CN108724780B

CN108724780B - Battery sealing element forming method

Info

Publication number: CN108724780B
Application number: CN201810502257.5A
Authority: CN
Inventors: 张智建; 葛辉明; 刘金成
Original assignee: Eve Energy Co Ltd
Current assignee: Eve Energy Co Ltd
Priority date: 2018-05-23
Filing date: 2018-05-23
Publication date: 2021-09-24
Anticipated expiration: 2038-05-23
Also published as: CN108724780A

Abstract

The invention discloses a battery sealing element forming method, which comprises the following steps: s100, carrying out extrusion forming, namely forming the master batch into a platy thin film plate in an extrusion mode; step S200, performing, namely stamping the film plate into a first blank by adopting a pre-stamping die, wherein the first blank is of a cylindrical structure with one open end and one sealed end, and an extending edge extends outwards from the open end of the first blank; step S300, trimming, removing the extending edge and part of the sealing end and forming a second blank; and S400, performing punch forming, and inwards folding the residual sealing end of the second blank by adopting a punching die to form a sealing element. The sealing element with extremely thin thickness can be produced by adopting the combination of extrusion forming, preforming, trimming and stamping forming, the utilization rate of materials is improved, and the manufacturing cost of the sealing element is greatly reduced.

Description

Battery sealing element forming method

Technical Field

The invention relates to the technical field of battery manufacturing, in particular to a battery sealing piece forming method of an ultrathin button battery.

Background

In the field of button batteries, a battery sealing element is an important component of the battery, and the battery sealing element is related to the sealability of the battery and directly influences the service life of the battery. With the increasing energy density requirement of button cells, the thickness of the sealing element is designed to be thinner and thinner. Especially for miniature button lithium ion batteries, the thinning of the sealing element has greater significance for improving the energy density. In order to ensure the sealing performance of the battery, the material of the sealing member needs to have the characteristics of acid resistance, alkali resistance, high temperature resistance, high strength and the like, and the material usually selected is thermoplastic plastics with high melting point such as PFA (fusible polytetrafluoroethylene), polyamide, polyether ether ketone and the like. Because of the special material of the sealing element, the sealing element is difficult to form, and the sealing element is formed by adopting an injection molding method at present, and the forming method has the following defects: 1. a special injection mold needs to be developed, and the mold opening cost is high; 2. the material is easily seriously wasted in the injection molding process, and the material utilization rate is low; 3. poor temperature compensation for materials with too high melting points tends to result in poor flow properties and inability to injection mold thin seals.

Disclosure of Invention

The invention aims to: the battery sealing element forming method is convenient to operate and form, low in cost and high in material utilization rate.

In order to achieve the purpose, the embodiment of the invention adopts the following technical scheme:

provided is a battery sealing member forming method, comprising the following steps:

s100, carrying out extrusion forming, namely forming the master batch into a platy thin film plate in an extrusion mode;

step S200, performing, namely stamping the film plate into a first blank piece by adopting a pre-stamping die, wherein the first blank piece is of a cylindrical structure with an opening at one end and a sealed end, and an extending edge extends towards the outer side from the opening end of the first blank piece;

step S300, trimming, removing the extending edge and part of the sealing end, and forming a second blank;

and S400, performing punch forming, and inwards folding the residual sealing end of the second blank part by adopting a stamping die to form a sealing element.

Preferably, the extending edge and a part of the sealing end are removed by stamping.

Preferably, a trimming mold is used for removing the extending edge and a part of the sealing end, the trimming mold comprises an upper trimming mold and a lower trimming mold, the upper trimming mold comprises a first body, a first accommodating groove is concavely arranged on one side of the first body, a first convex part for punching a part of the sealing end is convexly arranged at the center of the bottom of the first accommodating groove, the lower trimming mold comprises a second body matched with the first accommodating groove, a second accommodating groove is concavely arranged on the second body, the first convex part can be inserted into the second accommodating groove, and a shearing step for removing the extending edge is annularly arranged on the outer periphery of the second body.

