Abstract:
Signatures are transported straddling on a saddle-shaped support of a conveying device by circulating drivers and are removed by means of a blade of the conveying device and are transferred to a lift-off device. The conveying device is lowered in the region of blade and the drivers push the signatures onto the essentially fixed blade. As a result of the conveying device being lowered in the region of the blade the drivers dip down after the signatures are pushed onto the blade and no longer grip the signatures.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Priority is claimed with respect to application No. 99810669.4 filed in the European Patent Office on Jul. 26, 1999, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a conveyor for the gathering and processing of signatures, printed products and paper sheets, which terms are used interchangeably herein, which are transported by circulating drivers as they straddle a saddle-shaped support of a conveying device, are removed by means of a blade on the conveying device and transferred to a lifting device. 
     A conveyor of this type is disclosed in Swiss Application A-358 100 which is owned by the assignee herein. A lift-off blade is provided for removing the printed products from the conveying device, which blade is arranged below an elongated slot in a slide rail. An operating system periodically lifts this blade at an angle to the advancing direction,-meaning with a-vertical movement component and a movement component in an advancing direction, through the aforementioned elongated slot. The signatures are lifted off the conveyor with this movement of the lift-off blade. The signatures are folded single sheets of paper or sheets combined to form leaflets. 
     An improved conveyor of this type is shown in the Swiss Application A-525-142, also owned by the assignee herein. This system is intended to permit a higher speed. The paper sheets in this case are also lifted with a blade, which is moved periodically with a vertical component and a component oriented in advancing direction. The paper sheets lifted up with the blade are pushed between driven roller pairs that are arranged one after another. Auxiliary blades are provided in order to remove the paper sheets from the operating area of the gathering chain before the roller pairs take over. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to create a conveyor of the aforementioned type which is more simple, has a higher capacity and a more secure operation. 
     The above and other objects are accomplished according to the invention by the provision of an arrangement for gathering and processing of signatures, comprising: a conveying device including circulating drivers separated by a saddle-shaped support for transporting the signatures; and a blade arranged for removing the signatures from the conveying device so that the signatures can be transferred to a lift-off device; wherein the conveying device is lowered in a region of the blade and the drivers push the signatures onto the blade which is stationary in the conveying direction. 
     With the arrangement of the invention, it is not necessary to move the blade. The comparatively expensive movement system that was previously necessary becomes obsolete and the signatures are handled more carefully since the blade does not impact with the signatures. The drivers push the signatures onto the stationary blade. By lowering the conveyor in the region of the blade, the separate drivers are subsequently returned to a position where they no longer act upon the signatures. The conveyor according to the invention permits a continuous and very careful, but also fast transfer of the signatures from the conveyor to the blade where the signatures are respectively gripped by a lifting device. The lifting device-preferably is a rotating device, such as disclosed in European Patent 0 771 675 A which is owned by the assignee of the present application. 
     A particularly secure and careful operational transfer of the signatures to the blade is possible if, according to one modification of the invention, the blade has an upper take-up edge that is aligned with a ridgeline of the conveying device. The drivers push the signatures respectively onto this take-up edge, wherein they are not lifted up or only insignificantly and are conveyed essentially in the horizontal direction and in a straight line. 
     The signatures are lifted especially securely-off the blade if the blade is provided with at least one recess where the signatures can be gripped along the fold by a rotating lift-off device, e.g. through clamping. If, according to another modification of the invention, two recesses are arranged at a distance to each other, then the signatures can be gripped respectively at two spaced-apart locations. This permits an especially secure guidance of the signatures when they are lifted off the blade. 
     According to another modification of the invention, the conveying device is provided with a double chain and the blade intervenes between the two strands of this double chain. This is possible since the blade can have a comparably small design. 
     Based upon another modification of the invention, a horizontally extending metal sheet is arranged on the side of the conveyor as a guide for the printed products. The metal guide preferably extends into the area of the blade and guides the signatures in this area, such that they are opened up in a V-shape. The drivers in the region of the conveyor that is lowered will be moved very quickly to a position where they are outside of the effective range. A sheet-metal guide is preferably arranged on each side of the conveying device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An exemplary embodiment is explained in further detail in the following with the aid of the drawing, wherein: 
     FIG. 1 is a schematic side elevation of a conveyor according the invention; 
     FIG. 2 is a schematic end view of the conveyor in the direction of arrow II in FIG. 1; and 
     FIGS. 3 a  to  3   c  are schematic diagrams showing how the signatures are pushed onto the blade. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1, the illustrated conveyor comprises a conveying device  2  which, according to FIG. 2, contains a frame  24  that is attached to a machine frame  25 . Conveying device  2  contains an endless double chain  5 , which is wrapped around a driving sprocket  3 , reversing chain wheels  4  and  9 , as well as additional chain wheels that are not shown. According to FIG. 2, double chain  5  comprises two chain strands  5 a, which extend parallel to each other and form an intermediate space  26 . The two chain strands  5   a  respectively have a link chain  7 , as indicated in FIG. 1, with snapped-on supports  6 . 
