Abstract:
A process for producing partitioned packages by which a first film is formed into an elongated inner tube and a second film is formed into an elongated outer tube surrounding the inner tube. Reactive components are filled into the inner and outer tubes as the tubes are formed to maintain the reactive components separate from each other. Only the outer tube is actively engaged to advance the tube longitudinally. Frictional forces from the advancing outer tube are applied to the component within the outer tube and, in turn, are applied to the inner tube thereby advancing the inner tube at a rate substantially the same as the outer tube.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application No. 60/693,576, entitled “Device for Forming Partitioned Film Packages”, filed Jun. 24, 2005, and herein incorporated by reference in its entirety. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention is directed to a process for producing tubular film packages having a partition to maintain different materials on either side of the partition. More particularly, the present invention is directed to a method of producing mine roof bolt resin packages in which a polymerizable resin component an a catalyst are temporarily maintained on opposing sides of a partition in a tubular package. 
   2. Description of Related Art 
   Mine roof bolts and other structural elements are often anchored into rock, concrete or the like by a combination of adhesives and mechanical structures such as an expansion anchor at the distal end of the bolt. Adhesives are generally formed in place within the borehole by providing a resin cartridge that is a dual compartment package containing a polymerizable resin in one compartment and a hardener or catalyst in another compartment. A borehole is drilled in the rock and the cartridge containing the polymerizable resin and catalyst is inserted into the blind end of the borehole. When a mine roof bolt is inserted into the borehole, the distal end of the bolt ruptures the package so that the resin and catalyst are mixed. Typically, the bolt is rotated to enhance mixing until the resin hardens to a degree that the bolt can no longer be rotated and the resin is allowed to cure. 
   In these two component packages, it is critical that the polymerizable resin and the catalyst are maintained separate from each other until the package is ruptured during installation of the mine roof bolt. Some resin cartridges include an inner compartment containing catalyst surrounded by an outer compartment containing the polymerizable resin. Other resin cartridges employ a barrier to divide a container into two compartments with the catalyst and resin on opposing sides of the barrier. In an aggressive environment such as an underground mine, resin cartridges are often produced from strong films such as polyethylene terephthalate, such as Mylar®. Polyethylene terephthalate provides the desired structural integrity to the resin cartridge, yet is more costly than other pliable films that may be used in less aggressive environments. Conventional resin cartridges often use polyethylene terephthalate for the outer compartment as well as the inner compartment of the barrier, even though these inner structures are not exposed to the underground mine environment and do not require the structural integrity of the outer compartment. 
   Resin cartridges are produced via various techniques. For example, a resin cartridge having an interior barrier for separating the reactive components can be produced by forming a web of film into an advancing tube with the edges of the tube overlapping each other to produce a tube with an inner web spanning the diameter of the tube. The web is sealed to the tube thereby creating two adjacent compartments with the web being common to both compartments as a barrier. Resin cartridges with a barrier layer that spans a tube have also been produced by forming an advancing tube using a cylindrical forming member. As the tube advances, a strip of film material is advanced through the tube and heat sealed to opposing sides of the tube. However, the heat seals between the barrier and the tubing present an opportunity for failure of the resin cartridge and premature mixing of the polymerizable resin and catalyst. 
   Alternatively, two compartment packages can be formed by drawing a web of film into a cylindrical forming member to bring the web&#39;s edges together in an overlapping relationship and advancing the resulting first tube past the forming member. A second web of pliable film is fed through another forming member to produce a second tube that advances within the advancing first tube at a rate substantially equal to the rate of advancing of the first tube. The first tube is advanced by pinching the edges of the first tube between two pairs of opposing rollers, and the second tube is advanced by similarly pinching the edges of the second tube between two pairs of opposing rollers. This process requires that the advancing rollers for the first tube and the advancing rollers for the second tube are properly matched so both tubes advance at the same rate. 
