Patent Description:
The present invention relates to a pouch curl prevention apparatus capable of applying stress to curls formed at an edge of a cup portion by pressing of a punch in a pouch forming process, which is recognized as an important problem in the present invention, in an opposite direction to alleviate the formed curls and being easily applicable to a conventional pouch forming process.

With increasing demand for portable electronic devices, such as a smartphone, a tablet, and a laptop computer, demand for secondary batteries as energy sources thereof has also abruptly increased. Thereamong, a lithium secondary battery, which has high energy density and a long battery lifespan, has been most widely used.

The lithium secondary battery includes an electrode assembly, configured such that a positive electrode sheet having a positive electrode active material applied thereto and a negative electrode sheet having a negative electrode active material applied thereto are disposed in the state in which a separator is interposed therebetween, and a battery case configured to receive the electrode assembly together with an electrolytic solution in a sealed state. Depending on the shape of a sheathing member, the lithium secondary battery may generally be classified as a can-shaped secondary battery having an electrode assembly mounted in a metal can or a pouch-shaped secondary battery having an electrode assembly mounted in a pouch made of an aluminum laminate sheet.

In a process of manufacturing the pouch-shaped secondary battery, in order to reduce a dead space in a battery cell while stably mounting and fixing the electrode assembly, which has a predetermined volume, in the battery case, a process of forming an electrode assembly receiving portion in the laminate sheet is generally performed using a deep drawing apparatus.

Documents <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT> concern methods and devices for forming a pouch film.

<FIG> is an exploded perspective view schematically showing the construction of a general pouch-shaped secondary battery.

Referring to <FIG>, the pouch-shaped secondary battery, which is a single cup type pouch-shaped secondary battery, includes a pouch case <NUM> made of an aluminum laminate sheet and a cell assembly <NUM> received in the pouch case <NUM>, the cell assembly being configured such that a plurality of electrochemical cells, each of which includes a positive electrode, a separator, and a negative electrode, is stacked. As shown in <FIG>, the pouch case <NUM> is a single cup type pouch case configured such that connection is achieved at one edge thereof. The pouch case <NUM> includes an upper pouch film <NUM> (a) and a lower pouch film <NUM> (b). A cup portion <NUM> configured to allow the cell assembly <NUM> to be seated therein is formed in the lower pouch film <NUM>(b). The cup portion <NUM>, which has a shape corresponding to the shape of the cell assembly <NUM>, is formed in the lower pouch film <NUM>(b) through a forming process, wherein the depth h of the cup portion is set depending on the thickness of the cell assembly <NUM>.

<FIG> is a process view showing a forming process in which a pouch film forming apparatus <NUM> forms a receiving portion in a pouch film <NUM>. (a) of <FIG> is a forming process plan view, and (b) of <FIG> is a forming process side view.

Referring to <FIG>, the pouch film forming apparatus <NUM> includes a punch <NUM>, a stripper <NUM>, and a die <NUM>. The die <NUM> is provided with a seating recess (not shown) having a shape corresponding to the shape of a desired pouch case when the pouch case is formed using the pouch film <NUM>. At this time, the depth of the seating recess corresponds to the depth of a receiving portion to be formed in the desired pouch case. In order to form a pouch case having a receiving portion of a desired depth using the pouch film <NUM>, the punch <NUM> applies pressure to the pouch film <NUM> disposed on the die <NUM>. That is, the punch presses the pouch film to form the pouch case.

During such a forming process, curls are generated at the pouch film, and defects occur due to curls in cutting and sealing processes after the pouch case forming process, whereby quality of a secondary battery is deteriorated.

Patent Document <NUM>, which relates to a process of forming an electrode assembly receiving portion using a deep drawing apparatus capable of adjusting the tensile force of a laminate sheet, discloses technology in which a roller unit is located at an upper surface adjacent to an edge of a cup portion of a pouch in a forming process, the roller unit moves the laminate sheet, a second gripper side is pressed, whereby tensile force applied to the laminate sheet is reduced, and therefore wrinkles are prevented when the laminate sheet is pressed by a punch.

Patent Document <NUM> discloses technology in which, in order to prevent generation of curls through rolling of a plurality of rollers in a cutting process to cut a part of an edge of a pouch after forming, a plurality of upper roller and lower roller pairs capable of rolling in contact with upper and lower surfaces adjacent to opposite edges of a pouch-shaped secondary battery is provided, a support frame configured to support a roller assembly is provided, the upper and lower rollers are located so as to correspond to each other, and a rolling operation is performed with respect to the upper and lower surfaces adjacent to the opposite edges of the pouch-shaped secondary battery, whereby stress is removed, thus preventing generation of curls.

