Abstract:
Provided is a fabricating apparatus for a secondary battery, the fabricating apparatus including: a base material supplier configured to supply a base material; a winder configured to wind the base material through a mandrel; and a controller configured to control a base material supply amount of the base material supplier and a mandrel rotation amount of the winder, wherein the controller is further configured to store a profile of the base material supply amount with respect to the mandrel rotation amount, and to synchronously control the base material supply amount and the mandrel rotation amount based on the profile.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2014-0099795 filed on Aug. 4, 2014 in the Korean Intellectual Property Office, the content of which in its entirety are herein incorporated by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Aspects of embodiments of the present invention relate to a fabricating apparatus and method for a secondary battery. 
         [0004]    2. Description of the Related Art 
         [0005]    Recently, use of portable devices, such as a mobile phone, a personal digital assistant (PDA), a net-book, or a notebook computer, are gradually increasing. The portable devices are supplied with power from rechargeable secondary batteries according to use characteristics. 
         [0006]    A secondary battery generally includes an electrode assembly including a positive electrode plate, a separator, and a negative electrode plate that are stacked and wound. 
         [0007]    To this end, winding is performed while a base material for forming each electrode plate is unwound from a spool around which the base material is wound. 
       SUMMARY 
       [0008]    During winding, it is desirable to maintain a tension of the base material at a constant or substantially constant level. If the tension is not maintained at a constant or substantially constant level during winding, deformation of the base material may occur within the electrode assembly. Therefore, it is desirable to develop a technique for maintaining the tension of the base material at a constant or substantially constant level, while supplying the base material. 
         [0009]    Aspects of embodiments of the present invention provide a fabricating apparatus and method for a secondary battery, which can reduce failures during winding of an electrode assembly. 
         [0010]    The above and other aspects and features of the present invention will be described in or be apparent from the following description of the example embodiments. 
         [0011]    According to an embodiment of the present invention, there is provided a fabricating apparatus for a secondary battery, the fabricating apparatus including: a base material supplier configured to supply a base material; a winder configured to wind the base material through a mandrel; and a controller configured to control a base material supply amount of the base material supplier and a mandrel rotation amount of the winder, wherein the controller is further configured to store a profile of the base material supply amount with respect to the mandrel rotation amount, and to synchronously control the base material supply amount and the mandrel rotation amount based on the profile. 
         [0012]    The profile may include the base material supply amount with a circumference variation corresponding to the mandrel rotation amount. 
         [0013]    The fabricating apparatus may further include a tension measurer configured to measure a tension of the base material between the base material supplier and the winder. 
         [0014]    The tension measurer may include a dancer system, a load cell, or a combination thereof. 
         [0015]    The fabricating apparatus may further include a base material supply amount measurer configured to measure the base material supply amount between the base material supplier and the winder. 
         [0016]    The base material supply amount measurer may include an encoder. 
         [0017]    The controller may be configured to control the base material supply amount corresponding to the mandrel rotation amount to control the tension of the base material. 
         [0018]    When the secondary battery includes a cylindrical battery, the profile may include a base material unit supply amount that gradually increases per turn of the mandrel. 
         [0019]    When the secondary battery includes a rectangular battery, the profile may include a base material unit supply amount appearing as two parabolas per turn of the mandrel. 
         [0020]    According to another embodiment of the present invention, there is provided a fabricating method for a secondary battery including an electrode assembly formed by winding a supplied base material, the method including: acquiring a profile of a base material supply amount of a base material supplier for supplying the base material with respect to a mandrel rotation amount of a winder for winding the base material; and synchronously driving the mandrel and the base material supplier based on the profile. 
         [0021]    The acquiring of the profile may include measuring the base material supply amount from the base material supplier as the mandrel is rotated. 
         [0022]    The acquiring of the profile may include measuring the base material supply amount utilizing a base material supply amount measurer while continuously rotating the mandrel. 
         [0023]    The acquiring of the profile may include measuring the base material supply amount by multiplying a roller diameter of the base material supplier with a rotation angle while rotating the mandrel. 
         [0024]    The fabricating method may further include: calculating the base material supply amount with respect to the mandrel rotation amount at a point of time of the profile to control the tension of the base material at the point of time; and controlling the calculated base material supply amount. 
