Abstract:
A method and apparatus for performing a manufacturing operation at a plurality of locations along the length of a previously fabricated flexible conduit. The apparatus comprises a driving mechanism, a manufacturing station, and a support device. The conduit is first fed through the manufacturing station. The manufacturing station then performs the manufacturing operation at a plurality of locations along the length of the conduit. The support device within the conduit is not attached to any other structure and provides structural support at the manufacturing station during the manufacturing operation and remains at a generally fixed axial and functional location while the conduit continues to move axially.

Description:
BACKGROUND OF THE INVENTION 
   The present invention is directed generally to the field of flexible conduits, typically relatively long lengths of conduits, and more particularly to methods and apparatus for performing various fabrication operations at spaced intervals along the length of such flexible conduits. The present invention is also directed to the flexible conduit assemblies manufactured through the use of the method and apparatus. The invention finds application in the manufacture of flexible plastic tubing assemblies used in a variety of fields, including, for example, single point battery watering systems. 
   Flexible conduits are used in many specialized applications. For instance, flexible conduits may be used in sprinkler systems, irrigation systems, and air pumps. Flexible conduits may also be used in single point watering (SPW) systems to supply battery cells with fluids. In such systems, a single conduit or tube supplies fluids to a plurality of interconnected tubes. Each tube in turn supplies fluids to a plurality of battery cell refill valves. 
   Conventional flexible conduits are generally fabricated by plastic molding. However, for many specialized applications, conduits must be further modified after initial fabrication. For instance, in single point battery watering systems, each conduit or tube in a tubing network must be fitted with a plurality of inserts or fittings that can connect and supply fluids to battery cell refill valves. Likewise, tubes in sprinkler systems must be fitted with a plurality of fittings that can connect to sprinklers. In other systems, there may be a desire to aesthetically modify tubes by embossing, engraving or hot stamping them with displays such as commercial logos. 
   The modification of flexible conduits for various applications is challenging because the tubing is susceptible to folding and collapsing under pressure. Thus, any modification that requires the application of force to the tubing wall may affect a tube&#39;s structural integrity or lead to poor results. For instance, a tube may fold during a drilling process and result in the formation of multiple apertures at undesired places. Likewise, a tube may collapse during embossing such that the embossed structure is not properly positioned. In other instances, more rigid tubes may crack or break during a modification step. Therefore, there is a need for a method and apparatus to provide internal structural support to a conduit to prevent collapse during operations on the wall of the conduit at periodic intervals. The present invention addresses this unmet need. 
   The innovative conduit assembly of the present invention facilitates the installation of fluid distribution systems by prefabricating the conduit and fittings or other components prior to the time of installation. For example, in the case of single point battery watering systems, the fittings are prefabricated and joined to the conduit so that the finished assembly may be installed on the battery with little or no cutting and connecting of the conduit assembly in the field. The same installation advantages arise in a variety of other fields, such as lawn irrigation or patio misting systems. 
   SUMMARY OF INVENTION 
   The present invention provides a method and apparatus for performing a manufacturing operation at a plurality of locations along the length of a flexible conduit with a longitudinally extending sidewall that defines an enclosed inner cavity. The apparatus of the present invention comprises a driving mechanism that engages the conduit and feeds it along a predetermined travel path. The apparatus of the present invention also comprises a manufacturing station that is positioned along the conduit travel path and adapted to assemble the manufactured component to the conduit at a plurality of locations along its length. In addition, the apparatus of the present invention comprises a support device that is positioned within the conduit at a point along the length of the conduit that is coincident with the manufacturing station, and wherein the support device remains in position as the conduit continues to move along its path of travel and through the manufacturing station. 
   In the first step of the manufacturing method of the present invention, the conduit is fed through the manufacturing station. The manufacturing station is then operated periodically to perform the manufacturing operation at a plurality of locations along the length of the conduit. During the manufacturing operation, the support device located within the conduit maintains the integrity of the conduit and provides structural support. 
   In the preferred embodiment of the present invention, the manufacturing apparatus utilizes a pneumatic valve driving mechanism. In addition, the preferred manufacturing apparatus of the present invention utilizes a floating mandrel as the support device. Furthermore, in the preferred embodiment, the manufacturing station comprises an injection molding machine for molding multiple fittings onto the conduit. The preferred manufacturing station also contains a wall piercing device for introducing apertures into the conduit. 
   In the preferred method of the present invention, the pneumatic valve feeds the conduit to the manufacturing station. The fittings are then injection molded onto the conduit at periodic intervals. Next, a piercing tool introduces holes into the conduit by accessing the conduit through apertures molded into the fittings. During the process, the floating mandrel within the conduit provides internal structural support. 
