Patent Publication Number: US-7901535-B2

Title: Apparatus and method for making cellular shade material

Description:
TECHNICAL FIELD OF THE INVENTION 
     This invention relates to an improved apparatus and a method for making a cellular shade material. 
     BACKGROUND OF THE INVENTION 
     One well-known type of window treatment is the honeycomb window shade. In a honeycomb window shade is made up of an interconnected series of rows of cells of a thin foldable material suspended from a headrail. There are a variety of apparatus and methods known in the art for manufacturing such honeycomb shades. One technique, disclosed in U.S. Pat. No. 4,450,027 to Colson, involves folding a continuous strip of fabric into a tube, applying adhesive to the exterior of the tube and then winding the tube onto a rotating rack so that the adjacent windings of the stacked tube are bonded together to form a honeycomb array or stack of cells. The stacked array of cells is then cut and the cellular structure removed from the tube. U.S. Pat. No. 5,228,936 and U.S. Pat. No. 5,714,034 to Goodhue is directed to another apparatus and method for making a cellular structure. In these patents, a continuous process of folding a strip of material to form a tubular structure, applying adhesive to the tubular structure, cutting the strip including adhesive and stacking the cut strips to form a cellular structure is disclosed. One disadvantage with such a process and apparatus is that since the adhesive is applied to the strip of material before cutting, the process requires the further step of chilling or heating the material after the adhesive has been applied to dry or cure the adhesive. This is done so as to reduce the amount of adhesive residue on components located downstream in the process, such as the cutter and feed rollers. 
     The number of columns of cells in the honeycomb structure may also be varied in their construction by adjusting the folding pattern of the material. For example, U.S. Pat. No. 5,834,090 to Huang discloses a process in which individual strips of material are folded and attached together with an adhesive to create a cellular structure having multiple columns of cells by folding the strip into a variety of configurations before adhesively attaching the sheets together. One problem with this process is that a web is provided, which is folded and stacked, and therefore, different width webs must be utilized for different width window coverings. 
     The present invention is an improvement on the described devices and processes for making such honeycomb structures which offers several advantages over the existing art that will be evident to those skilled in the art. Some of these advantages are provided below. 
     SUMMARY OF THE INVENTION 
     A method and apparatus for making an expandable honeycomb structure suitable for a window covering is provided. A continuous ribbon or strip of material, which is typically provided in the form of a roll, is provided by a series of feed rollers in operative communication with a drive mechanism downstream to a folder. The folder folds the continuous ribbon as it is conveyed therethrough to form a preform from the ribbon of material. The preform can be folded in a manner that will create one or more tubes defined by the single strip of material. Alternatively, the preform can be folded in a way that the strip, when adhered to other similarly formed strips, forms the cells of the honeycomb panel. The preform includes portions which are folded to overlap with other portions, such as a marginal portion folded over a main portion, such as a central portion. The preform can also be prefabricated such that it is provided to the cutter from a pre-made supply. In other words, the formation of the preform does not need to be completed in a continuous process with the other fabricating steps. 
     The form of the rows that are eventually constructed may be varied by the folding pattern utilized. This may include single cell or double cell honeycombs, or symmetrical or asymmetrical shaped rows. The preforms may also form partial cells, which when adhered to similarly formed preforms form complete cells. The preform is then conveyed downstream by other feed rollers, which may be also operatively connected to the drive, past a cutter. The operation of the cutter is synchronized with the feeding of the preform such that a desired length of the preform may be transported past the cutter without being cut. When a desired length of the preform is conveyed past the cutter, the cutter severs at least a portion of the preform in a direction perpendicular to the machine direction to define a row member. 
     An adhesive applicator positioned downstream of the cutter applies at least one line of adhesive to the material after it passes the cutter. The portion of the material cut by the cutter does not include adhesive since the adhesive is applied downstream of the cutter. After the adhesive is applied and the preform is severed by the cutter to form the row member, the row member is transported to a stacker. The stacker bonds the row member with other similarly formed row members by stacking it therewith. The stacking is completed before another row member is conveyed into the stacker. References to downstream and upstream denote movement of materials through the process or positioning of equipment. In particular, moving downstream means moving towards the stacker, and being positioned downstream means being positioned closer to the stacker. 
