forming an annular groove on the shell, wherein the annular groove extends in a circumferential direction of the shell; and

expanding a width of the annular groove towards the open end to form the necked portion.

2 . The necking method according to claim 1 , wherein the step of forming an annular groove on the shell comprises:

limiting the open end when forming the annular groove, so as to limit outward movement of the open end.

3 . The necking method according to claim 2 , wherein the step of expanding a width of the annular groove towards the open end to form the necked portion comprises:

releasing the limit on the open end when expanding the width of the annular groove, so that the open end is folded outward to form a flanged portion.

4 . The necking method according to claim 3 , further comprising:

flattening the flanged portion.

5 . The necking method according to claim 1 , wherein the step of forming an annular groove on the shell comprises:

driving a first roller to rotate around the shell and feed in a radial direction of the shell, so as to form the annular groove on the shell.

6 . The necking method according to claim 5 , wherein the first roller has a first surface and a second surface opposite in its axial direction, and the first surface is farther from the open end than the second surface; and

the step of forming an annular groove on the shell further comprises:

driving the shell to move axially after driving the first roller to rotate around the shell and feed in the radial direction of the shell, so that the shell is deformed, making the first surface attach to a side wall of the annular groove facing the first surface.

7 . The necking method according to claim 5 , wherein the step of expanding a width of the annular groove towards the open end to form the necked portion comprises:

driving a second roller to rotate around the shell and feed in the radial direction of the shell, so as to form the necked portion on the shell, wherein

the second roller has a third surface and a fourth surface opposite in its axial direction, the third surface is farther from the open end than the fourth surface, and a plane where the third surface is located is between two surfaces of the first roller opposite in its axial direction.

8 . A necking apparatus, configured for forming a necked portion on a shell with an open end, comprising:

a first roller, configured to feed in a radial direction of the shell to form an annular groove on the shell; and

a second roller, configured to feed in the radial direction of the shell to form a necked portion and a flanged portion on the shell,

wherein the first roller has a first surface and a second surface opposite in its axial direction, and the second roller has a third surface and a fourth surface opposite in its axial direction,

wherein the third surface is farther from the open end than the fourth surface, and a plane where the third surface is located is between the first surface and the second surface.

9 . The necking apparatus according to claim 8 , wherein a thickness of the first roller is less than that of the second roller.

10 . The necking apparatus according to claim 8 , further comprising:

an inner mold, configured for supporting the shell from interior of the shell, wherein

the first roller and the second roller are disposed on a circumference of the inner mold.

11 . The necking apparatus according to claim 10 , further comprising:

a press fitting member disposed around the inner mold, wherein the press fitting member is configured to:

clamp the open end together with the inner mold when the first roller is fed in the radial direction of the shell, to limit outward movement of the open end.

12 . The necking apparatus according to claim 11 , wherein the press fitting member is movable in an axial direction of the shell, and is configured to:

flatten the outward folded open end on the second roller when the second roller is fed in the radial direction of the shell.

13 . The necking apparatus according to claim 11 , wherein the press fitting member is annular, and the press fitting member is sleeved on the inner mold.

14 . The necking apparatus according to claim 11 , wherein an outer circumferential surface of the inner mold comprises a first outer circumferential surface, a second outer circumferential surface, and a step surface, wherein a diameter of the first outer circumferential surface is greater than that of the second outer circumferential surface, and the step surface connects the first outer circumferential surface and the second outer circumferential surface, wherein the press fitting member is annular, the press fitting member is sleeved on the first outer circumferential surface, the step surface is configured for clamping, together with the press fitting member, the open end, the second outer circumferential surface is configured for mating with the first roller to form the annular groove, and the second outer circumferential surface is configured for mating with the second roller to form the necked portion.

15 . The necking apparatus according to claim 14 , wherein the step surface transitions to the second outer circumferential surface in an arc.

16 . The necking apparatus according to claim 10 , wherein the first roller and the second roller are spaced in a circumferential direction of the inner mold.

17 . The necking apparatus according to claim 8 , further comprising:

a support member, configured for supporting the shell.

18 . The necking apparatus according to claim 17 , further comprising:

a first driving member, configured for driving the support member up and down.

19 . A battery manufacturing device, comprising the necking apparatus according to claim 8 , wherein the necking apparatus is configured for forming the necked portion on a battery shell.