Patent Publication Number: US-9895869-B2

Title: Sheet material adhesive agent application method

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 14/424,319, filed Feb. 26, 2015, which is the National Stage of Application No. PCT/JP2013/070696 filed on Jul. 31, 2013, which claims benefit of priority from the prior Japanese Application No. 2012-185997, filed Aug. 27, 2012, the entire contents of all of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to a sheet material adhesive agent application method. 
     BACKGROUND ART 
     As is commonly known, when an uppermost one of multiple sheet materials stacked in a stocker is taken out sequentially, there is a request to prevent that two sheet materials are taken out simultaneously (i.e. double take-out of sheet materials). For example, a patent document 1 discloses a sheet material transfer device including a tool for preventing double take-out of sheet materials. 
     According to a technique described in patent document 1, a tool for preventing double take-out of sheet materials is provided which includes a hole slightly smaller than target sheets, and when a sheet is taken out from a stocker by a sheet take-out means, edge parts of the sheet is bent downwardly by passing the sheet through the tool. According to this method, it is said that the sheet materials can be reliably taken out one by one by leaving the uppermost sheet only and separating the other sheets by the sheet take-out means when two or more of the target sheet materials are stacked. 
     However, even if the technique described in patent document 1 can be applied to a flexible sheet such as paper or cloth, there is room for improvement because it is difficult to pass the sheet through the tool for preventing double take-out in a case of a relatively high rigidity sheet such as a resin sheet. 
     PRIOR ART DOCUMENT(S) 
     Patent Document(s) 
     Patent Document 1: Japanese Patent Application Publication No. 2000-168976. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a sheet material adhesive agent application method which can cancel an adverse effect of warpage of a sheet material, and thereby enhance the quality and stability of adhesive agent application. 
     According to one aspect of the invention, a sheet material adhesive agent application method comprises: 
     performing a first action including applying an adhesive agent to a sheet material; and performing a second action in advance to the first action, wherein the second action includes setting the sheet material so that the sheet material has a predetermined curvature; and wherein the first action is completed before the sheet material is restored to a state before the second action. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan diagram showing schematic configuration of an adhesive agent application line which employs a sheet material adhesive agent application. 
         FIG. 2  is an enlarged diagram viewed in a direction indicated by an arrow D in  FIG. 1 . 
         FIG. 3  is an enlarged diagram viewed in a direction indicated by an arrow C in  FIG. 1 . 
         FIG. 4  is a plan diagram of  FIG. 3 . 
         FIG. 5  is a partially enlarged diagram of  FIG. 3 . 
     
    
    
     MODE(S) FOR CARRYING OUT THE INVENTION 
     The drawings of  FIGS. 1 to 5  show specific embodiments of a sheet material adhesive agent application method according to the present invention.  FIG. 1  shows a schematic plan view of a line for applying an adhesive agent to sheet materials. 
     For example, the sheet material is made of resin such as PP (polypropylene), and has a rectangular shape, and has a thickness of about 1 millimeter, and has a property of electrical insulation. In this embodiment, it is assumed that the sheet material is used as an insulation sheet, when multiple cells are accommodated in a metallic hard case, and modularized to form a module of a lithium-ion secondary battery, wherein each cell has a thin laminated structure. The sheet material which functions as the insulation sheet is interposed by adhesive bonding between the cells and the hard case in the lithium-ion secondary battery in order to prevent direct contact therebetween. Accordingly, it is necessary to apply the adhesive agent to both surfaces of the sheet material in advance under a condition that the sheet material is separated.  FIG. 1  shows schematically an adhesive agent application line. 
     As shown in  FIG. 1 , an adhesive agent application line  1  is based on a conveyor  2 , including a sheet material input stage S 1 , an adhesive agent application stage (obverse side) S 2 , an obverse and reverse side reversal stage S 3 , an adhesive agent application stage (reverse side) S 4 , and a sheet material take-out stage S 5 , which are arranged from a starting end side. The sheet materials are conveyed sequentially in a direction from the starting end side to a terminal end side, wherein each sheet material is positioned and placed on a pallet not shown. 
