Abstract:
A closing member  1  for compressed air carrying polygonal tubes, which is inserted in a sealing manner into the polygonal tube at one end thereof. The closing member  1  includes an elastic sealing element  3 , and the closing member is constructed such that it biases in its inserted state the sealing element  3  in such a manner that it seals and secures the closing member  1  relative to the polygonal tube  8 . Closing members of this type are used to seal mounting tubes in yarn spinning machines with pneumatically loaded top roller support and weighting arms.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   The present application is a continuation of international application PCT/EP2003/013263, filed 26 Nov. 2003, and which designates the U.S. The disclosure of the referenced application is incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to a closing member for compressed air carrying polygonal tubes of the type used as a mounting rod for the drafting system in a yarn spinning machine. 
   In such spinning machines, pneumatically loadable top roller support and weighting arms are used, which are secured by means of brackets to a mounting rod of the machine. The mounting rod is hollow and serves at the same time as a compressed air delivery line. A drafting system of this type is described, for example, in DE 198 29 403 A1. 
   DE 198 30 048 A1 discloses a mounting rod that is formed from polygonal tube sections, with each tube section being provided at its ends with closing members. A mounting rod that is composed of individual tube sections permits a modular construction of the mounting rod and compressed air supply for spinning machines of different lengths. The closing members are inserted in a sealing manner into the ends of the polygonal tube sections. Between the polygonal tube sections, the compressed air is conducted through a connecting tube section which interconnects the closing members of two adjacent sections. 
   Sealing of non-circular hollow sections with elastic sealing elements, such as O-rings with a circular cross section, or with special section rings, presents problems, inasmuch as irregularities of the special section of the sealing element causes in the latter only a certain equalization of internal tension, without the sealing element filling all zones of the hollow section in a uniform and sealing manner. It is therefore preferred to use in the case of polygonal hollow sections, pasty sealing substances of a suitable viscosity, which must completely fill a sealing channel that is formed by the hollow section and an inserted sealing element. It is however difficult to fill the sealing channel evenly and completely, as well as in a process safe manner in the case of series production. This requires a great expenditure for production and testing. The sealing effect is often not stable for a long duration because of the aging behavior of the sealing substance and because of operational stress, for example, as a result of pressure changes. Thus a reliable, lasting sealing is not ensured. 
   If leakages occur in operation, sealing elements of the described type are hard to disassemble and cannot be reused. It is therefore often necessary to exchange the entire special section tube length. Likewise, the sealing substance is able to only a very limited extent retain the sealing element in the required position against the inner pressure in the special section tube. This requires additional special measures, for example, the installation of pins for securing the sealing element against axial displacement. 
   If an adhesive is used as sealing substance to increase the hold of the sealing element in its position at the end of the polygonal tube, it will be difficult and costly to disassemble the closing member. In this case, the closing members and, possibly, even the polygonal tube will no longer be suited for immediate reuse. 
   At their ends, the polygonal tubes are supported in recesses of brackets that are also known as stands, and secured in position by means of screw connections. To this end, a mounting screw extends through the special-section tube in its end region, which also mounts the respective closing member. By tightening the mounting screw, the polygonal hollow section may undergo elastic or plastic deformations, whereby the sealing effect is additionally put at risk. 
   Based on the foregoing state of the art, it is an object of the invention to overcome the above limitations and deficiencies of the known closing members. 
   SUMMARY OF THE INVENTION 
   The above and other objects and advantages of the invention are achieved by the provision of a closing member which is configured for being inserted in an end of a compressed air carrying polygonal tube on a yarn spinning machine, and which comprises an elastic sealing element, and with the closing member being configured such that it axially biases in its inserted state the sealing element, whereby the sealing element expands so as to seal the closing member relative to the polygonal tube. 
   The closing member of the invention seals the polygonal tube in a reliable and stable manner for a long duration. It is no longer necessary to secure it in addition, for example, by means of formfitting retaining pins against displacement by the air pressure that builds up in the interior of the polygonal tube, since the closing member is adequately secured in a force-locking engagement, when its sealing function is activated. In comparison with closing members of the known prior art, assembly and disassembly of the closing members are facilitated. The closing members and polygonal tubes are reusable, without having to perform additional labor, such as, for example, cleaning. 