Preferably, the film plate is thinned during the preforming, so that the thickness of the first blank after the preforming is consistent with the thickness of the sealing member.

Preferably, the second blank member is thinned during the press forming to form the sealing member.

Preferably, the upper stamping die and the lower stamping die of the stamping die are heated before the upper stamping die and the lower stamping die are combined, and the upper stamping die and the lower stamping die jointly extrude each position of the second blank to realize the thinning treatment in the process of combining the upper stamping die and the lower stamping die.

Preferably, the step S400 includes the steps of:

step S410, sleeving the second blank piece outside the lower stamping die, and enabling the remaining sealing end to protrude out of the upper end of the lower stamping die;

step S420, heating the lower stamping die and the upper stamping die simultaneously;

and S430, slowly pressing the upper stamping die until the upper stamping die and the lower stamping die are matched to form the sealing element.

Preferably, the thickness of the extruded film plate member is made to be equal to the thickness of the sealing member in the extrusion molding.

Preferably, the preforming temperature during preforming is 300-350 ℃, the pressing speed of preforming is 5-10 mm/min, and the preforming pressure is 0.3-0.7 MPa.

Preferably, the stamping temperature of an upper stamping die of the stamping die during stamping forming is 100-200 ℃, the pressing speed of the upper stamping die is 5-10 mm/min, and the pressing force of the upper stamping die is 0.3-0.7 MPa.

The embodiment of the invention has the beneficial effects that: the sealing element with extremely thin thickness can be produced by adopting the combination of extrusion forming, preforming, trimming and stamping forming, the utilization rate of materials is improved, and the manufacturing cost of the sealing element is greatly reduced. Compared with the prior art, the method completely cancels the step of injection molding, does not need to design a high-cost injection mold, simultaneously avoids material waste in the injection molding process, improves the utilization rate of materials, can realize the extremely thin thickness of the film plate in an extrusion molding mode, further ensures that the wall thickness of the molded sealing element can be extremely thin, and improves the energy density of the button cell.

Drawings

The invention is explained in more detail below with reference to the figures and examples.

Fig. 1 is a schematic structural diagram of an extruded thin film plate according to an embodiment of the present invention.

FIG. 2 is a schematic structural diagram of a preformed first blank member according to an embodiment of the present invention.

Fig. 3 is a schematic view of a state in which the upper trimming mold and the lower trimming mold of the trimming mold according to the embodiment of the present invention are closed.

Fig. 4 is a schematic view of a state in which the upper and lower punching dies of the punching die according to the embodiment of the present invention are closed.

FIG. 5 is a schematic cross-sectional view of a seal according to an embodiment of the present invention.

FIG. 6 is a schematic top view of a seal according to an embodiment of the present invention.

In the figure:

1. a film plate; 2. a first blank member; 21. an open end; 22. sealing the end; 23. an extension edge; 3. trimming the upper die; 31. a first body; 32. a first convex portion; 4. trimming the lower die; 41. a second body; 42. a second accommodating groove; 43. shearing a step; 5. stamping an upper die; 51. a third body; 52. a third accommodating groove; 53. a second convex portion; 6. stamping a lower die; 61. a fourth body; 62. a fourth accommodating groove; 7. a seal member; 71. a pipe body; 72. folding the edges inwards; 73. a connecting portion; 8. a second blank member.

Detailed Description

In order to make the technical problems solved, technical solutions adopted and technical effects achieved by the present invention clearer, the technical solutions of the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via 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.

As shown in fig. 5 and 6, the method for forming a battery seal according to the embodiment of the invention is mainly used for forming a seal 7 of an ultra-thin button battery with an inner folded edge 72, specifically, the seal 7 includes a tubular body 71 in a circular tube shape, a connecting portion 73 extends towards the center on an end surface of one end of the tubular body 71, one end of the connecting portion 73 away from the tubular body 71 is connected with the inner folded edge 72, the inner folded edge 72 extends towards the inside of the tubular body 71, and the inner folded edge 72 is parallel to the inner wall of the tubular body 71.