     Moreover, sheet material stockers  3 A and  3 B are provided on respective sides of sheet material input stage S 1 . Multiple predetermined sheet materials are stacked in each sheet material stocker  3 A,  3 B. As described below, one of the sheet materials stacked in sheet material stocker  3 A or  3 B is taken out sequentially by a sheet material take-out means, and then the taken-out sheet material is positioned and input on a pallet on standby at sheet material input stage S 1 . 
       FIG. 2  shows a diagram viewed in a direction indicated by an arrow D in  FIG. 1 . As shown in  FIG. 2 , adhesive agent application stage S 2  is provided with an adhesive agent application apparatus  5  through a gate type frame  4  above conveyor  2 . In synchronization with continuous conveyance of sheet materials by conveyor  2 , an application gun  6  of adhesive agent application apparatus  5  reciprocates (i.e. oscillating movement) in a width direction of conveyor  2  indicated by an arrow “a” (in a direction perpendicular to a conveyance direction of the conveyor), and sprays the adhesive agent to apply the adhesive agent to an entire surface of sheet material W which is placed on the pallet provided at conveyor  2 . 
     This mechanism of adhesive agent application is also employed by the later adhesive agent application stage S 4 . At the prior adhesive agent application stage S 2 , the adhesive agent is applied to an obverse side of sheet material W. At obverse and reverse side reversal stage S 3 , sheet material W is reversed by a reversing means not shown, and then sheet material W is conveyed to the later adhesive agent application stage S 4 . At adhesive agent application stage S 4 , the adhesive agent is applied also to a reverse side of sheet material W. 
     Moreover, sheet material W whose obverse and reverse sides are applied with the adhesive agent is conveyed to sheet material take-out stage S 5  and is taken out, and then sheet material W is input into a later stage for assembling a module of lithium-ion secondary battery. 
       FIG. 3  is a diagram viewed in a direction indicated by an arrow C in  FIG. 1 , and  FIG. 4  is a plan diagram of  FIG. 3 . 
     As shown in  FIGS. 3 and 4 , sheet material stockers  3 A and  3 B are disposed on respective sides of sheet material input stage S 1 , and multiple sheet materials W are stacked in a case of each of stockers  3 A and  3 B under a condition that sheet materials W are aligned at four sides. 
     In this embodiment, both sheet material stockers  3 A and  3 B are not operated simultaneously. Under conditions that only a very few sheet materials W are left in sheet material stocker  3 A or  3 B, or sheet material stocker  3 A or  3 B is brought into an empty state by taking out all of sheet materials W, the taking-out operation is switched so as to take out sheet materials W in the other sheet material stocker  3 B or  3 A. While sheet materials W in the sheet material stocker  3 B or  3 A are being taken out, the other sheet material stocker  3 A or  3 B in the empty state is replenished with sheet materials W. 
     With regard to the sheet material stocker in operation, which is the right-side sheet material stocker  3 A in the situation of  FIG. 3 , a stocker cover  8   a  located above sheet material stocker  3 A is opened in order to allow to take out sheet materials W in sheet material stocker  3 A from above. On the other hand, with regard to the left-side sheet material stocker  3 B in the situation of  FIG. 3  which is not being operated, a stocker cover  8   b  is closed for safety measures such as replenishment operation of sheet materials W. In this way, both sheet material stockers  3 A and  3 B are not used in operation simultaneously, but are used one by one alternately. 
     Moreover, a transfer device  9  is disposed so as to extend between sheet material stockers  3 A and  3 B above sheet material input stage S 1 . Transfer device  9  is configured to allow a transfer head  11  to travel along a frame  10 , wherein transfer head  11  is a sheet material take-out means, and is provided with a plurality of vacuum pads (vacuum cups)  12  each of which is configured to move in a vertical direction. For example, in response to a condition that transfer head  11  is located just above sheet material stocker  3 A, vacuum pads  12  are moved downward to suck and support the uppermost sheet material W in sheet material stocker  3 A. In response to a condition that vacuum pads  12  are sucking and supporting the sheet material W, transfer head  11  moves vacuum pads  12  upwardly together with the sucked and supported sheet material W, and then travels to a position just above sheet material input stage S 1  on conveyer  2 . In response to a condition that transfer head  11  has traveled to the position just above sheet material input stage S 1 , transfer head  11  moves vacuum pads  12  downwardly together with the sucked and supported sheet material W, and cancel negative pressure of each vacuum pad  12 , so that sheet material W is released from vacuum pads  12 , and positioned and placed on pallet P on standby at sheet material input stage S 1 . Then, transfer head  11  travels again to the position just above sheet material stocker  3 A, and thereafter performs the above operation repeatedly. 