   SUMMARY OF THE INVENTION 
   The present invention provides a method and apparatus for producing a partitioned package having an inner tube containing a first material and an outer tube containing a second material, where the outer tube is advanced, thereby causing the material within the outer tube to advance and drag the inner tube along therewith at substantially the same rate. Only the outer tube is engaged by the apparatus, yet the apparatus produces a partitioned compartment where all components are advanced substantially similar rates. The method and apparatus of the present invention are particularly suited for producing resin cartridges for use in anchoring mine roof bolts where the inner tube is manufactured from a weaker material than the outer tube. Such an arrangement reduces the cost of materials and minimizes the force needed to puncture the inner tube which provides for more rapid mixing of the resin cartridge components. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a packaging device advancing a tube received within a larger tube made in accordance with the present invention; 
       FIG. 2  is a cross-section of the device shown in  FIG. 1  taken along line  2 - 2 ; 
       FIG. 3  is a cross-section of the device as shown in  FIG. 1  taken along line  3 - 3 ; 
       FIG. 4  is a cross-section of the device shown in  FIG. 1  taken along line  4 - 4 ; 
       FIG. 5  is a cross-section of the device shown in  FIG. 1  taken along line  5 - 5 ; 
       FIG. 6  is a cross-section of the device shown in  FIG. 1  taken along line  6 - 6 ; 
       FIG. 7  is a cross-section of the device shown in  FIG. 1  taken along line  7 - 7 ; 
       FIG. 8  is a cross-section of the device shown in  FIG. 1  taken along line  8 - 8 ; 
       FIG. 9  is a cross-section of the device shown in  FIG. 1  taken along line  9 - 9 ; 
       FIG. 10  is a side view of a two-component package produced according to the present invention; 
       FIG. 11  is a cross-section of the package shown in  FIG. 10  taken along line  11 - 11 ; and 
       FIG. 12  is a perspective view of another embodiment of the packaging device of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention is described with reference to producing two-component cartridges containing resin and a catalyst component for effecting polymerization of the resin upon rupture of the cartridge and mixing of the components, particularly for use in anchoring mine roof bolts. However, this use is exemplary only and is not meant to be limiting. The resin cartridges produced using the present invention may be used to anchor other structural components. Additionally, the two-component cartridge of the present invention may be used for housing other components that may or may not be reactive with each other. For purposes of the description hereinafter, the terms “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom” and derivatives thereof shall relate to the invention as it is oriented in the drawing figures. However, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the invention. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting. 
   Referring to  FIG. 1 , the apparatus  2  of the present invention includes a first forming member  4  mounted on a support  6  and surrounding a first fill tube  8  and a second forming member  10  mounted on a support  12  and surrounding both of a second fill tube  14  and the first fill tube  8 . A web  16  of a first pliable film moves continuously from a supply roll (not shown) and passes under at least one roller  18  and upwardly and over a curved edge  20  of the first forming member  4 . The first forming member  4  is cut and shaped to cause the first web  16  to reverse its direction and to guide edges of the first web  16  downwardly into a convoluted tube forming relation around the first fill tube  8  as shown in  FIG. 2 . As the first web  16  travels down the outside of the first fill tube  8 , the edges of the web  16  overlap yielding an inner tube  22  with longitudinally extending overlapping portions  24  as shown in  FIG. 3 . The inner tube  22  advances over a first collar  26  having a larger cross-sectional dimensions than the first fill tube  8 , as shown in  FIG. 4 . The first fill tube  8  and the first collar  26  may have cylindrical cross-sections as shown in  FIG. 4  at the upper end of first collar  26 . At the lower end of first collar  26  as shown in  FIG. 5 , the cross-sectional configurations of both of the first collar  26  and the first fill tube  8  are altered. At this location, the first fill tube  8  has a non-circular configuration and the collar  26  has a cylindrical exterior surface and an interior configuration that corresponds to the configuration of the first fill tube  8 . A heat seal is applied at  28  to the overlapping portions  24  to seal the inner tube  22 . 
   Referring to  FIGS. 6 and 7 , a second web  30  of pliable film extends over a roller  32  and upwardly and over an upper curved edge  34  of the second forming member  10  to surround both the inner tube  22  (and the first fill tube  8 ) and the second fill tube  14 . The second fill tube  14  has a non-circular configuration and may generally have larger cross-sectional dimensions than the first fill tube  8 . As the second web  30  travels past the second forming member  10  along the outside surfaces of the inner tube  22  and second fill tube  14 , an outer tube  36  is formed from the second web  30  in an overlapping relationship with the second forming member  10 . The first and second fill tubes  8  and  14  have respective curved portions  40  and  42  that together generally provide a curved surface onto which the outer tube  36  is formed with longitudinally extending overlapping portions  38 . 
   As shown in  FIG. 8 , the outer tube  36  passes over a second collar  44  having a longitudinal slot  46 . A heat seal is applied at  48  to the overlapping portions  38  of the outer tube  36 . The overlapping portions  24  of the inner tube  22  and the overlapping portions  38  of the outer tube  36  may be positioned at different radial positions so that the heat seal produced on the outer tube  36  has minimal impact on the previously produced heat seal of the inner tube  22 . The inner surface  50  of the second collar  44  is configured to correspond to the curved exterior surface  42  of the second fill tube  14  and frictionally engage the first fill tube  8 . The second collar  44  may include enlarged portions  52  that are sized and configured to exert sufficient force against the inner tube  22  and the first fill tube  8  so as to retain the fill tubes  8  and  14  and the first tube  22  within the second collar  44 . Alternatively, the second collar  44  may be fixed to the second fill tube  14  along a portion of surface  42  such as by welding. 
   At a lower end of the package forming apparatus  2 , the first full tube  8  and the second fill tube  14  have reduced cross-sectional dimensions. In one embodiment, fins  54  extend from opposing sides of the second fill tube  14  as shown in  FIG. 9 . Opposing portions  56  of the outer tube  36  are each engaged between a fin  54  and a pair of feed wheels  58 . The feed wheels  58  engage the outer tube  36  for continuous advancement thereof towards a tube constricting and sealing unit (not shown). 
