Abstract:
A method of converting at least one strip of flexible material  12  into at least one stack of folded members  46.  The method includes the step of conveying a number of festoons  20  formed from a strip of flexible material  12.  The method is characterized by the step of depositing the respective festoons  20  into a stack of folded members  46.  In the preferred method, the step of depositing the respective festoons  20  into a stack of folded members  46  can be characterized further by the steps of: (i) laying an initial flap  36  of flexible material  12  on a stacking surface  24;  (ii) creating a first folded member  44  by placing a first festoon  42  on the initial flap  36  of flexible material  12;  and (iii) creating additional folded members by placing each festoon upon a preceding festoon.

Description:
TECHNICAL FIELD 
     This invention relates to a method of converting a strip of flexible material into a stack of folded members and, more particularly, to a stack having at least one side where all of the folded members are aligned. 
     BACKGROUND ART 
     The need to convert a strip of flexible material into a stack of folded members arises in many industries, such as the textile and rubber industries. In the rubber industry, one such need arises when processed rubber is to be used in injection molding machines. A method of processing rubber, either synthetic or natural, begins by dumping the necessary raw materials into the hopper of a Banbury. After the raw materials are properly mixed, the resulting rubber is conveyed to a screw feeder which further mixes the rubber and conveys it to a calender. The calender includes a pair of rollers that transform the screw fed rubber into a wide strip of rubber. Generally, this wide strip of rubber has a width of between thirty inches (76.2 cm) and thirty-six inches (91.44 cm). If this rubber is to be used in an injection molding machine, it must be cut into narrow strips. Injection molding machines typically will only accept rubber strips with a width of six inches (15.24 cm) or less. To load these strips into an injection molding machine, an operator feeds an end of a narrow rubber strip into an inlet of the injection molding machine. After accepting the end of the narrow strip of rubber, the injection molding machine automatically draws the strip into the inlet as needed. 
     To efficiently produce injection molded rubber products, rubber manufacturers need an efficient way to produce these narrow strips of rubber and to transport these strips of rubber to the location of the injection molding machines. Since most manufacturing plants are already equipped to move palletieed products, the easiest way to sport a product from one location to another is to stack the product and transport it on a pallet. 
     If the product is to be transported by pallet, a rubber manufacturer can either cut the wide strip of rubber into narrow strips prior to palletizing, or they can palletize the wide strip and then cut it into narrow strips. Whichever method is used to reduce the width of the rubber strips, there is a need to neatly stack the rubber. If the rubber is cut into narrow strips prior to stacking, the stacks must be neat to assure that a first narrow strip is not overlapped by a second narrow strip. If the second narrow strip overlaps the first narrow strip, the first narrow strip will likely break when being drawn into the injection molding machine. The overlap of the second narrow strip applies a tension to the first narrow strip of flexible material causing it to stretch and break if the first narrow strip breaks, the remaining end of the strip must be manually fed into the inlet of the injection molding machine. If the wide strip of rubber is stacked prior to being cut, the stacks must be neat to assure that when cut, the narrow strips will have a relatively uniform width. If the rubber is sloppily stacked, cutting the stack at various points will result in narrow strips with their widths varying along their length. A single strip could have a width of one inch at one point and a width of ten inches at another point. As a result, the narrow strip may easily break when being drawn into the injection molding machine or the strip may be too wide to properly fit into the inlet of the injection molding machine. In either case, manual labor may be required to either feed the remaining end of the narrow strip into the injection molding machine or to trim the narrow strip down to a size that the injection molding machine can utilize. 
     Currently, after exiting the calender, the wide strip of rubber is either placed on a festoon type conveyor or cut into narrow strips, and the narrow strips placed on the festoon type conveyor. On the festoon conveyor, each strip is hung over a series of bars and allowed to suspend loosely between the bars. The festoon conveyor carries the respective strip or strips of rubber through a cooling chamber where the rubber is cooled. After leaving the cooling chamber on the festoon conveyor, a belt conveyor removes the respective strip or strips from the festoon conveyor. The belt conveyor moves the respective strip or strips to a wigwag device for stacking. 
     The wigwag device is a simple mechanical device having a surface that moves back and forth at a constant speed to stack a respective strip into folded members. The stack created by the wigwag device is very messy. This is especially true when the wigwag is attempting to stack multiple narrow strips at one time because the narrow strips can easily overlap one another. Additionally, the wigwag device does not assure that each folded member of a respective strip is flatly placed on top of the previous folded member of that strip. When the respective folded members are not lying flatly, there is a greater likelihood that overlapping of the respective strips will result. 