   The preferred conduit assembly of the present invention comprises a length of flexible conduit, generally a relatively long conduit body ranging from a few to many linear feet in length. A plurality of fittings or other manufactured components are integrally preassembled to and preferably molded onto the conduit body, with the manufactured components being positioned at spaced locations along the length of the conduit body. Typically, the individual components are spaced to accommodate the particular operating system in which the conduit assembly is used. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features which are characteristic of the present invention are set forth in the appended claims. However, the invention&#39;s preferred embodiments, together with further objects and attendant advantages will be best understood by reference to the following detailed description taken in connection with the accompanying drawings in which: 
       FIG. 1  is a perspective view of one embodiment of the manufacturing apparatus of the present invention. 
       FIG. 2  is an enlarged cross sectional view of a portion of the apparatus shown in  FIG. 1 . 
       FIG. 3  is a side view of the manufacturing apparatus in  FIG. 1 . 
       FIG. 4A  is a top view of the manufacturing station in  FIG. 3  during a molding operation. 
       FIG. 4B  is a top view of the manufacturing station in  FIG. 3  between molding operations. 
       FIG. 5  is an enlarged and partial cross sectional view of the manufactured component in the form of a fitting as assembled to a conduit in the practice of the present invention. 
       FIG. 6  is an enlarged partial cross-sectional view taken along line  5 - 5  in  FIG. 5 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows the preferred embodiment of the manufacturing apparatus of the present invention. In this embodiment, manufacturing apparatus  10  comprises a driving mechanism  11  with one or more cylinders  21  for feeding conduit  12  into the apparatus. Manufacturing apparatus  10  is also provided with support device  17  for supporting the conduit&#39;s sidewall and maintaining its integrity during the manufacturing process. Manufacturing apparatus  10  also comprises a plurality of restraints  13  for restraining the axial movement of support device  17 . Restraints  13  also hold and guide the conduit through a predetermined path of travel. 
   In the preferred embodiment, a manufacturing station  25  comprises an injection molding machine  14  for molding a plurality of fittings  15  around the conduit. Manufacturing station  25  may also include a piercing tool, such as heated pin  16 , for introducing a plurality of holes into the conduit. It is also desirable that manufacturing apparatus  10  comprise feed reel  18  for supplying conduit  12  and a frame or base  20  for mounting various components of the apparatus. 
   As shown in  FIG. 2 , it is desirable that conduit  12  be a flexible and hollow tube or corrugated conduit with a plurality of annular recesses grooves  24 . It is also desirable that conduit  12  be composed of a plastic, such as polypropylene or polyurethane. However, in other embodiments, conduit  12  may be composed of other relatively flexible material. 
   In one preferred embodiment, driving mechanism  11  utilizes a pneumatic valve driver that reciprocates to move the conduit along its predetermined path of travel. As shown in  FIG. 2 , it is desirable that cylinder  21  operates a plurality of grippers  22  that engage recesses  24  on conduit  12 . The grippers  22  may be spring biased to feed conduit  12  into manufacturing station  25  during the forward or driving stroke of driving mechanism  11 . 
   In the preferred embodiment, the driving mechanism  11  feeds conduit  12  by intermittent motion. In other embodiments, conduit  12  may fed into the apparatus by continuous motion. In further embodiments, driving mechanism  11  may be an alternative mechanical structure, such as motor driven rollers or geared driving wheels. In other embodiments, an operator may manually feed conduit  12  into manufacturing apparatus  10 . 
   Turning again to  FIG. 1 , it is shown that support device  17  is an elongated rod with a right angle bend. It is located within the inner cavity of conduit  12  and spans the path of travel of the conduit from the driving mechanism to the manufacturing station  25 . Due to its right angle structure and its orientation relative to restraints  13 , support device  17  does not move substantially within conduit  12  as the conduit itself moves. In particular, first restraints  13 a prevent vertical movement of the support device, while restraints  13 b prevent horizontal movement of the support device. Other mechanical restraints that will maintain the axial location of the support device relative to the manufacturing station  25  apparent to those of skill in the art. 
   Support device  17  is a floating mandrel. Floating mandrels have been used for molding tubes from molten plastic. Floating mandrels have also been used to expand flattened tubes. However, floating mandrels have not been used to provide internal structural support to conduit or tubes of significant length during a manufacturing process. Such a use for a floating mandrel has not been disclosed or suggested in the art prior to this invention. 
   Support device  17  is preferably an inflexible plastic or metal and is provided with a generally tapered tip. It is desirable that support device  17  be comprised of or coated with a high lubricity material, such as polytetrafluoroethylene. Most preferably, support device  17  is provided with a cross sectional geometry most suited for supporting the sidewall of the conduit during the manufacturing operation. Other embodiments of support device  17  that are suitable for the present invention are disclosed in U.S. Pat. Nos. 3,104,464, 4,765,121, 5,063,018, and 5,392,626. The disclosures of these patents are incorporated into this application by reference. 