However, a pouch curl prevention apparatus capable of applying stress to curls formed at an edge of a cup portion by pressing of a punch in a pouch forming process, which is recognized as an important problem in the present invention, in an opposite direction to alleviate the formed curls and being easily applicable to a conventional pouch forming process has not yet been proposed.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a pouch curl prevention apparatus capable of applying stress to curls formed at an edge of a pouch in a pouch film forming process in an opposite direction to alleviate or remove the curls and being easily applicable to a conventional pouch film forming process.

A pouch curl prevention apparatus according to the present invention to accomplish the above object is located at the rear of a pouch film forming apparatus and includes an upper roller assembly (<NUM>) including an upper roller (<NUM>) and a lower roller assembly (<NUM>) including a lower roller (<NUM>), wherein the upper roller (<NUM>) and the lower roller (<NUM>) are located so as to face each other, at least one of the upper roller (<NUM>) and the lower roller (<NUM>) is rotatable, and an upper roller unit (<NUM>) and a lower roller unit (<NUM>) are configured to pass a pouch film supplied from the pouch film forming apparatus therebetween.

The upper roller (<NUM>) and the lower roller (<NUM>) may be located so as to face each other in a state of being spaced apart from each other by a predetermined distance, and a pouch edge of the pouch film supplied from the pouch film forming apparatus may pass between the upper roller (<NUM>) and the lower roller (<NUM>).

The upper roller assembly (<NUM>) may include a pair of upper rollers (<NUM>) located spaced apart from each other by a predetermined distance, the lower roller assembly (<NUM>) may include a pair of lower rollers (<NUM>) located spaced apart from each other by a predetermined distance, and the pair of upper rollers (<NUM>) and the pair of lower rollers (<NUM>) may be located so as to face each other in a state of corresponding to each other.

The upper roller assembly (<NUM>) may include a position change portion (<NUM>) of the upper roller.

The position change portion (<NUM>) may include a plurality of recessed portions (<NUM>) configured to allow an upper roller shaft (<NUM>) of the upper roller unit (<NUM>) to be mounted therein.

The position of the recessed portion (<NUM>) in which the upper roller shaft (<NUM>) is mounted may be changed to adjust the distance between the upper roller (<NUM>) and the lower roller (<NUM>).

The distance between the pair of upper rollers (<NUM>) or the distance between the pair of lower rollers (<NUM>) may be adjustable.

The upper roller assembly (<NUM>) may include a vertical support portion (<NUM>) configured to be movable upwards and downwards in order to adjust the height of the upper roller unit (<NUM>).

The lower roller assembly (<NUM>) may include a lower roller fixing portion (<NUM>), and the lower roller fixing portion (<NUM>) may be provided with a position adjustment member configured to adjust the up and down position of the lower roller.

At least one of the upper roller (<NUM>) and the lower roller (<NUM>) located so as to face each other may be made of an elastic material.

In addition, the present invention may provide possible combinations of the above solving means.

As is apparent from the above description, it is possible to apply stress curls generated at an edge of a pouch cup portion formed in a pouch film forming process according to the present invention in an opposite direction, whereby it is possible to alleviate or remove the generated curls.

A pouch curl prevention apparatus according to the present invention is applied to produce pouch cases with improved quality, whereby it is possible to reduce a defect rate in a subsequent process and to manufacture a high-quality pouch-shaped secondary battery.

The pouch curl prevention apparatus according to the present invention is easily applicable to a conventional pouch film forming process, whereby it is possible to improve economic efficiency in the pouch film forming process.

In addition, all numeric ranges include the lowest value, the highest value, and all intermediate values therebetween unless the context clearly indicates otherwise.

Hereinafter, a pouch curl prevention apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

<FIG> is a process view showing a pouch film forming process using a pouch curl prevention apparatus according to an embodiment of the present invention. In <FIG>, (c) is a process plan view, and (d) is a process side view.

Referring to <FIG>, the pouch curl prevention apparatus according to the present invention is located so as to be used after a step of forming a pouch film to form a cup portion in a pouch film forming process, and specifically is located at the rear of a pouch film forming apparatus <NUM> in a transfer direction of the pouch film <NUM>.