         [0025]    When the secondary battery comprises a cylindrical battery, the profile may include a base material unit supply amount that gradually increases per turn of the mandrel. 
         [0026]    When the secondary battery comprises a rectangular battery, the profile may include a base material unit supply amount appearing as two parabolas per turn of the mandrel. 
         [0027]    As described above, in the fabricating apparatus and method for a secondary battery according to embodiments of the present invention, a profile indicating the relationship of the base material supply amount relative to the mandrel rotation amount of the winding unit is pre-stored, and the controller controls the mandrel and the base material supply unit at the same time, thereby immediately correcting the tension of the base material. 
         [0028]    In addition, in the fabricating apparatus and method for a secondary battery according to embodiments of the present invention, when it is necessary or desirable to correct the tension of the base material, the controller finely controls the base material supply amount with respect to the current mandrel rotation amount based on the profile, thereby maintaining the tension of the base material at a constant or substantially constant level during winding. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    The above and other aspects and features of the present invention will become more apparent by describing in detail example embodiments thereof with reference to the attached drawings in which: 
           [0030]      FIG. 1  is a block diagram of a fabricating apparatus for a secondary battery according to an embodiment of the present invention; 
           [0031]      FIG. 2  is a graph illustrating profiles of mandrel rotation amounts and base material supply amounts when a secondary battery is a cylindrical battery according to an embodiment of the present invention; 
           [0032]      FIG. 3  is a graph illustrating profiles of mandrel rotation amounts and base material supply amounts when a secondary battery is a rectangular battery according to an embodiment of the present invention; 
           [0033]      FIG. 4  is a flowchart illustrating a fabricating method for a secondary battery according to an embodiment of the present invention; 
           [0034]      FIG. 5  is a flowchart illustrating an example method of acquiring profiles of mandrel rotation amounts and base material supply amounts shown in  FIG. 4 ; and 
           [0035]      FIG. 6  is a flowchart illustrating another example method of acquiring profiles of mandrel rotation amounts and base material supply amounts shown in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0036]    Hereinafter, examples of embodiments of the invention will be described in detail with reference to the accompanying drawings, such that they can be made and used by those skilled in the art. 
         [0037]      FIG. 1  is a block diagram of a fabricating apparatus for a secondary battery according to an embodiment of the present invention. 
         [0038]    Referring to  FIG. 1 , the fabricating apparatus  100  for a secondary battery according to an embodiment of the present invention may include a base material supply unit  110  (e.g., a base material supplier) at an end of the fabricating apparatus  100  for supplying an electrode plate base material  10 , a winding unit  120  (e.g., a winder) at another end of the fabricating apparatus  100  for winding the base material  10 , a controller  130  for controlling the supplying and winding of the base material  10 , a dancer system  140  and a load cell  150  (e.g., a tension measurer) for measuring a tension of the supplied base material  10 , and a base material supply amount measuring unit  160  (e.g., a base material supply amount measurer) for measuring a supply amount of the base material  10 . 
         [0039]    The base material supply unit  110  may include a spool around which the electrode plate base material  10  is wound and/or a driving roller coupled (e.g., connected) to the spool. The base material supply unit  110  supplies the base material  10  by rotation, and accordingly, the base material  10  may be supplied at a constant or substantially constant speed (e.g., a predefined speed). 
         [0040]    The winding unit  120  is at an opposite side of the base material supply unit  110 , and winds the base material  10  supplied through a mandrel in a shape or configuration (e.g., a predetermined shape or configuration). For example, the winding unit  120  may wind the base material  10  in a cylindrical configuration for a cylindrical battery according to the shape of the mandrel, or in a flat or oval configuration for a rectangular battery. In addition, it is desirable for the winding unit  120  to wind the base material  10  with a constant tension during winding. 
         [0041]    The controller  130  controls the base material supply unit  110  and the winding unit  120  concurrently (e.g., at the same time or simultaneously), so that the base material  10  wound around the winding unit  120  can be wound with a constant or substantially constant tension. 