As shown in fig. 1 to 6, a battery seal molding method according to an embodiment of the present invention includes the steps of:

s100, extrusion molding, namely molding the master batch into a platy thin film plate 1 in an extrusion mode;

step S200, performing, namely stamping the film plate 1 into a first blank piece 2 by adopting a pre-stamping die, wherein the first blank piece 2 is of a cylindrical structure with one open end and one sealed end, and an extending edge 23 extends outwards from the open end 21 of the first blank piece 2;

step S300, trimming, removing the extending edge 23 and part of the sealing end 22, and forming a second blank member 8;

step S400, press forming, in which the remaining sealing end 22 of the second blank member 8 is folded inward by using a press die to form the sealing member 7.

The sealing element 7 with extremely thin thickness can be produced by adopting the combination of extrusion forming, preforming, trimming and stamping forming, the utilization rate of materials is improved, and the manufacturing cost of the sealing element 7 is greatly reduced. Compared with the prior art, the invention completely cancels the step of injection molding, does not need to design a high-cost injection mold, simultaneously avoids material waste in the injection molding process, improves the utilization rate of the material, and can realize the extremely thin thickness of the film plate 1 in an extrusion molding mode, thereby ensuring that the wall thickness of the molded sealing element 7 can be extremely thin and improving the energy density of the button cell.

The film plate 1 is manufactured by adopting a film manufacturing method, the film plate 1 with the set required thickness is obtained through feeding, heating extrusion, inflation traction and cooling in sequence, and technological parameters are controlled in the extrusion forming process, wherein the specific technological parameters are determined according to materials, for example, when a base material is a PFA material, the extrusion temperature is 300-350 ℃, and the cooling speed is 10-50 ℃/min. PFA plastic is a copolymer of a small amount of perfluoropropyl, perfluorovinyl ether and polytetrafluoroethylene, the fusion cohesiveness is enhanced, the melt viscosity is reduced, and the performance is unchanged compared with that of the polytetrafluoroethylene. The resin can be directly processed into products by adopting a common thermoplastic molding method. It is suitable for making corrosion-resistant parts, wear-resistant parts, sealing parts, insulating parts, medical apparatus parts, high-temperature wire and cable insulating layers, corrosion-resistant equipment, sealing materials, pump valve liners and chemical containers.

In the present embodiment, the film sheet member 1 is subjected to thinning processing at the time of preforming so that the thickness of the first blank member 2 after preforming coincides with the thickness of the sealing member 7. The thickness of the extruded thin film plate 1 is 0.05-0.4 mm, preferably 0.1mm, and the first blank 2 after preforming can reach 0.01mm by performing stamping and stretching through a preforming die during preforming.

Further, during preforming, the first blank part 2 is formed in a stamping and extending mode, the preforming temperature during preforming is 300-350 ℃, the pressing-down speed of preforming is 5-10 mm/min, and the preforming pressure is 0.3-0.7 MPa. Preferably, the preforming temperature during preforming is 300 ℃, the pressing speed of preforming is 6mm/min, and the preforming pressure is 0.3 MPa.

Carry out attenuate processing when preforming, can make the degree of difficulty of film plate 1 when the extrusion can reduce, and be difficult for causing film plate 1 damaged.

In a preferred embodiment of the invention, the second blank member 8 is subjected to a thinning process during the press forming to form the sealing member 7.

Further, the upper stamping die 5 and the lower stamping die 6 are heated before the upper stamping die 5 and the lower stamping die 6 of the stamping die are assembled, and in the process of assembling the upper stamping die 5 and the lower stamping die 6, the upper stamping die 5 and the lower stamping die 6 jointly extrude the positions of the second blank 8 so as to realize thinning treatment.

Specifically, step S400 includes the following steps:

step S410, sleeving the second blank 8 outside the lower stamping die 6, and enabling the remaining sealing end 22 to protrude out of the upper end of the lower stamping die 6;

step S420, heating the lower stamping die 6 and the upper stamping die 5 simultaneously;

step S430, slowly pressing down the upper punch mold 5 until the upper punch mold 5 and the lower punch mold 6 are closed to mold the seal 7.