In the present invention, the pouch film <NUM> may be a laminate sheet having a structure in which insulative layers each made of a polymer material are joined to opposite surfaces of a metal layer. Each of the insulative layers may have a thickness of approximately <NUM> to <NUM>, and may be coated or laminated on the metal layer. An upper one of the insulative layers is a polymer film layer that is thermally fusible, and a lower one of the insulative layers is a polymer film layer that functions as an outer protective layer. Meanwhile, the metal layer may be made of any one selected from among an alloy of iron, carbon, chromium, and manganese, an alloy of iron, chromium, and nickel, aluminum, or an equivalent thereto, and aluminum metal foil is widely used.

The pouch film forming apparatus <NUM> may include a die <NUM> configured to allow the pouch film <NUM> to be disposed thereon, a stripper <NUM> configured to press the pouch film <NUM> disposed on the die <NUM> in order to fix the pouch film <NUM>, and a punch <NUM> configured to press the pouch film <NUM> disposed on the die <NUM> in order to shape an electrode assembly receiving portion. In addition, the pouch film forming apparatus may include a working table (not shown) configured to support the above-described components and to transfer the pouch film <NUM> to a subsequent process.

As shown in <FIG>, the die <NUM> is configured to allow the pouch film <NUM> to be disposed thereon, and a die holder (not shown) configured to fix the die <NUM>, on which the pouch film <NUM> is disposed, may be included. Here, the die <NUM> has a smaller area than the die holder (not shown), and is provided in an upper surface thereof with a shaping portion (not shown) configured to shape a cup portion that receives an electrode assembly in the pouch film <NUM>.

The stripper <NUM>, which is configured to fix the pouch film disposed on the die <NUM>, may be provided above the die <NUM> so as to be movable upwards and downwards, and may press the pouch film <NUM> disposed on the die <NUM> so as to be fixed when being moved downwards. The stripper <NUM> may have a size corresponding to the size of the upper surface of the die <NUM>, and may be provided in an upper surface thereof with a through-hole (not shown) having the same size as the shaping portion (not shown) provided in the die <NUM>.

The punch <NUM> is provided above the die <NUM> so as to be movable upwards and downwards, and is inserted into the shaping portion to shape an electrode assembly receiving portion in the pouch film <NUM> when being moved downwards. A driving unit (not shown) configured to move the punch <NUM> in an upward-downward direction is included. The punch <NUM> is moved downwards by the driving unit, passes through the through-hole of the stripper <NUM>, and is inserted into the shaping portion. At this time, the punch is inserted into the shaping portion in the state in which the pouch film <NUM> located in the shaping portion is pressed, whereby it is possible to shape an electrode assembly receiving portion having a shape corresponding to the shape of the shaping portion in the pouch film <NUM>. After shaping of the receiving portion, the die <NUM> and the stripper <NUM> are moved upwards, the pouch film <NUM> having the cup portion configured to receive the electrode assembly formed therein is transferred rearwards by a pouch film transfer member (not shown), and curls formed at a pouch edge are alleviated or removed by the pouch curl prevention apparatus located at the rear. The pouch edge may be a part of the pouch film <NUM> in which the cup portion configured to receive the electrode assembly is not formed, specifically a non-forming part of the pouch film <NUM> from opposite peripheries of the pouch film to a periphery of the cup portion located parallel to the peripheries of the pouch film.

In the present invention, the pouch curl prevention apparatus is located at the rear of the pouch film forming apparatus <NUM> in the transfer direction of the pouch film <NUM>.

Referring to <FIG>, the pouch curl prevention apparatus includes a pair of upper rollers <NUM> and a pair of lower rollers <NUM> located spaced apart from each other by a predetermined distance in a lateral direction (y-axis direction) of the pouch film <NUM>.

The punch <NUM> and the shaping portion (not shown) of the die <NUM> of the pouch film forming apparatus <NUM> are located between the two upper rollers <NUM> and between the two lower rollers <NUM> in the lateral direction (y-axis direction) of the pouch film <NUM>. In addition, the pair of upper rollers <NUM> and the pair of lower rollers <NUM> are located at the edge of the cup portion configured to receive the electrode assembly formed by the pouch film forming apparatus <NUM> in the lateral direction (y-axis direction) of the pouch film <NUM>.

<FIG> is a perspective view of the pouch curl prevention apparatus according to the embodiment of the present invention, <FIG> is a front view and a partial enlarged view of the pouch curl prevention apparatus according to the embodiment of the present invention, and <FIG> is a side view and a partial enlarged view of the pouch curl prevention apparatus according to the embodiment of the present invention.

The pouch curl prevention apparatus according to the present invention will be described with reference to <FIG>.