         [0042]    To this end, as will be described below, the controller  130  stores a profile corresponding to (e.g., indicating) the relationship between the mandrel rotation amount of the winding unit  120  and the base material supply amount of the base material supply unit  110 . The controller  130  controls concurrently (e.g., at the same time or simultaneously) the mandrel rotation amount of the winding unit  120  and the base material supply amount of the base material supply unit  110  based on the profile. Therefore, even if the mandrel rotation amount is accelerated or decelerated at a high speed, since the base material supply amount of the base material supply unit  110  is also controlled without delay, the tension of the base material  10  is not changed. In addition, since the controlling is performed based on the pre-stored profile, a separate sensing operation is not required, thereby preventing or reducing noises and delays in time from occurring during sensing and signal transfer processes. Accordingly, in the fabricating apparatus  100  for a secondary battery according to an embodiment of the present invention, the electrode assembly can be wound without causing deformation in the external shape, by maintaining the base material  10  at a constant or substantially constant tension level. 
         [0043]    In the fabricating apparatus  100  for a secondary battery according to an embodiment of the present invention, a tension measurer may include the dancer system  140  and the load cell  150  to measure the tension of the base material  10 . However, the present invention is not limited thereto, and the tension measurer may include either the dancer system  140  or the load cell  150 , or a combination of both the dancer system  140  and the load cell  150 . 
         [0044]    When the tension is applied to the base material  10  by changing a direction of the base material  10  roughly reversely through a first roller  11 , the dancer system  140  receives the base material  10 . The dancer system  140  is formed in the shape of a bar and may change the direction of the base material  10  roughly reversely through a roller  141  provided at a bottom end of the dancer system  140  to receive the base material  10 . The bottom end of the dancer system  140  is rotatable in a left-and-right direction with a top end being (e.g., used as) a rotation axis. In addition, the bottom end of the dancer system  140  is rotated according to the tension of the base material  10  to allow a constant or substantially constant level of tension to be applied to the base material  10 . In addition, the dancer system  140  includes a rotation angle sensor  142  provided at the top end of the dancer system  140  as the rotation axis, thereby measuring the tension of the base material  10  by measuring the rotation angle of the bottom end. 
         [0045]    The load cell  150  receives the base material  10  from the dancer system  140  through a second roller  12 . In addition, as shown in  FIG. 2 , the load cell  150  may change the direction of the base material  10  through three rollers  151 ,  152 , and  153 . For example, if the front and rear rollers  151  and  153  are positioned to allow the base material  10  to pass thereon, and the central roller  152  is positioned to allow the base material  10  to pass thereunder, an elastic member  154  (e.g., a spring) may be formed under the central roller  152 . Therefore, a force applied to the elastic member  154  varies according to the tension of the base material  10 , so that the load cell  150  may measure the tension of the base material  10 . 
         [0046]    The base material supply amount measuring unit  160  receives the base material  10  from the load cell  150  through a third roller  13 , and is positioned in front (e.g., immediately in front) of the winding unit  120 . The base material supply amount measuring unit  160  may include an encoder. The base material supply amount measuring unit  160  may measure an amount of the supplied base material  10 . At an initial setting stage of the fabricating apparatus  100  for a secondary battery according to an embodiment of the present invention, the base material supply amount measuring unit  160  is used to obtain profiles of the mandrel rotation amount and the base material supply amount. 
         [0047]    In more detail, the base material supply amount measuring unit  160  measures a length of the base material  10  received from the base material supply unit  110  at a front (e.g., immediately in front) of the mandrel, while rotating the mandrel of the winding unit  120  at an angle (e.g., predetermined angle). In addition, the controller  130  stores the profiles produced from data of the mandrel rotation amount and the base material supply amount. In addition, as described above, the controller  130  controls concurrently (e.g., at the same time or simultaneously) the mandrel rotation amount of the winding unit  120  and the base material supply amount of the base material supply unit  110  based on the stored profiles, thereby winding the electrode assembly with a constant or substantially constant level of tension. 
         [0048]    Hereinafter, profiles of the mandrel rotation amounts and the base material supply amounts in the fabricating method for a secondary battery according to an embodiment of the present invention will be described. 
         [0049]      FIG. 2  illustrates profiles of the mandrel rotation amounts and the base material supply amounts when a secondary battery according to an embodiment of the present invention includes a cylindrical battery, and  FIG. 3  illustrates profiles of the mandrel rotation amounts and the base material supply amounts when a secondary battery according to an embodiment of the present invention includes a rectangular battery. 