     In some embodiments, the rate of progress of the row member into the stacker is increased. This can be accomplished through the use of a variety of components, however, it is preferred that an air flow device, such as a vacuum or a blower be used to urge the row member into the stacker. 
     One advantage of this embodiment over the methods and apparatus of the prior art such as disclosed above is a result of the positioning of the adhesive applicator. The prior art discloses the application of adhesive upstream of the cutter, and requires the additional step of cooling or heating the adhesive to dry or cure the adhesive so that adhesive residue on the cutter is reduced. Such an additional step is not required with the present invention. This is because the cutter is positioned upstream of the adhesive applicator. Accordingly, the process is more efficient since these additional curing steps are not required. For example, since the adhesive has not been cured, no additional heating or curing step is required to bond the row member to other row members in the stack. The present invention also requires less downtime to clean or replace cutter and roller components befouled with adhesive residue. 
     An optional feature of the present method and apparatus is the partial cutting of the preform. In other words, rather than completely sever the preform when forming the row member, the preform may instead be perforated such that a frangible material strip of material is created. The row member can then be fully separated by accelerating the row member relative to the remainder of the material strip. 
     While the present invention has been discussed thus far as only including a single adhesive application step, other variants are possible. For example, the process may include in the formation of the preform an additional step of applying adhesive to the ribbon of material, folding of the material, and adhering portions of the material to itself. This prefabricated preform can be supplied in the form of a roll. The cutter and rollers still would not endure the problem of unwanted adhesive residue since the adhesive already secures the material to itself and is preferably cured. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, 
         FIG. 1  is a schematic side view of one form of an apparatus for performing a method according to the present invention; 
         FIG. 2  is a cross-sectional view along the line  2 - 2  of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view along the line  3 - 3  of  FIG. 1 ; 
         FIG. 4  is a cross-sectional view of a tubular preform; 
         FIG. 5  is a cross-sectional view along the line  5 - 5  of  FIG. 1 ; 
         FIG. 6  is a cross-sectional view along the line  6 - 6  of  FIG. 1 ; 
         FIG. 7  is a perspective view of a window covering including the cellular structure formed according to the method of  FIG. 1 ; 
         FIG. 8  is a schematic side view of an alternative form of an apparatus for performing a method according to the present invention; 
         FIG. 9  is a cross-sectional view along the line  9 - 9  of  FIG. 8 ; 
         FIG. 10  is a cross-sectional view along the line  10 - 10  of  FIG. 8 ; 
         FIG. 11  is a cross-sectional view of a tubular preform; 
         FIG. 12  is a cross-sectional view along the line  12 - 12  of  FIG. 8 , 
         FIG. 13  is a cross-sectional view along the line  13 - 13  of  FIG. 8 ; 
         FIG. 14  is a perspective view of a window covering including the cellular structure formed according to the method of  FIG. 8 ; 
         FIG. 15  is a schematic cross-sectional view of an alternative preform folding pattern for the material; 
         FIG. 15A  is a foreshortened schematic cross-sectional view of the preform of  FIG. 15  stacked with other similarly constructed preforms; 
         FIG. 16  is a schematic side view of another alternative embodiment of an apparatus for performing a method according to the present invention; 
         FIG. 17  is a schematic cross-sectional view of a preform from  FIG. 16 ; and 
         FIG. 18  is a schematic cross-sectional view of an alternative preform from  FIG. 16 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION 
     The invention disclosed herein is susceptible of embodiment in many different forms. Shown in the drawings and described hereinbelow in detail are preferred embodiments of the invention. It is to be understood, however, that the present disclosure is an exemplification of the principles of the invention and does not limit the invention to the illustrated embodiments. 