     As mentioned above, each of sheet material stockers  3 A and  3 B includes a case  7 , which has a rectangular shape in a planar view, wherein multiple sheet materials W are stacked in case  7  under the condition that sheet materials W are aligned at four sides therearound. The entire stacked sheet materials W are supported by a lifter table  13  which is configured to be lifted up by a motor not shown. Furthermore, lifter table  13  performs lift-up operation intermittently and controls a height position of the entire stacked sheet materials W so that the uppermost sheet material W of the stacked multiple sheet materials W is set constantly at a constant height such that the uppermost sheet material W is taken out. 
     More specifically, each of sheet material stockers  3 A and  3 B is provided with a non-contact seating sensor  14  and limit switches  15  and  16 , wherein non-contact seating sensor  14  detects the height position of the uppermost sheet material W (i.e. detects that the uppermost sheet material W is set at the height where the uppermost sheet material W is taken out), and wherein limit switches  15  and  16  manage an upward movement limit position and a downward movement limit position of lifter table  13 . These limit switches  15  and  16  are ON/OFF-operated by a dog  17  which is attached to lifter table  13 . Seating sensor  14  is implemented by a photoelectric sensor or a laser sensor. 
     Moreover, when the uppermost sheet material W is taken out by transfer head  11 , there are no object which blocks an optical axis Q of seating sensor  14 , so that lift-up operation of lifter table  13  is performed in response to OFF-operation of seating sensor  14 . When lifter table  13  and the entire stacked sheet materials W are lifted up, and the following sheet material W is brought into a position where the optical axis Q of seating sensor  14  is blocked (Le. the height where the uppermost sheet material W is taken out), lift-up operation of lifter table  13  is stopped in response to a condition that seating sensor  14  is ON-operated immediately. The intermittent lift-up operation is performed repeatedly in sheet material stocker  3 A or  3 B in synchronization with the operation of taking-out sheet material W by transfer head  11 , so that the uppermost sheet material W of the stacked sheet materials W is always positioned at the predetermined height where the uppermost sheet material W is taken out. 
     When limit switch  15  is ON-operated while the above lift-up operation is performed repeatedly, it indicates an empty condition that there are no sheet materials W on lifter table  13 , or there are only a few sheet materials W on lifter table  13 . Accordingly, in response to the condition that limit switch  15  is ON-operated, lifter table  13  is lowered at once, and stopped in a position where the other limit switch  16  is ON-operated. In this timing, the sheet material stocker where sheet materials W should be taken out is switched from sheet material stocker  3 A to sheet material stocker  3 B. Thereafter, the taking-out operation is continued for sheet materials W in sheet material stocker  3 B similar to the above operation in sheet material stocker  3 A, and replenishment operation of sheet materials W is performed by an operator for sheet material stocker  3 A in the empty condition that there are no sheet material W. 
     In this embodiment, case  7  of each sheet material stocker  3 A,  3 B is provided with gate blocks  18  and  18  which serve as a mechanism for giving curvature for preventing for double take-out of sheet materials W. As mentioned above, case  7  of each sheet material stocker  3 A,  3 B has a rectangular shape in the planar view in order to stack and store sheet materials W under the condition that sheet materials W are aligned at four sides therearound. 
     In the embodiment, as shown in  FIG. 3 , and  FIG. 5  which is a partially enlarged diagram of  FIG. 3 , wedged gate blocks  18  and  18  are disposed to face each other on respective inner wall surfaces of an upper end part of case  7  in which multiple sheet materials W are stacked, so that inner wall surfaces of the upper end part of case  7  facing two opposite sides of sheet material W gradually approaches each other as followed in an upward direction of case  7 . Each of the inner wall surfaces is implemented by an inclined surface  18   a  so that the distance between the inner wall surfaces of the upper end part of case  7  facing two opposite sides of sheet material W gradually becomes small in the upward direction of case  7 . Each gate block  18  is provided with a top plate  19  on an upper surface thereof, so that the space between top plates  19  and  19  is a minimum dimension part through which sheet materials W can be passed. 