   The preferred method of performing the manufacturing operation of the present invention is illustrated in  FIGS. 1 and 3 . In the first step of the preferred method, the forward or free end of conduit  12  is inserted into aperture  24  on driving mechanism  11 . Next, driving mechanism  11  is operated to feed conduit  12  into manufacturing station  25 . During the feeding of the conduit  12  toward the manufacturing station  25 , the conduit passes over the first or near end of the support device. In this manner, the conduit is treaded over the support device and is supported by it in the manufacturing station. The conduit is directed along it path of travel to manufacturing station  25  by restraints  13 . Once the conduit reaches the manufacturing station, injection molding machine  14  forms the fitting  15  over the conduit. In the preferred embodiment, the fitting  15  is molded from the same plastic material as used in fabrication of the conduit  12 . As a result, the fittings are integrally joined to and fully sealed with the conduit since during the molding operation at least a portion of the conduit sidewall becomes molten and fully cures with the injected plastic forming the fitting. Fitting  15  includes a body  26  and top  27  with an aperture  28 . Next, the molded fitting reaches the area of the manufacturing station where the piercing tool  16 , which is preferably a heated metal pin, then forms an aperture in the sidewall of conduit  12 . As the conduit exits the manufacturing station  25 , it passes off the support device&#39;s second or far end, since the support device is prevented from moving with the conduit by restraints  13 . 
   The manufacturing cycle is repeated at periodic intervals as conduit  12  passes through manufacturing station  25 . As a result, conduit  12  is molded with a plurality of fittings  15 . During this process, support device  17  remains in conduit  12  at the manufacturing station  25  and provides internal structural support. The resulting prefabricated conduit assembly may be of a length ranging from just several inches to as much as fifty to several hundred feet, and may be wound on a reel for ease of shipment and handling. 
   As shown in  FIG. 5 , the molded fitting comprises a top  27  and an aperture  28 . Aperture  28  generally serves to provide access to conduit  12 . Likewise, top  27  generally serves as an insert for the connection of conduit  12  to secondary structures, such as battery cell refill valves. To provide a sealing mechanism for such connections, top  27  may further comprise recess  30 , where o-ring  31  may be inserted. 
   As illustrated in  FIG. 6 , fitting  15  also comprises body  26  surrounding conduit  12 . Body  26  is sealed tightly around conduit  12  by a plurality of protrusions  32  that are in tight contact with grooves  24  on conduit  12 . As discussed above, where the fitting and the conduit are made from the same or compatible plastic materials, they will tend to fuse into an integral assembly during the injection molding of the fitting. 
   In the preferred embodiment, the manufacturing apparatus and method of the present invention may be used to produce tubing networks for use in single point battery watering systems. In this embodiment, fittings  15  serve as inserts for connection to a plurality of refill valves. In addition, conduits  12  may be interconnected to one another by a plurality of connectors. Examples of such tubing networks are described in detail in U.S. Pat. Nos. 5,832,946, 5,284,176, 5,482,794, and 5,453,334. The disclosures of these patents are hereby incorporated by reference. When used in a single point battery watering system, the conduit is preferably of a length sufficient to accommodate the installation of the conduit assembly to one or more batteries or at least to a significant subset of the battery, and the fittings  15  are spaced along the length of the conduit to correspond to the spacing of the refill valves positioned in each of the battery cells. This will typically call for the fittings  15  to be spaced from about two to ten inches along the conduit length. The prefabricated conduit assembly is installed into the battery watering system simply by pressing the fittings onto the cell refill valves, without the need for cutting the conduit and connecting the individual fittings in the field. End caps or plugs may be used to block the free ends of the conduit assembly or any unused fittings. This installation technique provides substantial labor and time savings over conventional systems. 
   It is to be understood that there are various embodiments of the present invention. For instance, in one embodiment, a nozzle may be molded onto the conduit. In other embodiments, fitting  15  may be absent from conduit  12 . In such embodiments, pin  16  may access conduit  12  directly. In other embodiments, pin  16  may be a needle or a drill instead of a heated pin. In further embodiments, the manufacturing station may contain a heated block or plate for thermoforming, hot stamping, engraving, or embossing conduit  12  at periodic intervals. In other embodiments, multiple pins or plates may be present at the manufacturing station. 
   As apparent by the multiple embodiments, the present invention may be used to produce tubing networks for a variety of applications. For instance, the apparatus and method of the present invention may be used to manufacture sprinkler systems. The present invention may also be used to produce tubes with engraved logos, trademarks, or other displays. In further embodiments, the present invention may be used to produce tubing networks for use in irrigation systems and air pumps. Such tubing networks could be manufactured by various methods, such as blind riveting, drilling, piercing, embossing and thermoforming. 
   There are other numerous embodiments of the present invention which, while not expressly described above, are clearly within the scope and spirit of the invention. The above description is therefore intended to be exemplary only and the scope of the invention is to be determined solely by the appended claims.