       FIGS. 1-6  illustrate a preferred embodiment of the method and apparatus according to the present invention. A continuous ribbon or strip of material  10  is typically provided in the form of a roll  12 . A drive mechanism operatively connected to a series of feed rollers  16 , shown schematically as box  14 , continuously pulls the material  10  off of the roll  12  and conveys the material  10  downstream to a folder  18 . The material  10  is folded by the progression of the material  10  through the folder  18  to form a preform. For example, as shown in  FIGS. 2 and 3 , the material  10  is folded as it passes through channel  22  of folder  18 . Other methods of folding will be recognized by those skilled in the art. In  FIG. 2 , the material is folded such that two opposed marginal portions  24  and a central portion  26  are formed. Referring to  FIG. 3 , the two marginal portions  24  are folded over the central portion  26  to form a tubular preform  28 . After folding, the preform  28  includes two marginal portions  24  on top of the central portion  26  as shown in  FIG. 4 . Another series of feed rollers  29  which are also preferably operatively connected to drive  14 , continues feeding the material  10 , and in particular preform  28  downstream to a cutter  30 . In this embodiment, the cutter is represented by one rotating drum or cutter  32  carrying a cutting blade  34  and a second rotating drum  36 . The preform  28  is guided past cutter  30 . The drums  32  and  36  rotate at a speed synchronized to the feeding rate of the preform  28  such that desired lengths of the material are cut, as is known in the art. As the blade  34  rotates and contacts the preform  28 , the blade  34  severs the preform, thereby defining a row member  38 . 
     Positioned downstream of the cutter  30  is an adhesive applicator  40  that applies at least one line of adhesive to the material that has passed downstream of the cutter  30 . In this particular embodiment, a pair of lines of adhesive  42  are deposited as shown in  FIG. 5 . The adhesive lines are positioned at the edges of the marginal portions  24 . 
     The row member  38  with adhesive lines  42  is supported by a conveyor belt  44  and is transported downstream to stacker  46 . As the row member  38  approaches stacker  46 , an airflow device, such as a vacuum  48 , accelerates the downstream conveyance of the row member  38  into the stacker  46 . Referring to  FIG. 6 , the row member  38  is supported within the stacker on lift member  50 , which raises the row member  38  into contact with other similarly formed row members  52  and bonds row member  38  thereto. A detailed explanation of a preferred embodiment of the stacking device  46  is provided in U.S. Pat. No. 5,630,900, which is incorporated herein by reference. Unlike the prior art method and apparatus of U.S. Pat. No. 5,228,936 and U.S. Pat. No. 5,714,034 to Goodhue, there is no need to apply additional pressure and heat to activate the adhesive lines to cause the row members to adhere to one another because the adhesive in the present embodiment of the invention is not dried or cured as required in the prior art. Also, since the adhesive is applied downstream of the cutter, adhesive residue on the cutter  30  and feed rollers  29  is prevented. 
     After forming the cellular structure, appropriate control cords and control mechanisms, which are typically found in a head rail, are attached to the cellular structure. A window covering  54  including the cellular structure  56  made according to the method described above is shown in  FIG. 7 . As shown, the cellular structure  56 , when expanded forms a single column of cells having a symmetrical face  58  and rear  60 . 
     It should be recognized that the particular material of the strips and the adhesive utilized are not critical aspects of the invention. Any materials commonly utilized in the art of cellular structures suitable for window coverings may be used. For example, the material for the rows may be fabric, paper, film, or the like. 
     Another embodiment of the present invention is shown in  FIGS. 8-14 . The apparatus and process depicted is similar to the previous embodiment. Referring to  FIG. 8 , a continuous ribbon of material  110  on roll  112  is conveyed by drive  114  and a series of rollers  116  downstream to a folder  118 . The material  110  is again folded by the progression of the material  110  through the folder  118  to form a preform. In this embodiment, the folder  118  is configured to create a somewhat different preform than in the previous embodiment. As shown in  FIGS. 9 and 10 , the material  110  is folded as it passes through channel  122  of folder  118 . The material is folded such that two marginal portions  124  and  125  and a central portion  126  are formed. Marginal portion  124  is wider than marginal portion  125  such that the preform  128  has an asymmetrical transverse cross section as shown in  FIG. 11 . The preform  128  again continues downstream to a cutter  130  and adhesive is applied in a similar fashion to that described above by applicator  140 . Since the folding pattern of the present embodiment is somewhat different, the adhesive lines  142  are set down as shown in  FIG. 12 . 