     With sheet material stockers  3 A and  3 B configured as described above, when the uppermost one of the sheet materials W stacked in case  7  is located at the take-out height where the uppermost sheet material W is detected by seating sensor  14 , not only opposite sides of the uppermost sheet material W but also opposite sides of an uppermost group of sheet materials W including the uppermost sheet material W are necessarily in contact with inclined surfaces  18   a  and  18   a  of gate blocks  18  and  18 . 
     As mentioned above, the configuration that gate blocks  18  and  18  are disposed to face each other at the upper end part of case  7 , results in that the distance between inner wall surfaces of the upper end part of case  7  facing two opposite sides of sheet materials W is gradually reduced in the upward direction by inclined surfaces  18   a  and  18   a.    
     Therefore, the uppermost group of sheet materials W including the uppermost sheet material W are curved so as to project upward by its own elasticity, so that each sheet material W is mechanically made to have a predetermined curvature. Simultaneously, since the uppermost group of multiple sheet materials W are in contact with inclined surfaces  18   a  and  18   a , the caused curvature of the uppermost sheet material W is the largest, and the caused curvature of each sheet material in contact with inclined surfaces  18   a  and  18   a  is reduced stepwise with respect to the curvature of another sheet material immediately above the each sheet material. 
     The configuration that the sheet materials W in contact with inclined surfaces  18   a  and  18   a  are set to have curvatures projecting upward, serves to separate at least a central portion of each sheet material W from each other, and thereby ensures a space therebetween. 
     Therefore, when sheet materials W are taken out from sheet material stocker  3 A or  3 B by the suction and support of vacuum pads  12  of transfer head  11 , the sheet materials W can be reliably taken out one by one, and double take-out of sheet materials can be prevented. 
     Additionally, when attention is focused only on prevention of double take-out of sheet materials W, air may be blown from the outside to the space between sheet materials W of the uppermost group as needed, in parallel with causing the curvatures of the sheet materials W of the uppermost group in sheet material stocker  3 A,  3 B. 
     As mentioned above, at the later adhesive agent application stages S 2  and S 4 , the adhesive agent is applied to the sheet materials W which are taken out one by one from sheet material stocker  3 A or  3 B. The setting the sheet materials W to have curvatures projecting upward before sheet materials W are taken out from sheet material stocker  3 A or  3 B, is found to contribute also to improving the quality of adhesive agent application to sheet materials W. 
     More specifically, provided that the uppermost one of the stacked multiple sheet materials W is taken out sequentially, wherein sheet materials W are made of resin, each sheet material W is mutually tightly contacted with another sheet material W due to an upper load under a condition that sheet materials W are stacked, but each sheet material W has some warpage which is not uniform. Thereby, when sheet materials W are taken out one by one, and supplied to the adhesive agent application operation which is implemented by application gun  6 , dispersion occurs in the quality of adhesive agent application due to the warpage of each sheet material W. This limits the improvement and stabilization of the quality of adhesive agent application. 
     In contrast, in the present embodiment, sheet materials W are curved to have predetermined curvatures in advance, and the adhesive agent application operation to both obverse and reverse sides of sheet material W is assumed to be completed before the curvature of sheet material W is restored to an original condition due to its own restoring force. As long as the forcibly caused curvature of sheet material W remains, the warpage of sheet material W is temporarily corrected so that the curvature of sheet material W is substantially uniform and stable. 
     Accordingly, the adhesive agent application operation may be performed with setting the condition of adhesive agent application at adhesive agent application stages S 2  and S 4  shown in  FIG. 1  based on the assumption that each sheet material W has the predetermined curvature. This serves to improve and stabilize the quality of adhesive agent application to sheet materials W. 
     When the adhesive agent application operation is performed at adhesive agent application stage S 4  following the adhesive agent application stage S 2 , the sheet material W is in the reversed state as mentioned above, so that the adhesive agent application operation at adhesive agent application stage S 4  is under a condition that the curvature of sheet material W has a caused curvature projecting downward. 
     the present embodiment is described above with reference to a sheet material as an example, which is used as an insulation sheet, when multiple cells are accommodated in a metallic hard case, and modularized to form a module of a lithium-ion secondary battery, wherein each cell has a thin laminated structure. However, this is merely one example, and naturally, the present invention can be also applied to other kinds of sheet material made of resin or different material.