         [0050]    Referring to  FIG. 2 , when a secondary battery according to an embodiment of the present invention includes a cylindrical battery, a unit supply amount (the y axis in the right of the graph) with respect to a mandrel rotation angle (the x axis of the graph) gradually increases on the basis of a multiple of 360 degrees as the rotation angle, because the mandrel is in the shape of a cylinder and a winding circumference per turn of the base material  10  gradually increases due to the thickness of the base material  10 . In addition, a profile in which a cumulative supply amount (the y axis in the left of the graph) is roughly proportional to the mandrel rotation angle (the x axis of the graph) is generated. However, since the circumference gradually increases from the multiple of 360 degrees as the rotation angle in the cumulative supply amount, the profile of the cumulative supply amount is shaped to increase taking into consideration the mandrel rotation angle and the circumference increment. Since the thickness of the base material  10  is very small, the cumulative supply amount (the y axis in the left of the graph) is roughly linear. 
         [0051]    Referring to  FIG. 3 , when a secondary battery according to an embodiment of the present invention includes a rectangular battery (or prismatic battery), the unit supply amount (the y axis in the right of the graph) with respect to the mandrel rotation angle (the x axis of the graph) varies, such that approximately two parabolas are generated per turn (ranging from 0 to 360 degrees in rotation angle). Since the mandrel is roughly flat, the length of the base material  10  that is wound varies as the mandrel rotates 0 to 360 degrees. The upper limit of the parabola corresponds to the center of a longer side of the mandrel, and the lower limit of the parabola corresponds to a shorter side of the mandrel. In addition, the cumulative supply amount (the y axis in the left of the graph) with respect to the mandrel rotation angle (the x axis of the graph), which is obtained by accumulating the unit supply amount (the y axis in the right of the graph) in the unit of one turn, gradually increases according to the rotation of the mandrel. In this case, due to the thickness of the base material  10 , when the mandrel rotates, the base material supply amount is an amount taking into consideration an increment of the base material supply amount. However, since the thickness of the base material  10  is very small, the cumulative supply amount is roughly repeated in units of one turn of the mandrel. 
         [0052]    Hereinafter, a fabricating method for a secondary battery according to an embodiment of the present invention will be described with reference to  FIGS. 4 to 6 . 
         [0053]      FIG. 4  is a flowchart illustrating a fabricating method for a secondary battery according to an embodiment of the present invention,  FIG. 5  is a flowchart illustrating an example method of acquiring profiles of the mandrel rotation amounts and the base material supply amounts shown in  FIG. 4 , and  FIG. 6  is a flowchart illustrating another example method of acquiring profiles of the mandrel rotation amounts and the base material supply amounts shown in  FIG. 4 . 
         [0054]    Referring to  FIG. 4 , the fabricating method for a secondary battery according to an embodiment of the present invention may include acquiring profiles of the mandrel rotation amounts and the base material supply amounts (S 1 ), synchronously driving a mandrel and a base material supply unit based on the profiles (S 2 ), monitoring a tension of the supplied base material (S 3 ), and controlling the base material supply amount (S 4 ). 
         [0055]    The acquiring of the profiles for the mandrel rotation amounts and the base material supply amounts (S 1 ) includes acquiring the profiles obtained from data corresponding to the relationship between the mandrel rotation amount and the base material supply amount by measuring the base material supply amount by the base material supply amount measuring unit  160 , while the controller  130  rotates the mandrel of the winding unit  120  at an angle (e.g., predetermined angle) in the fabricating apparatus  100  for a secondary battery according to an embodiment of the present invention. 
         [0056]    In more detail, the acquiring of the profiles for the mandrel rotation amounts and the base material supply amounts (S 1 ) may be performed by continuously measuring the mandrel rotation amounts and the base material supply amounts through the process shown in  FIG. 5 . In the process shown in  FIG. 5 , the mandrel of the winding unit  120  is regularly positioned (S 11 ), and the dancer system  140  or the load cell  150  is set to a feedback mode (S 12 ). In the feedback mode, the dancer system  140  and the load cell  150  may maintain the tension applied to the base material  10  at a constant or substantially constant level, and the rotation of the base material supply unit  110  may be controlled according to the variation in the base material unit supply amount in order to maintain a constant or substantially constant tension level. 