     U.S. Pat. No. 3,032,337 entitled “CONTINUOUS STACKING SYSTEM” discloses a system to stack a continuous ribbon of material. This system positions a belt conveyor directly above the slab where the ribbon is to be stacked. An oscillating wall is used to help lay down the first portion of the ribbon and the remaining portions of the ribbon are placed by the side to side motion of the ribbon that results from the oscillating wall laying down the first ribbon. 
     SUMMARY OF THE INVENTION 
     This invention discloses a method of converting at least one strip of flexible material into at least one stack of folded members. The method includes the step of conveying a number of festoons formed from a strip of flexible material. The method is characterized by the step of depositing the respective festoons into a stack of folded members. 
     The step of depositing the respective festoons into a stack of folded members can be characterized further by the steps of: (i) laying an initial flap of flexible material on a stacking surface; (ii) creating a first folded member by placing a first festoon on the initial flap of flexible material; and creating additional folded members by placing each festoon upon a preceding festoon. 
     The method of this invention results in a stack having at least one side where the folded members are aligned. A further aspect of this invention provides additional steps that can be utilized to align additional sides of the stack. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     The invention will be described by way of example and with reference to the accompanying drawings in which: 
     FIG. 1 is a view of an apparatus that may be used to perform the preferred method of the invention; 
     FIG. 2 is a view of the stacking surface contacting an initial flap of flexible material and moving to cause the initial flap to lie flatly on its surface; 
     FIG. 3 is a view showing a movement of the stacking surface such that the bars being removed from the stack move in a direction horizontal, relative to the stacking surface; 
     FIG. 4 is a view of the stacking surface at its low point and the conveyor moving upward such that the bars, being removed from the stack, move in a direction horizontal, relative to the stacking surface; 
     FIG. 5 is a view of a first stack of folded members under a new stack; 
     FIG. 6 is a view of the new stack of folded members on the stacking surface, and of the conveyor and stacking surface moving downward to a reset position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows an apparatus  10  for performing the preferred method of the invention. As shown, at least one strip of flexible material  12  has been placed on a festoon type conveyor  14 . The festoon type conveyor  14  consists of a series of parallel bars  16 , or other like supports, that are held between two drive chains  18 . The drive chains  18  are driven by at least one motor driven pulley. When placed on the conveyor  14 , the flexible material  12  is allowed to suspend loosely between the respective bars  16  to form a number of festoons  20 . The respective bars  16  of the conveyor  14  that provide support for the festoons  20  of flexible material  12  are referred to as material supporting bars. 
     After being placed on the conveyor  14 , the festoons  20  are conveyed along a path of the conveyor  14  such that the orientation of the festoons  20  is maintained. The orientation of the respective festoons  20  is changed as the respective material supporting bars  16  travel around a pulley  22  and begins to move in a downward direction toward a stacking surface  24 . As the respective bars  16  pass around the perimeter of the pulley  22 , the material supporting bar  16  for a leading surface  26  of each festoon  20  travels to a position below the material supporting bar  16  for a trailing surface  28  of that respective festoon  20 . As a result, the leading surface  26  of each festoon  20  lies on either the trailing surface  28  of a preceding festoon or, where there is no preceding festoon, on a preceding bar  32  on the conveyor  14 . A preceding festoon is a festoon on the conveyor immediately preceding the festoon at issue. This change in orientation of the respective festoons  20  may be aided by the use of a deflection surface  34 . The deflection surface  34  may be used to help separate the respective festoons  20  when the orientation is changed, especially when the flexible material  12  has an adhesive characteristic. The use of the deflection surface  34  will allow freer movement of each festoon  20 . 
     As seen in FIG. 2, after the orientation of the respective festoons  20  has been changed, a movable stacking surface  24  is used to contact an initial flap  36  of the flexible material  12 . The initial flap  36  of flexible material  12  is located between a leading edge  38  of the flexible material  12  and the first material supporting bar  40 . The first material supporting bar  40  supports the initial flap  36  of flexible material  12 . After the change in orientation, the initial flap  36  of the flexible material  12  will be lying against the preceding bar  32  on the conveyor  14 . The preceding bar  32  is the bar  16  not supporting any flexible material  12 , immediately preceding the first material supporting bar  40 . The movable stacking surface  24  is inserted into an area between the first material supporting bar  40  and the proceeding bar  32 . The stacking surface  24  moves with the proceeding bar  32  until making contact with the initial flap  36  and causing the initial flap  36  to lie flatly upon its surface. When the stacking surface  24  is being inserted, either the conveyor  14  or the stacking surface  24  moves such that the first material supporting bar  40  moves in a horizontal direction relative to the stacking surface  24 . As the first material supporting bar  40  is moved in a horizontal direction relative to the stacking surface  24 , it is removed from the stack of flexible material  12 . After complete removal from the stack, the first material supporting bar  40  no longer needs to be moved in a direction horizontal to the stacking surface  24  and may be moved in any direction. 
