Abstract:
A drum configuration uses first and second rotary drums to apply alternate zipper segments in a transverse direction to a sheet of moving web or film. This allows the web to maintain a constant speed without the intermittent pausing while the zipper segments are sealed to the web.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a dual drum configuration for applying zippers in the transverse direction to a moving film or web. This is particularly applicable to the manufacture of reclosable packages or bags, such as in form-fill-and-seal (EFS) methods. 
   2. Description of the Prior Art 
   In the prior art, it is known to seal zipper segments in a transverse direction to a web or film of polymeric material. A transverse applicator including multiple wheels (or a vacuum plate) and a track plate may be used. Alternately, a single drum is used to place and seal the zipper segment to the web or film. However, in this configuration, the web or film is typically momentarily or intermittently stopped in order to seal the zipper to the web or film. This slows the production rate of the apparatus and further decreases the reliability of apparatus, as well as contributing to increased wear and vibration on the apparatus. 
   OBJECTS AND SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to increase the production rate and reliability of an apparatus for sealing of zippers in a transverse direction to a moving film or web. 
   It is therefore a still further object of the present invention to provide for sealing of zippers in a transverse direction to a moving film or web while maintaining a continuous motion of the film or web. 
   These and other objects are attained by providing a dual rotary drum configuration, wherein the rotary drums are spaced apart from each other in the machine direction of the moving web or film. Zipper segments are fed into the rotary drums and the rotary drums rotate into position for sealing the zipper segments in a transverse configuration to the moving film or web. The rotary drums are programmed so as to be synchronized whereby the first rotary drum rotates with a matched speed of the film or web during sealing while the second rotary drum is receiving and positioning the next zipper to be sealed. 

   
     DESCRIPTION OF THE DRAWINGS 
     Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein: 
       FIG. 1  is a side plan view of the rotary drum configuration of the present invention, further showing the moving film or web and transverse zipper segments. 
       FIG. 2  is a top plan view of the rotary drum configuration of the present invention, further showing the moving film or web and transverse zipper segments. 
       FIG. 3  is a top plan view of the resultant web configuration after full width drums are used to apply double zipper segments. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings in detail wherein like numerals indicate like elements throughout the several views, one sees that  FIG. 1  is a side plan view of the rotary drum configuration  10  of the present invention, while  FIG. 2  is a top plan view thereof. Rotary drum configuration  10  includes first rotary drum  12  and second rotary drum  14 . Rotary drums  12 ,  14  rotate in the clockwise direction (in the configuration and orientation of  FIG. 1 ) in synchronization with web  100  which moves to the left. 
   First and second rotary drums  12 ,  14  include respective first and second longitudinal zipper notches  16 ,  18  which receive respective zipper segments  102 ,  104  from respective first and second zipper sources  20 ,  22 . First and second zipper sources  20 ,  22  typically cut the zipper segments from continuous lengths of zipper material prior to loading and may include a slider mounting device (not shown). The zipper segments  102 ,  104  (with respective optional mounted sliders  103 ,  105  which operate to separate the profiles of the zipper segment when moved in a first direction and interlock the profiles of the zipper segment when moved in a second direction) are received when the respective zipper notches  16 ,  18  are at the uppermost position (see first rotary drum  12 ). The rotary drums  12 ,  14  then rotate to position the zipper segments  102 ,  104  against web  100  and seal the zipper segments  102 ,  104  thereto. This can be accomplished with the web  100  moving at a constant speed and the periphery of first and second rotary drums  102 ,  104  moving at a constant rotational speed (as measured in distance per unit time rather than radians per unit time) or circumferential speed equal to the constant speed of the web at least during the sealing process but possibly throughout the entire rotation (with an intermittent pause in the rotation to allow the loading of the zipper segment in the rotation position illustrated by second rotary drum  12  in  FIG. 1 ). Zipper segments  102  (placed by first rotary drum  12 ) and zipper segments  104  (placed by second rotary drum  14 ) alternate with each other along the length of web  100 . CPU  200  includes programming (along with necessary memory, storage and information input, such as speed of the web  100 ) to synchronize the rotation, timing and functions of first and second rotary drums  12 ,  14 , first and second zipper sources  20 ,  22 , and associated functions in order to provide the desired (typically constant distance) spacing between the successive zipper segments. Web  100  with the zipper segments  102 ,  104  sealed thereto is provided to subsequent manufacturing steps for a reclosable package or bag, typically a form-fill-and-seal process. 
   First and second rotary drums  12 ,  14  are illustrated as being one half the width of the web  100  and centrally located thereon. However, the first and second rotary drums  12 ,  14  could be the entire width of the web  100  with the zipper segments  102 ,  104  centrally located therein. 
   As it is envisioned that first and second rotary drums  12 ,  14  have a periphery which has a circumferential rotational speed substantially equal to the linear speed of the web  100 , it can be seen that rotary drums  12 ,  14  are illustrated with an enlarged circumference with respect to the spacing of the zipper segments  102 ,  104  on web  100  (that is, in the case of constant rotational speed equal to the linear speed of the web, the distance between a zipper segment  102  and the immediately adjacent zipper segment  104  as measured in the machine direction will be one half of the circumference of the rotary drums  12 ,  14 ). Additionally, while zipper notches  16 ,  18  are illustrated at respective uppermost and lowermost rotational positions, there is likely to be some further phase shift introduced in order to compensate for the machine direction distance between the rotational axes of first and second rotary drums  12 ,  14 . Similarly, the illustrated embodiment of rotary drum configuration  10  includes zipper segments  102 ,  104  which are substantially one half the width of the web  100 . It is envisioned that the lateral edges of web  100  would eventually brought together and sealed over the zipper segments to form the second wall of a reclosable package or bag (not shown). However, of course, rotary drum configuration  10  is equally applicable to other proportions of zipper segment length to web width (such as, but not limited to, providing zipper segments across the entire width of the web, with the second wall of the subsequent reclosable package being supplied by a separate source of web of equal width thereby providing the possibility of using double zipper segments  102 ′,  104 ′ for subsequent production of two packages or bags at a time as shown in  FIG. 3 ). 
   An alternative use for the disclosed rotary drum configuration  10  is to load different types of zipper into first and second zipper sources  20 ,  22  in order to use only one of the first and second zipper sources  20 ,  22  for a given production run and allow a quick conversion or change-over between the two. 
   Thus the several aforementioned objects and advantages are most effectively attained. Although preferred embodiments of the invention have been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.