The pouch curl prevention apparatus according to the present invention receives the pouch film having the cup portion configured to receive the electrode assembly formed therein from the pouch film forming apparatus <NUM>, rolls opposite surfaces of the pouch films at the edge of the cup portion using rollers to apply stress to curls formed at the pouch film in the pouch film forming process in an opposite direction, thereby alleviating or removing the curls. Here, a driving unit configured to transfer the pouch film may be provided. In addition, a driving unit configured to individually drive each unit component of the pouch curl prevention apparatus may be separately provided.

The pouch curl prevention apparatus may include an upper roller assembly <NUM> and a lower roller assembly <NUM>.

First, the lower roller assembly <NUM> will be described.

The lower roller assembly <NUM> includes a lower frame <NUM> coupled and fixed to the working table (not shown) of the pouch film forming apparatus <NUM>. The lower frame <NUM> may include a vertical lower frame portion (not shown) coupled to the working table (not shown) of the pouch film forming apparatus <NUM> and a horizontal lower frame portion (not shown) located parallel to a wide surface of the pouch film <NUM> that passes through an upper end of the lower frame <NUM>. Specifically, the horizontal lower frame portion (not shown) may be disposed perpendicular to the transfer direction (x-axis direction) of the pouch film <NUM>. A lower roller unit <NUM> may be located at the lower frame <NUM> in a state of being fixed thereto. Specifically, a pair of lower roller fixing portions <NUM> may be located in a direction toward an upper part of the horizontal lower frame portion so as to be spaced apart from each other by a predetermined distance, and a lower roller shaft <NUM> may be located at the lower roller fixing portions <NUM> to fix a lower roller <NUM> to the lower roller fixing portions <NUM>.

The lower roller <NUM> may be formed in the shape of a cylinder and may have a through-hole formed in a direction toward a central axis of the cylinder such that the lower roller shaft <NUM> extends through the through-hole. The lower roller <NUM> is rotatable about the lower roller shaft <NUM>. The rotational direction of the lower roller <NUM> may be identical to or opposite the transfer direction of the pouch film <NUM>. In addition, a central axis of the lower roller <NUM> may be located parallel to the lateral direction (y-axis direction) of the pouch film <NUM>.

The pouch edge of the pouch film <NUM> supplied from the pouch film forming apparatus <NUM> is transferred rearwards in face-to-face contact with an outer circumferential surface of the lower roller <NUM>. Here, the material for the lower roller <NUM> is not particularly restricted as long as the lower roller is capable of applying stress to the pouch film <NUM> that faces the lower roller. Specifically, the lower roller may be made of an elastic material, more specifically a rigid elastic material.

Here, each of the lower roller fixing portions <NUM> is provided with an up and down position adjustment member configured to adjust the up and down position of the lower roller shaft <NUM> in a vertical direction (z-axis direction). As a result, the deformation angle of the pouch edge of the pouch film <NUM> that is horizontally transferred when passing through an upper end of an outer circumferential surface of the lower roller <NUM> may be changed. Consequently, reverse curls are differently formed depending on the extent of pouch curls formed during forming of the pouch film <NUM> at the front end, which is advantageous to alleviation or removal of the pouch curls.

Next, the upper roller assembly <NUM> will be described.

The upper roller assembly <NUM> may be located above the lower roller assembly <NUM>. The upper roller assembly <NUM> may include an upper frame <NUM>, wherein the upper frame <NUM> may include a horizontal upper frame portion (not shown) located parallel to the horizontal lower frame portion and a vertical upper frame portion (not shown). The vertical upper frame portion is coupled to an upper part of the horizontal lower frame portion.

A vertical support portion <NUM> and a horizontal support portion <NUM> coupled and connected to the vertical support portion <NUM> may be located in a direction toward a lower end of the horizontal upper frame portion. The vertical support portion <NUM> may be formed in an upward and downward movable structure, and may adjust the up and down position of the horizontal support portion <NUM> connected thereto.

The upper roller assembly <NUM> may include a position change portion <NUM>. The position change portion <NUM> may be located at each of opposite ends of the horizontal support portion <NUM>. The position change portion <NUM> may be formed in a plate shape. Specifically, a through-hole (not shown) having a blocked arc shape may be formed in a central part of the position change portion such that an upper roller shaft <NUM>, a description of which will follow, extends through the through-hole. Here, a recessed portion <NUM> may be formed in a lower end of the through-hole, and the upper roller shaft <NUM> may be mounted in the recessed portion <NUM>. A plurality of recessed portions <NUM> may be formed spaced apart from the center of the through-hole (not shown) having the blocked arc shape by a predetermined angle. The predetermined angle may be <NUM>° or less, specifically <NUM>° or less. In addition, the recessed portions <NUM> may be in symmetry with respect to a central axis of the arc-shaped through-hole in a vertical direction.