In this embodiment, the upper stamping die 5 of the stamping die comprises a third main body 51, a third receiving groove 52 is concavely formed on one side of the third main body 51, a second protrusion 53 is convexly formed on the bottom of the third receiving groove 52, the outer periphery of the second protrusion 53 is spaced apart from the groove wall of the third receiving groove 52 by a distance of L1, the lower stamping die 6 comprises a fourth main body 61, one end of the fourth main body 61 can be inserted into the third receiving groove 52, the outer wall of the fourth main body 61 is spaced apart from the groove wall of the third receiving groove 52 by a distance of L2, L2 is matched with the required wall thickness of the tube 71 of the sealing member 7, L2 is smaller than the wall thickness of the extruded film plate 1, a fourth receiving groove 62 is concavely formed on one side of the fourth main body 61 close to the upper stamping die 5, when the upper stamping die 5 and the upper stamping die 6 are assembled, the end of the lower stamping die 6 is inserted into the third receiving groove 52, and the second protrusion 53 is inserted into the fourth receiving groove 62, the depth of the fourth receiving groove 62 is greater than the height of the second protrusion 53, the distance between the peripheral part of the second protrusion 53 and the groove wall of the fourth receiving groove 62 is L3, the L3 matches the required wall thickness of the tube 71 of the sealing member 7, and the L3 is smaller than the wall thickness of the extruded film plate 1.

In order to ensure that all positions of the second blank 8 can be pressed by the upper and lower stamping dies 5, 6, the third receiving groove 52 has a groove depth which is greater than the required overall height of the seal 7.

In this embodiment, the process parameters of the stamping forming are controlled as follows: when in punch forming, the punching temperature of the upper punching die 5 and the lower punching die 6 is 100-200 ℃, the pressing speed of the upper punching die 5 is 5-10 mm/min, and the pressing force of the upper punching die 5 is 0.3-0.7 MPa.

Preferably, the stamping temperature of the upper stamping die 5 and the lower stamping die 6 is 150 ℃, the pressing speed of the upper stamping die 5 is 5mm/min, and the pressing force of the upper stamping die 5 is 0.45 MPa.

In addition, when the thinning process is not at the press-forming stage, the lower punch mold 6 is not subjected to the heat treatment, and the distance L2 between the outer wall of the fourth body 61 and the groove wall of the third accommodation groove 52 is slightly larger than the thickness of the seal 7, and the distance L1 between the outer periphery of the second projection 53 and the groove wall of the third accommodation groove 52 is also slightly larger than the thickness of the seal 7.

Of course, the thickness of the film plate member 1 may be controlled to be equal to the desired thickness of the sealing member 7 directly during the extrusion molding, without being limited to the case where the sealing member 7 is formed to have a predetermined thickness by performing the thinning process in the preforming or the press molding after the extrusion molding.

In another preferred embodiment of the present invention, the extending edge 23 and a portion of the closed end 22 are removed by stamping during the trimming step. The trimming cut is smooth in a stamping mode, the trimming speed is high, the precision is high, and the batch production is facilitated.

In this embodiment, the extension edge 23 and a part of the sealing end 22 are removed by using a trimming mold, the trimming mold comprises a trimming upper mold 3 and a trimming lower mold 4, the trimming upper mold 3 comprises a first body 31, a first accommodating groove is concavely arranged on one side of the first body 31, a first convex portion 32 for punching the part of the sealing end 22 is convexly arranged at the center of the bottom of the first accommodating groove, the trimming lower mold 4 comprises a second body 41 matched with the first accommodating groove, a second accommodating groove 42 is concavely arranged on the second body 41, the first convex portion 32 can be inserted into the second accommodating groove 42, and a shearing step 43 for removing the extension edge 23 is annularly arranged on the outer periphery of the second body 41.

The width of the shearing step 43 is equal to the wall thickness of the tubular structure of the first blank member 2.

The distance between the outer wall of the trimming lower die 4 and the groove wall of the second receiving groove 42 matches the width of the remaining sealing end 22, and during punching, the peripheral portion of the first protrusion 32 is closely attached to the groove wall of the second receiving groove 42, so that the middle portion of the sealing end 22 is removed by the punching force of the first protrusion 32.