     After changing the orientation of the festoons  20 , a first festoon  42  has a leading surface  26  that is lying on the initial flap  36  of flexible material  12 . As the initial flap  36  is caused to lie flatly upon the stacking surface  24 , the first festoon  42  moves with the initial flap  36  into a position above the initial flap  36  on the stacking surface  24 . The respective material supporting bars place this first festoon  42  on the initial flap  36  of flexible material  12 , creating a first folded member  44 . The leading surface  26  of the first festoon  42  lies directly on top of the initial flap  36  and the trailing surface  28  of the first festoon  42  continues to support the next festoon. As seen in FIG. 3, in the preferred method, the stacking surface  24  moves down such that the respective material supporting bar is moved in a horizontal direction with respect to the stacking surface  24  and is removed from the respective folded member  46 . Each festoon is placed on the preceding festoon to create additional folded members  46 . Instead of moving the stacking surface  24  down, the conveyor  14  may be moved upward, as long as the movement of the respective material supporting bars, after laying down their respective festoons  20 , is in a horizontal direction relative the stacking surface  24 . It is preferred that the stacking surface  24  move down with respect to the conveyor  14  until it has reached a low point, as depicted in FIG.  4 . After the stacking surface  24  has reached the low point, the conveyor  14  will begin to move upward. This increases the number of folded members  46  that can be placed on the stacking surface  24  prior to removal of the stack. 
     Since the material supporting bars of the conveyor  14  are moved in a horizontal direction relative to the stacking surface  24  when being removed from the stack, the material supporting bars can be used to flatten each folded member and to aid in placing the next folded member. By keeping a respective material supporting bar in contact with the respective folded member as it is being removed, the respective material supporting bar can be dragged or rolled across the respective folded member to flatten it. Additionally, as each material supporting bar is being removed, it supports at least a portion of the leading surface  26  of the next festoon. As a result, the respective material supporting bar can be used to control the placement of the next festoon onto the stack. To aid in these processes, each bar  16  of the conveyor  14  may be a movable roller or have other similar features. 
     Since placement of the stack of folded members  46  is controlled by the respective material supporting bars, a stack created by this method will have at least one side where all the folded members  46  are aligned. At least the side of the stack of folded members  46  where the respective material supporting bars first place the festoons  20  will be aligned. A stack having all sides aligned, or straight, may be created by this method by suspending a predetermined amount of the flexible material  12  between the respective material supporting bars and by accurately placing the flexible material  12  in the same area of each material supporting bar on the conveyor  14 . 
     Depending upon the length of the strip of flexible material  12 , more than one stack of folded members  46  may be necessary. If more than one stack is necessary, the first stack  48  may be removed and a new stack  50  stated without stopping the conveyor  14 . As seen in FIG. 5, when the first stack  48  of folded members  46  reaches a predetermined height, a new stacking surface  52  is inserted into the area between two of the respective material supporting bars to support the flexible material  12 . The flexible material  12  is cut at the location of the new stacking surface  52 . The flexible material  12  below the new stacking surface  52  is placed upon the first stack  48  and the remaining portion of flexible material  12  is stacked upon the new stacking surface  52 . After all the flexible material  12  has been placed on the first stack  48 , the first stack  48  is quickly removed from the area direty under the new stacking surface  52 . As the new stack  50  grows, either the new stacking surface  52  can be moved down, away from the conveyor  14  or, as shown in FIG. 6, both the conveyor  14  and the stacking surface  24  can be moved down to a reset position similar to that depicted in FIG.  3 . 
     The method of this invention converts at least one strip of flexible material  12  into at least one stack of folded members  46 . The method results in a neater stack of folded members  46 , having at least one side where all of the folded members  46  are aligned. If the flexible material  12  is neatly stacked, the narrow strips formed from the stacked material will be more uniform and will not be overlapped by other strips. As a result, the amount of manual labor needed to feed these strips into an injection molding machine is reduced. Additionally, the method eliminates the need for a belt conveyor and a wigwag device currently used to stack a respective strip of flexible material  12  so capital costs and floor space will be saved.