An upper roller unit <NUM> may be mounted in the through-holes of the pair of position change portions <NUM>. The upper roller unit <NUM> includes an upper roller shaft <NUM> mounted in the pair of position change portions <NUM> and a pair of upper rollers <NUM>, through which the upper roller shaft <NUM> extends, the pair of upper rollers being located so as to correspond to the pair of lower rollers <NUM>. A predetermined distance is defined between an outer circumferential surface of the lower roller <NUM> and an outer circumferential surface of the upper roller <NUM> that face each other, and the pouch edge of the pouch formed by the pouch film forming apparatus <NUM> may pass between the outer circumferential surfaces. In the same manner, the material for the upper roller <NUM> is not particularly restricted as long as the upper roller is capable of applying stress to the pouch film <NUM> that faces the upper roller. Specifically, the upper roller may be made of an elastic material, more specifically a rigid elastic material.

Here, the upper roller <NUM> and the lower roller <NUM> may be rotated in the transfer direction of the pouch film <NUM> or a direction oppoiste thereto, and a separate driving portion and controller configured to rotate the upper roller <NUM> and the lower roller <NUM> at a predetermined speed may be provided.

The horizontal position of the upper roller <NUM> or the lower roller <NUM> may be changed. This is advantageous to adjustment of the area of the pouch edge that passes between the upper roller <NUM> and the lower roller <NUM>.

Opposite ends of the upper roller shaft <NUM> may be mounted in the recessed portions <NUM> of the pair of position change portions <NUM>. In addition, the upper roller shaft <NUM> may be selectively located at any one of the plurality of recessed portions <NUM>. As described above, the position of the upper roller shaft <NUM> in the recessed portion <NUM> may be changed, whereby the distance between the upper roller <NUM> and the lower roller <NUM> that face each other may be changed, and therefore it is possible to change stress applied to the pouch edge that passes between the upper roller <NUM> and the lower roller <NUM>. Consequently, stress applied to the pouch edge may be changed depending on the extent of curls formed by the pouch film forming apparatus <NUM>, whereby it is possible to effectively alleviate or remove curls and at the same time to reduce stress applied to the pouch edge, which is advantageous to prevention of damage to the pouch edge in a subsequent process.

An upper roller shaft fixing portion <NUM> may be located at a side opposite the upper roller <NUM> in the state in which the position change portion <NUM> is disposed therebetween. After the position of the upper roller shaft <NUM> in the recessed portion <NUM> is changed, the fixing portion <NUM> fixes the upper roller shaft <NUM> to the position change portion <NUM>. As a result, it is possible to prevent change in relative position of the upper roller <NUM> and the lower roller <NUM> and distance therebetween due to movement of the upper roller shaft <NUM> in an upward-downward direction (z-axis direction) and a leftward-rightward direction (y-axis direction). This is advantageous to prevention of damage to the pouch edge due to non-uniform stress applied to the pouch edge that passes between the upper roller <NUM> and the lower roller <NUM>. The upper roller shaft fixing portion <NUM> may have a screw type shaft so as to be coupled to the upper roller shaft <NUM>.

Claim 1:
An assembly for forming a pouch film characterized in that it comprises a pouch curl prevention apparatus and a pouch film forming apparatus , said pouch curl prevention apparatus being located at a rear of a pouch film forming apparatus such that the pouch film forming apparatus supplies a pouch film (<NUM>) to the pouch curl prevention apparatus, wherein the pouch film forming apparatus comprises a punch (<NUM>), a stripper (<NUM>), and a die (<NUM>) having a seating recess, and
wherein the pouch curl prevention apparatus comprising:
an upper roller assembly (<NUM>) comprising an upper roller (<NUM>,<NUM>); and
a lower roller assembly (<NUM>) comprising a lower roller (<NUM>,<NUM>), wherein
the upper roller (<NUM>,<NUM>) and the lower roller (<NUM>,<NUM>) are located so as to face each other,
at least one of the upper roller (<NUM>) and the lower roller (<NUM>) is rotatable, and
wherein an upper roller unit (<NUM>) and a lower roller unit (<NUM>) are configured to pass the pouch film (<NUM>) supplied from the pouch film forming apparatus therebetween.