     Thus, supports  6  move along with chain strands  5   a  and jointly form a saddle-shaped or roof-shaped support as shown in FIG.  2 . The two chain strands  5   a  operate at the same speed. In addition, drivers  8  that respectively project on the side according to FIG. 2 are fitted onto the link chains at equal distances. In FIG. 1, a signature  1 , having a two signature parts  1   b  joined at a fold  1   a , is positioned straddling on the double chain  5  and is transported between two drivers  8  from the right to the left. Drivers  8  respectively fit against signature  1  in the back and in the region of fold  1   a . Signatures  1  are placed, for example, with a feeder (not shown), onto conveying device  2  or a gathering chain installed in front. 
     The two signature parts  1   b  are guided, respectively, by fixed sheet-metal guides  11  that are mounted on a frame, such that the signatures  1  are opened respectively in a V shape, as seen in the vertical section in FIG.  2 . Sheet metal guides  11  respectively form a plane and, according to FIG. 2, a gliding surface  11   a  that is at an angle to the vertical. According to FIG. 1, the sheet metal guides  11  preferably extend essentially over the complete length of the conveying segment and, in particular, essentially extend into the region of driving sprocket  3 . The sheet metal guides  11  are fixed, as previously mentioned, and are fastened with suitable means and via frame  24  to machine frame  25 . Sheet-metal guides  11  respectively have an upper and essentially horizontally extending edge  11   b , and the saddle-shaped support extends above edge  11   b  in front of the blade and extends below the edge of the blade in a region of blade. 
     According to FIG. 1, chain wheel  9  diverts double chain  5  at a distance to driving sprocket  3 , such that a bending location B is formed in a transfer region A. In this location, a ridgeline  14 , shown with dash-dot line in FIGS. 3 a  to  3   c , changes from a horizontal region  14   a  to a slanted and descending region  14   b.    
     In transfer region A, a fixedly installed blade  13  intervenes in a gap  26  between the two chain strands  5   a . Blade  13  is a comparably small rail having an upper edge  13   b  that extends essentially in the horizontal direction. At one front end  13 a, edge  13   b  dips according to FIG. 3 a  somewhat below the horizontal region  14   a  of ridgeline  14 . The horizontal course of edge  13   b  is interrupted by two recesses  13   d , which are arranged at a distance to each other. An upward projecting guide extension  13   c  is located between the two recesses  13   d , and is designed to rise slowly, as shown, in the transporting direction and then drop sharply. 
     A lift-off device  30 , also called a guard, is arranged above blade  13  and comprises a propeller-shaped support  21  that is driven to rotate clockwise around a fixed axis  20 . The drive mechanism, for example, is a gear  17  that comprises a drive wheel  15  as well as a tensioning pulley  18  with a wrapped-around toothed belt  16 , which meshes with a wheel  19 . In a symmetrical arrangement, respectively one gripping member  22  is arranged on the support  21 , at a distance to the axis  20 , for gripping a signature  1  in the area of its fold  1   a . The gripping members  22  are provided, for example, with respectively two clamps  22   a  that are arranged at a distance to each other. The support  21  circulates at the same speed as conveying device  2 . 
     The operating mode of the conveyor is explained in the following. According to FIG. 1, endless double chain  5  is driven in the direction of arrow  12  and transports signatures  1  correspondingly from right to left. In the process, the signatures  1  are guided by support  6  as well as sheet-meta guides  11 . When a signature  1  according to FIG. 3 a  reaches transfer region A, this product is pushed by contacting driver  8  with leading edge  1   c  onto front end  13   a  of blade  13 . Approximately, at bending point B, signature  1  hits edge  13   b  with its front end  13   a  on fold  1   a . Blade  13  in this case moves with its front end  13   a  between the two parts  1   b  of signature  1 . Driver  8  then pushes signature  1  continuously onto blade  13 , until leading edge  1   c  has reached approximately the position shown in FIG. 3 b.    
     During the further transport, driver  8  that pushes the signature undergoes a vertical movement downward, owing to the deflection through double chain  5 , and finally reaches a position according to FIG. 3 c , in which it no longer engages with signature  1  and is submerged between the sheet-metal guides  11 . At that moment, signature  1  is gripped at fold la by gripping member  22  and is lifted with a clockwise rotation from blade  13 . A successively following signature  1  is at the same time pushed onto blade  13  and the above-described operation repeats itself. Lift-off device  30  supplies the gripped signature  1  to another conveying device and, as a rule, to additional processing machines, for example a cutter. 
     The invention has been described in detail with respect to preferred embodiments, and it will now be apparent from the foregoing to those skilled in the art, that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the appended claims, is intended to cover all such changes and modifications that fall within the true spirit of the invention.