   A closing member is constructed such that compressed air is allowed to flow from the polygonal tube through the closing member and into the closing member of an adjacent tube. This permits applying axial pressure to the sealing element in a uniform manner, and achieving a reliable sealing effect. 
   The closing member preferably comprises an end piece and a counterpart with the sealing element being constructed and arranged between the end piece and the counterpart. This permits sealing and securing at the same time, after the closing member has been inserted into the polygonal tube. It is also easy and simple to release the closing member from its secured position and to remove it from the polygonal tube. 
   The end piece and the counterpart are interconnected by a threaded member that extends through the sealing element, and by tightening the threaded member the end piece and the counterpart move toward each other and bias the sealing element with axial pressure. This also provides adequate space for the compressed air channel, which ensures the necessary passage of the compressed air, and it permits in addition the threaded member to engage the counterpart in the center, which counteracts a tilting of the counterpart when the threaded member is tightened. In addition, the configuration of the end piece and counterpart in the region of the compressed air channel makes it possible to prevent the parts of the closing member from being joined in an incorrect position. 
   The insertion of a connecting tube into the opening of the closing member, which is formed in its end face by the compressed air channel, ensures the passage of compressed air between two polygonal tubes in a simple manner. 
   To insure adequate and reliable sealing effect, the length of the sealing element preferably amounts to at least 1.5 times its wall thickness. Also, the sealing element is preferably formed of rubber which provides desirable elastic properties. 
   The end piece of the closing member may include a recess which is sized to receive differently sized mounting screws. A supporting contour provided on both sides of the recess of the end piece counteracts a deformation of the hollow tube even in the case of an excessive torque applied to the mounting screws. 
   The closing member is constructed such that it seals the interior of the polygonal tube toward the recess. As a result, the mounting points of the polygonal tube section are arranged in a region of the closing member, which does not carry compressed air. The openings in the polygonal tube, through which the mounting screws of a screw connection extend between the polygonal tube and the machine, need not be sealed. The shape and the position of the recess ensure an adequate staying of the end of the polygonal tube. 
   The closing member of the invention seals the interior of the polygonal tube in a reliable and stable manner for a long duration. Simultaneously with the sealing effect, it is possible to secure the closing member in its position against the air pressure prevailing in the interior of the polygonal tube without additional auxiliary means. A possibly needed repair of the polygonal tube that forms the mounting rod, is easily possible and requires little labor for disassembly and assembly also when the polygonal tube is installed as a part of a mounting rod between other polygonal tubes. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further details of the invention will become apparent from the embodiment that is described in greater detail below, with reference to the Figures, in which: 
       FIG. 1  is a perspective view of the individual parts of a closing member which embodies the invention before its assembly; 
       FIG. 2  is a partially sectioned view of the parts of the closing member shown in  FIG. 1 ; and 
       FIG. 3  is a sectional view of the end region of two polygonal tubes, each with a closing member and a connecting tube and taken along the line A-A of  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring more particularly to the drawings, there is illustrated a preferred embodiment of a closing member at  1  which embodies the invention. The member  1  comprises an end piece  2 , a sealing element  3 , and a counterpart  4 , which are aligned along a central axis which is shown by the dashed line in  FIG. 1 . The member  1  also includes a threaded member  5 , and a sealing washer  6 , which are also positioned along the central axis. 
   The end piece  2  comprises a guide section  7 , whose outer contour is adapted to the inner contour of a polygonal tube  8  shown in phantom lines in  FIG. 1 . The polygonal tube  8  is made square or of some other rectangular configuration. Adjacent the guide section  7  is a sealing section  9  with an outer contour of the same shape. The width and height of the outer contour of sealing section  9  are made somewhat smaller than the width and height of the guide section  7 . 
   At the end of the end piece  2  that faces the sealing section  9 , a stop  10  is formed, which interacts with an end face  11  of the polygonal tube  8 , and prevents the closing member  1  from being pulled or pushed into the polygonal tube  8  beyond a desired position. The guide section  7  includes a transverse recess  12 . Through this recess  12  and bore holes  13 , a mounting screw extends, which is not shown for reasons of simplification, and which is used to secure the polygonal tube to a bracket or stand. On both axially separated sides of the recess  12 , a supporting contour  14 ,  15  is formed, which counteracts a deformation of the hollow polygonal tube  8 . The recess  12  in end piece  2  is dimensioned adequately large for the mounting screw, so as to be universally suited and usable for different screw sizes and screw positions that are dependent on the design of the stands. Along the central axis, the stop  10  includes an axial opening of a feed channel  16  for the threaded member  5 , and in off-center relationship, an outlet of a connecting channel  17  for carrying the compressed air. 