         [0057]    In addition, data corresponding to the mandrel rotation angle of the winding unit  120  and the base material supply amount measuring unit  160  are reset for initialization (S 13 ), and the mandrel is continuously rotated at a constant or substantially constant speed (S 14 ). 
         [0058]    In addition, the base material supply amount measuring unit  160  monitors a length of the supplied base material  10  from the front (e.g., immediately in front) of the winding unit  120  (S 15 ), and the controller  130  finally measures data corresponding to the relationship between the base material supply amount and the mandrel rotation angle (S 16 ), thereby creating the profile. 
         [0059]    As shown in  FIG. 6 , the acquiring of the profiles of the mandrel rotation amounts and the base material supply amounts (S 1 ) may include intermittently measuring the mandrel rotation amounts and the base material supply amounts. 
         [0060]    First, the mandrel of the winding unit  120  is regularly positioned (S 11 ), the dancer system  140  or the load cell  150  is set to a feedback mode (S 12 ), and data corresponding to the relationship between the mandrel rotation amount of the winding unit  120  and the base material supply amount of the base material supply amount measuring unit  160  are reset for initialization (S 13 ), which are the same or substantially the same with those in the continuous measuring of the mandrel rotation amounts and the base material supply amounts, as shown in  FIG. 5 . 
         [0061]    However, in the intermittent measuring, the mandrel of the winding unit  120  is rotated by an angle (e.g., predetermined angle) to be stopped (S 14 ), and a length of the supplied base material  10  is monitored (S 15 ). The length of the base material  10  may be monitored by (e.g., using) the base material supply amount measuring unit  160 . In some cases, the length of the base material  10  may be calculated by multiplying a roller diameter of the base material supply unit  110  with a rotation angle. 
         [0062]    In addition, the controller  130  controls the base material supply amount measuring unit  160  to measure the data corresponding to the relationship between the mandrel rotation amount and the base material supply amount (S 16 ), and the steps S 14  to S 16  are repeatedly performed, thereby acquiring a final profile. 
         [0063]    In addition, as described above, the profile may be shaped as shown in  FIG. 2  or  3 , according to the kind of secondary battery fabricated (e.g., cylindrical or rectangular). 
         [0064]    During the synchronous driving of the mandrel and the base material supply unit (S 2 ), the controller  130  synchronously drives the mandrel of the winding unit  120  and the base material supply unit  110  based on the acquired profile. In the synchronous driving of the mandrel and the base material supply unit (S 2 ), unlike in an existing feedback mode, since a time difference between a time of sensing the tension of the base material  10  and a time of controlling the base material supply amount is not necessarily taken into consideration, the synchronous driving of the mandrel and the base material supply unit  110  can be accurately achieved. 
         [0065]    During the monitoring of the tension of the supplied base material  10  (S 3 ), the controller  130  monitors the tension of the base material  10  through the tension measurer (e.g., the load cell  150 ) during the winding of the electrode assembly. Accordingly, the controller  130  may monitor whether or not the tension of the base material  10  is constant or substantially constant during the winding of the electrode assembly. 
         [0066]    During the controlling of the base material supply amount (S 4 ), in order to maintain the tension of the base material  10  at a constant or substantially constant level, the base material supply amount is controlled. If it is necessary or desirable to change the tension of the base material  10  during the winding, the controller  130  identifies a current mandrel angle of the winding unit  120 , and controls (e.g., finely controls) a unit supply amount of the base material supply unit  110 , corresponding to the current mandrel angle. For example, in order to increase the tension of the base material  10 , the unit supply amount of the base material  10  is reduced, and in order to reduce the tension of the base material  10 , the unit supply amount of the base material  10  is increased. 
         [0067]    While the fabricating apparatus and method for a secondary battery according to the present invention have been particularly shown and described with reference to example embodiments herein, it will be understood by those of ordinary skill in the art that various changes in form and details may be made, without departing from the spirit and scope of the present invention as defined by the following claims and their equivalents. It is therefore desired that the present embodiments be considered in all respects as illustrative and not restrictive, with reference being made to the appended claims and their equivalents, rather than the foregoing description, to indicate the spirit and scope of the present invention.