Abstract:
A web infeed device for rotary printing presses includes a pointed nose piece having concave side portions. The flexible infeed element is received in a guide, and driving elements are provided for driving the infeed element along the guide.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to printing devices and more particularly to a web infeed device for rotary printing devices. 
     U.S. Pat. No. 5,967,036 describes a web infeed device for rotary printing presses, which permits a web to be fed through the printing press. A flexible, finite infeed element for holding a lead edge of a web runs in a guide or track. Balls are inserted in openings of the infeed element at spaced-intervals, and travel within a cross-cut in the guide. Drive elements can drive the balls and thus move the infeed element through the printing press to feed the web. U.S. Pat. No. 5,967,036 is hereby incorporated by reference herein. It has been known for the tip of the infeed element described therein to jam in the guide, for example in curves or gaps. 
     U.S. Pat. No. 5,320,039 discloses a web engagement system for an off-reel printing press in which a guide piece is accommodated in a guide channel. The guide piece preferably is a flexible plastic section with a square cross-section. The front part is tapered and a rear part is split. 
     U.S. Pat. No. 4,987,830 discloses a paper feed device for rotary presses having a spindle shaped linear member. The linear member is made of synthetic resin or leather, with caps being made of a rather hard material. 
     The devices of the &#39;039 and &#39;830 are long flexible members that ran in guides and contact the guides over a large length. The friction generated by flexible members passing over a curved section is subject to what is known as the capstan effect, which causes frictional forces to increase exponentially as the flexible member wraps around the surface. 
     BRIEF SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a web infeed device with reduced friction and improved feeding properties. 
     The present invention provides a web infeed device for rotary printing presses comprising an infeed element having a flexible section and a pointed nose piece having concave side portions; a guide, the flexible infeed element being received in the guide; and driving elements for driving the infeed element along the guide. 
     The nose piece of the present invention with the concave side portions provides for excellent feeding while reducing friction with the guide. 
     The flexible section preferably includes a flat band-shaped metal piece. The band-shaped piece may include holes, and balls located in the holes. 
     The pointed nose piece preferably is made of rigid material, and preferably has a cut out at a rear end for receiving the band-shaped metal piece. 
     A rear section of the nose piece preferably is curved, to aid in rearward movement of the infeed element. 
     Preferably, the nose piece is symmetrical about a longitudinal plane, preferably a plane defined by the flexible section. Most preferably, the nose piece is fully symmetrical about a longitudinal axis. 
     The present invention also provides a web infeed device for rotary printing presses comprising an infeed element having a flexible band-shaped section and a rigid pointed nose piece connected to the flexible band section; a guide, the flexible infeed element being received in the guide; and driving elements for driving the infeed element along the guide. 
     By using a rigid pointed nose piece in conjunction with the flexible band section, excellent feeding with reduced friction can be provided. 
     The present invention also provides a web infeed device for rotary printing presses comprising an infeed element having a first flexible section, a second flexible section and a connecting piece having concave side portions connecting the first flexible section to the second flexible section; a guide, the flexible infeed element being received in the guide; and driving elements for driving the infeed element along the guide. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the present invention are described below by reference to the following drawings, in which: 
         FIG. 1  shows view of a guide according to the prior art; 
         FIG. 2  shows a cross-sectional view of the guide of  FIG. 1 ; 
         FIG. 3  shows a top view of one embodiment of an infeed element of the present invention; 
         FIG. 4  shows a perspective view of the  FIG. 3  embodiment; 
         FIG. 5  shows a side view of the  FIG. 3  embodiment; 
         FIG. 6  shows the nose piece of the  FIG. 3  embodiment; 
         FIGS. 7 and 8  show alternate embodiments of the nose piece of the infeed element; and 
         FIG. 9  shows the connecting piece of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a prior art guide  10 , similar to example to the guide shown in incorporated-by-reference U.S. Pat. No. 5,967,036. As shown in  FIG. 2 , guide  10  has a hexagonally-shaped guide area  12  with band-shaped section receiving areas  14 ,  16  extending from the sides of area  12 . 
       FIG. 3  shows a top view of one embodiment of an infeed element  50  of the present invention. Infeed element  50  includes a flexible band-shaped section  30 , for example made of metal tape, and has holes through which balls  32  pass. Infeed element  50  also includes a nose piece  20 , preferably made of a rigid material. Nose piece  20  has a tapered, in other words pointed, front  22 , and a concave side portion  24 . The rear  26  may be a spherical lobe, which can permit backward movement of the nose piece  20 . 
     As shown in  FIGS. 4 and 5  as well, a tapered front end of section  30  passes through a slit  29  in the rear  26  of nose piece  20 , and is fastened to nose piece  20  by a pin  28 . A driving element  40  is provided in a cut out in guide or track  10 . Driving element  40  has a hollow section through which the nose piece  20  and balls  32  may pass, and nips the edges of the section  30  against the guide  10  to move the flexible band-shaped section  30  and nose piece  20  in direction D. A connecting piece  60  may be provided to connect a second flexible band-shaped section  62  to section  30 . Connecting piece  60  with concave side potions also may pass through the hollow section of driving element  40 . A plurality of driving elements  40  are spaced along guide  10 . 
       FIG. 6  shows the nose piece in more detail, with a hole  21  being provided for pin  28 . Pin  28  and hole  21  may be threaded for example. Slit  29  in rear  26  may include a wider section  23 , which permits flexible band-shaped section to bend with respect to nose piece  20  when passing curves in guide  10 . 
       FIG. 7  shows an alternate embodiment of nose piece  20 . Nose piece  120  has a pointed front end  122 , concave side portions  124 , a pin hole  121  and a rear slit  129 . 
       FIG. 8  shows another alternate embodiment of nose piece  20 . Nose piece  220  has a pointed front end  222 , concave side portions  224 , a pin hole  221  and a rear slit  229 . 
       FIG. 9  shows the connecting element  60  with concave side portions  64 ,  66  and pin holes  68  and  69  for fastening the two flexible sections. 
     “Pointed” as defined herein means any tapered section, and can include a spherical or bulbous section. 
     The concave side portions of the present permit the nose piece to negotiate curves without creating excess friction, and also reduce friction during normal travel of the nose piece.