   The contoured shape of the sealing element  3  corresponds to the polygonal tube  8  and sealing section  9 , with the inner contour of the sealing element  3  being adapted to the outer contour of the sealing section  9 , and the outer contour of the sealing element  3  to the inner contour of the polygonal tube  8 . The sealing element  3  preferably consists of elastically deformable rubber. The wall thickness T of the sealing element  3  is somewhat smaller than the spacing that is present between the inner side of the polygonal tube  8  and the outer side of the guide section  7 , when the closing member  1  is inserted into the polygonal tube  8 . The length L of the sealing element  3  amounts to a multiple of the wall thickness T, and is dimensioned such that the counterpart  4  can adequately bias the sealing element  3  with axial pressure. 
   The counterpart  4  comprises a hollow section  18  of the same contoured shape as the sealing element  3 , and is closed at one end by a rear wall  19  as best seen in  FIG. 2 . The rear wall  19  includes in inwardly directed relationship a support element  20  and a channel element  21 . With its edge  22 , the hollow section  18  projects beyond the support element  20 . The channel element  21  projects even beyond the edge  22 . The counterpart  4  can be joined in mating relationship with the end piece  2 , only when the somewhat projecting channel element  21  assumes its correct position. In the embodiment shown in  FIG. 1 , the correct position of the channel element  21  is on the top left in the counterpart  4 . This ensures the necessary flow of the compressed air. Through the center of the rear wall  19  and support element  20 , a bore  23  extends, into which a screw thread is cut. Both the end piece  2  and the counterpart  4  preferably consist of a suitable metal, such as die-cast zinc. 
   The sectional view of  FIG. 2  shows further details of the configuration of closing member  1 . In the interior of end piece  2 , the feed channel  16  changes to a smaller diameter. The transition to the smaller diameter of the feed channel  16  is shaped as a shoulder  24 . The connection channel  17  changes to a compressed air channel  25 , which has a smaller operative cross section than the connection channel  17 . 
   In the counterpart  4 , one can note a passageway opening  26  for the compressed air. The channel element  21  forms a part of the extension of compressed air channel  25 . 
   When assembling the closing member  1 , one begins with sliding the sealing element  3  onto the sealing section  9  of the end piece  2  as far as the guide section  7 . Subsequently, one inserts the threaded member  5  together with the sealing washer  6  into the feed channel  16 , with the sealing washer  6  being placed on the shoulder  24 . The end of threaded member  5  is turned into threaded bore  23  of the counterpart  4  only so far that it engages the screw thread, and that the counterpart  4  does not yet exert an axial pressure on the sealing element  3 . 
   The thus preassembled closing member  1  is inserted into the end of the polygonal tube  8  as far as the stop  10 . Subsequently, one tightens the threaded member  5 , whose head includes a hexagon socket  27 , so that the end piece  2  axially exerts with its edge  22  a pressure on the sealing element  3 . This causes the sealing element  3  to expand against the inner side of the polygonal tube  8 , to secure the position of the closing member  1  against the air pressure developing in the interior of the polygonal tube  8 , and to form a seal in an airtight manner between the polygonal tube  8  and the end piece  2 . 
   A closing member  1  in this state is shown in  FIG. 3 . The compressed air is allowed to flow through the closing member  1  from the passageway opening  26 , via the compressed air channel  25  to the connection channel  17 , or in the opposite direction. Adjacent at a small distance from the polygonal tube  8  is a second polygonal tube  28 . A closing member  29  inserted into the polygonal tube  28  is made mirror-inverted with closing member  1 . The closing member  1  and closing member  29  are interconnected by a connection tube  30 , which is inserted with its ends into the connection channel  17  and connection channel  31 . With that, compressed air is allowed to flow unimpeded between the polygonal tube  8  and polygonal tube  28  through compressed air channels  25  and  33 . The connection tube  30  is sealed by means of O-ring seals  32  as disclosed in DE 198 30 048 A1. 
   The invention is not limited to the described embodiments. Within the scope of the invention, alternative configurations are possible, in particular of the end piece and the counterpart.