   Another embodiment of the present invention is shown in  FIG. 12 . Apparatus  102  includes many of the same features and components as apparatus  2 . At the lower end, a pair of endless belts  104 ,  106  traveling in respective directions A, A′ over rollers or wheels  108  frictionally engage the outer tube  36 . The outer tube  36  is engaged between the belt  104  and the first fill tube  8  in the vicinity of the overlapping portions  24  of inner tube  22 . Likewise, the outer tube  36  engages between the belt  106  and the second fill tube  14  in the vicinity of the overlapping portions  38  of the outer tube  36 . In another embodiment, the outer tube  36  is gripped and advanced by a continuous vacuum belt (not shown). Apertures through the vacuum belt permit a vacuum to be applied to the outer tube  36  so as to grip and advance the outer tube  36 . 
   Referring to  FIGS. 10 and 11 , a first material  60  is delivered into the first fill tube  8  and a second material  62  is delivered into the second fill tube  14  such that a resulting two-component package  64  has a cross-sectional configuration generally as shown in  FIG. 11 . It has been found that active advancement of the outer tube  36  alone is needed to advance both the inner tube  22  and outer tube  36  and their contents through the apparatus  2  or  102 . The outer tube  36  exerts drag on the second material  62  that, in turn, exerts drag on the inner tube  22  at a level sufficient to advance the inner tube  22  (and the first material  60 ) at a rate substantially the same as the rate of advancement of the outer tube  36 . Substantially the same rate means that the outer tube  36  and the inner tube  22  advance at rates which do not produce undesirable tension or undesirable slack in the partitioned package  64  as can occur if one of the tubes advances more quickly than the other. 
   As shown in  FIG. 10 , the resulting two-component package  64  includes an inner tube  22  within an outer tube  36  constricted at each end  66 . The two-component package  64  of the present invention may be produced from any heat-sealable, pliable film. The particular material selected for the webs  16  and  30  may be determined by the end-use of the two-component package  64 . Polyethylene or polypropylene may be suitable for less aggressive environments where the risk of rupture or premature rupture is low. Stronger material is generally more costly but may be desirable in more aggressive environments such as in underground mining. In one embodiment, the outer tube  36  is produced from a stronger film while the inner tube  22  is produced from a weaker film. By using a weaker material for the inner tube  22 , the force needed to puncture and shred the outer tube  36  will generally be sufficient to puncture and shred the inner tube  22 . This ensures more effective mixing of reactive components. Accordingly, a resin cartridge produced according to the present invention provides for enhanced puncturability and mixing of the contents within the two tubes. A difference in strength between the outer tube  36  and inner tube  22  can be achieved by using a thinner film for web  16  than for web  30 . For example, when both of webs  16  and  30  are produced from polyethylene terephthalate, the web  30  may be 0.0005 to 0.003 inch (0.5 to 3 mil) thick and the web  16  is 25 to 75% thinner than the web  30 . Alternatively, a stronger material may be used for the web  30  than for the web  16 , such as polyethylene terephthalate for web  30  and polyethylene or polypropylene for web  16 . In such a case, the weaker web has a lower tensile modulus. It has been found that when the two-component package  64  of the present invention is produced using a material for the inner tube  22  having a lower modulus than the material of the outer tube  36 , the inner tube  22  functions as a gasket to the outer tube  36  upon constriction and sealing of package  64  at the ends  66 . Such an arrangement enhances the seal at the ends  66  of the package  64 . 
   In addition, by using different materials for the inner tube  22  and outer tube  36 , the tubes may have different vapor barrier properties. In a resin cartridge, to avoid loss of water from the catalyst compartment, the inner tube  22  may be produced from a material having low water permeability such as high-density polyethylene. Likewise, it can be beneficial for the outer tube  36  to exhibit low permeability to organic solvents present in a polymerizable resin composition. For example, polyester is one suitable material for the outer tube  36  to minimize permeation of organic materials therethrough. The structure of a resin cartridge produced according to the present invention is also beneficial to retaining the integrity of the resin cartridge. Water loss from a resin cartridge can make the cartridge limp and increases the viscosity of the components mixed. Minimized water loss improves the shelf life of the resin cartridge. Escape of water in the catalyst component from the resin cartridge is minimized because the catalyst component is surrounded by the inner tube  22 , the polymerizable resin and outer tube  36 . 
   In general, the first material  60  and the second material  62  are flowable materials such as fluids (typically liquids) and flowable solids such as powders or other particulate matter. For producing resin cartridges for use in anchoring mine roof bolts, the second material  62  may be a polymerizable resin such as a polyester resin and the first material  60  may be a polymerization catalyst. The sizes and relative dimensions of the inner tube  22  and outer tube  36  may vary depending on the end use of the two-component package  64 . Mine roof resin cartridges typically have an overall diameter of about 0.75 to 1.5 inch and a length of 12 to 60 inches. 
   Whereas particular embodiments of this invention have been described above for illustration purposes, numerous varieties of the details of the present invention may be made without departing from the invention as defined in the appended claims.