     As with the previous embodiment, the row member  138  is transported downstream by conveyor belt  144  supporting the row member to stacker  146 . As the row member  138  approaches stacker  146 , an airflow device, such as blower  148  accelerates the downstream conveyance of the row member  138  into the stacker  146 . Alternatively, although not shown, a set of rollers having a greater surface speed than the speed of the conveyor  144  can also be used to accelerate the row member  138 . Preferably, such a set of rollers would be split rollers to avoid contact with the adhesive lines. Referring to  FIG. 13 , the row member  138  is supported within the stacker on lift member  150 , which raises the row member  138  into contact with other row members  152  and bonds row member  138  thereto. A window covering  154  including the cellular structure  156  formed as described is shown in  FIG. 14 . As shown, when expanded, the cellular structure  156  forms a single column of cells, each cell having a pleated face  158  and a substantially flat rear  160 . The rear  160  also acts as a limiting member which restricts the amount the cells and overall window covering may be expanded. 
     With each of the previous embodiments, a preform that forms a complete tube is described. Other folding patterns may also be utilized. For example, referring to  FIG. 15 , a non-tubular folding pattern is shown. Preform  180  is formed from marginal portions  182  and  184 , which are overlapped with central portion  186 . Adhesive lines  188  and  190  are placed by the adhesive applicator. When stacked, the preform  180  cooperates with similarly constructed preforms to form a cellular structure  192  such as shown in  FIG. 15A . 
     Another embodiment of a process and apparatus according to the present invention, is shown in  FIGS. 16-18 . In many respects, this embodiment is like that shown in  FIGS. 1-6 . 
     Referring to  FIG. 16 , as before, a continuous ribbon of material  210  is conveyed by a drive mechanism (not shown) from a roll  212  by way of a series of feed rollers  216  downstream to a folder  218 . The material  210  is folded to form a preform, which is conveyed by another series of feed rollers  229  to a cutter  230 . As in the previous embodiments, positioned downstream of the cutter  230  is an adhesive applicator  240  that applies at least one line of adhesive to the material that has passed downstream of the cutter  230 . The row member is transported downstream to stacker  246  by conveyor belt  244 , and as the row member approaches stacker  246 , an airflow device, such as a vacuum  248 , accelerates the downstream conveyance of the row member  238  into the stacker  246 , which stacks the row member with similarly formed row members. 
     In this alternative embodiment, an additional adhesive applicator  270  is also provided. Adhesive applicator  270  places at least one line of adhesive on the material  210  before it enters the folder  218 . For example, as shown in  FIG. 17 , adhesive lines  272  are placed on a central portion  274 . Marginal portions  276  and  278  are folded over central portion  274  and adhered thereto by adhesive lines  272  to form this alternative preform. The preform then, as discussed above, is transported downstream to a cutter  230 , and then adhesive applicator  240  places adhesive lines, such as lines  280  and  282 . Because the adhesive lines  272  are used to adhere marginal portions  276  and  278  to central portion  274  before the material is cut, the cutter  230  and feed rollers  229  do not contact free adhesive. Another example of such a folding pattern is shown in  FIG. 18 . In this example marginal portion  284  and marginal portion  286  are folded over opposite surfaces of central portion  288 . Only adhesive line  290  is applied by adhesive applicator  270 . Adhesive lines  292  and  294  are applied by applicator  240 . With each of these folding patterns, double cell rows are formed when stacked. 
     In the embodiments discussed, the conveyance of the material from the supply roll downstream to the cutter and to the stacker is a continuous process. One alternative is to convey material to the cutter in an intermittent or stop-and-go manner. For example, referring again to  FIG. 1 , the drive  14  may be operated such that after the cutter severs the material  10  to form a row member, the feeding of material to the cutter is halted. The row member continues to the stacker  46  for further processing as discussed. After the row member is stacked, the drive  14  resumes feeding material for processing. With such a configuration, it is preferred that the cutter, rather than being a rotating drum  32 , is a guillotine-type cutter. 
     It is also contemplated that rather than supply a strip of material to a folder, a prefolded supply of material may be utilized. In other words, material can be formed into the preform in a separate procedure, or on a separate apparatus. This prefolded supply of preform material may then be processed through the cutting, application of adhesive, and stacking operations in any of the manners discussed above. 
     The foregoing descriptions are to be taken as illustrative, but not limiting. Still other variants within the spirit and scope of the present invention will readily present themselves to those skilled in the art.