In a further preferred embodiment of the present invention, when the thinning process is performed in the press forming stage, after the upper press die 5 and the lower press die 6 are clamped, the seal 7 is gradually formed, and after the formation of the seal 7 is completed, the seal needs to be removed from the die, and in this embodiment, the upper press die 5 and the lower press die 6 are first separated from each other during the removal of the die, and after the cooling time T, the seal 7 on the lower press die 6 is removed. The time T is determined according to the cooling rate of the actual punch lower die 6, and is usually 10 min.

Of course, the mold release sequence is not limited to the above embodiment, and in another embodiment, the upper punch 5 and the lower punch 6 may be separated from each other and the seal 7 may be removed after the upper punch 5 and the lower punch 6 are completely cooled while keeping the upper punch 5 and the lower punch 6 in a clamped state. Therefore, the sealing element 7 can be kept in shape, the sealing element 7 is prevented from deforming after the upper stamping die 5 and the lower stamping die 6 are separated, and the manufacturing precision is improved.

When the thinning process is not performed in the press molding stage and the mold release is necessary, the upper press mold 5 and the lower press mold 6 are separated, and the seal 7 is taken out.

In the description herein, it is to be understood that the terms "upper" and the like are based on the orientation or positional relationship shown in the drawings, which are for convenience of description and simplicity of operation, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the present invention.

In the description herein, references to the term "an embodiment" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single technical solution, and such description is for clarity only, and those skilled in the art should take the description as a whole, and the technical solutions in the embodiments may be appropriately combined to form other embodiments that may be understood by those skilled in the art.

The technical principle of the present invention is described above in connection with specific embodiments. The description is made for the purpose of illustrating the principles of the invention and should not 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 inventive effort, which would fall within the scope of the present invention.

Claims

1. A method of forming a battery seal, comprising the steps of:

s100, carrying out extrusion forming, namely forming a plate-shaped film plate by using a master batch in an extrusion mode, wherein the master batch is thermoplastic;

s400, performing punch forming, namely inwards folding the residual sealing end of the second blank piece by adopting a stamping die to form a sealing piece;

and thinning the film plate during preforming to enable the thickness of the preformed first blank to be consistent with that of the sealing element.

2. The method of claim 1, wherein the extending edge and a portion of the sealing end are removed by stamping.

3. The method of claim 2, wherein the extended edge and a portion of the sealing end are removed by using a trimming mold, the trimming mold comprises an upper trimming mold and a lower trimming mold, the upper trimming mold comprises a first body, a first receiving groove is concavely formed on one side of the first body, a first protrusion for punching a portion of the sealing end is convexly formed at a center of a bottom of the first receiving groove, the lower trimming mold comprises a second body matched with the first receiving groove, a second receiving groove is concavely formed on the second body, the first protrusion is inserted into the second receiving groove, and a cutting step for removing the extended edge is formed at an outer circumferential ring of the second body.

4. The battery seal forming method according to claim 1, wherein the second blank member is subjected to thinning processing at the time of the press-forming to form the seal member.

5. The method of claim 4, wherein the upper and lower stamping dies are heated before the upper and lower stamping dies of the stamping die are closed, and the upper and lower stamping dies co-extrude the second blank at various locations during the closing of the upper and lower stamping dies to achieve the thinning process.

6. The battery seal molding method according to claim 5, wherein the step S400 comprises the steps of:

7. The method for forming a battery sealing member according to any one of claims 1 to 6, wherein the preforming temperature during preforming is 300 to 350 ℃, the pressing speed of the preforming is 5 to 10mm/min, and the pressure of the preforming is 0.3 to 0.7 MPa.

8. The method for forming a battery sealing member according to any one of claims 1 to 6, wherein a stamping temperature of an upper stamping die of the stamping die during stamping is 100 to 200 ℃, a pressing speed of the upper stamping die is 5 to 10mm/min, and a pressing force of the upper stamping die is 0.3 to 0.7 MPa.