Sheet guide cylinder

Sheet Guide Cylinder

The invention relates to a further development of a sheet guide cylinder described in the German main patent No. 42 23 839. This sheet guide cylinder known from said main patent is particularly used, for example, in a chain delivery of a sheet-fed rotary printing press, wherein the sheet guide cylinder directly follows an impression cylinder. Therein, the sheet guide cylinder is located between two chain wheels which are concentric with its axis of rotation and have a pair of endless delivery chains wound around them. The delivery chains carry and convey gripper systems, and the sheets coming from the impression cylinder are clamped by the gripper systems and conveyed out of the area of the impression cylinder to a sheet piling device. Thereby, it is the task of the sheet guide cylinde'r to guide a respective sheet clamped by a gripper system along the conveying path defined by the chain wheels in such a manner that the print quality of a freshly printed surface is not diminished by so-called smudging while it faces the sheet guide cylinder.

Therefore, the above mentioned known sheet guide cylinder is provided with an air cushion for supporting the respective sheet and keeping it away from the outer cylindrical surface of the sheet guide cylinder during operation. This air cushion is created by means of a stream of air emerging from a vane ring. The vanes of the vane ring have a curved profile. Thus, it can be expected of the above mentioned known sheet guide cylinder that with a design of the curves of the vane profile being advantageous to the air flow-line, a favorable relationship between the power supplied to the drive of the vane ring on the one hand and the kinetic energy inherent in the stream of air stream emerging from the vane ring on the other hand can be achieved. Such an optimization

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- 2 of air flow, however, does not generally ensure that a respective sheet is securely kept from the outer cylindrical surface of the sheet guide cylinder. Operational conditions may arise which have an opposite effect, namely, that a sheet is pressed against the outer cylindrical surface of the sheet guide cylinder as a result of a reduced static pressure created around the sheet and cylinder due to the air stream emerging from the vane ring. Such operational conditions can be caused, for example, by a change of mechanical properties of the sheets and by a change of velocity of the sheets which deviates from the production speed.

It, therefore, is the object of the invention to improve the sheet guide cylinder known from the above mentioned German patent in such a way that the sheets are not pressed against the outer cylindrical surface of the sheet guide cylinder, when operating conditions change. The solution to this object is a sheet guide cylinder as stated in the appended patent claim.

With the operational use of a sheet guide cylinder in accordance with the present invention, the air stream for creating said air cushion, in the section of the air stream where it impacts on the respective sheet, occupies a substantially greater radial proportion, as compared to the known sheet guide cylinder. This has the effect, that a stable operation is ensured in the sense that a respective sheet is kept away from the outer cylindrical surface of the sheet guide cylinder, even if a change of an operational condition corresponding to the above mentioned examples has occurred. An additional advantage lies in the fact that especially at the vane ring within the cylinder housing loss of air flow can be reduced to a minimum through a suitable structure of the vane profile, without regard for the directional proportions of the air stream leaving the vane ring. The design of the skeleton forming the outer ’96 1001 3B

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cylindrical surface of the cylinder can likewise be of the kind to minimize loss of air flow at the guiding vanes. Thus, with a sheet guide cylinder according to the invention a stable operation in the sense described above can be achieved without having to spend much additional energy for the drive of the air stream-producing vane ring.

The features of the present invention will become apparent to those skilled in the art upon reading the following description of a preferred embodiment in view of the accompanying drawings, wherein

Fig. 1 is a schematic illustration of a sheet guide cylinder integrated with a chain delivery of a sheet-fed rotary printing press in accordance with the invention;

Fig. 2 is a cross-section along the axis of rotation of a sheet guide cylinder in accordance with the invention ;

Fig. 3 is a section of the cylinder housing of a sheet guide cylinder in accordance with the invention.

The section of·a sheet-fed rotary printing press shown in Fig. 1 is a schematic illustration of an impression cylinder 1 and a successive section of a chain delivery 2.

The chain delivery 2 comprises a first chain wheel 5 associated with a first side wall 3 and a second chain wheel 6 associated with a second side wall 4. The chain wheels 5 and 6 are turnable with respect to the axis of rotation 7 (see Fig. 2) of a sheet guide cylinder 8 arranged between them, and a pair of endless delivery chains 9, 10 is wound around them. The delivery chains 9, 10 carry and convey gripper systems 11, and the sheets coming from the impression cylinder 1 are clamped by the gripper systems and

- 4 conveyed out of the area of the impression cylinder 1 to a sheet piling device (not shown). The mentioned sheets are not shown for reasons of clarity.

As can be seen in Figs. 2 and 3, the sheet guide cylinder 8 has a cylinder housing which comprises face parts 13 and 14 provided with openings 12 and an outer cylindrical surface 15 in the form of a skeleton surrounding the axis of rotation 7. A respective axle section 16, 17, which is concentric with the axis of rotation 7, is fixedly connected with a respective face part 13, 14, said axle sections 16, 17 being respectively mounted in the first and second side walls 3 and 4 so as to be rotatable with respect to the axis of rotation 7. Furthermore, a respective chain wheel 5, 6 is fixedly connected with a respective axle section 16, 17. The operational rotation of the cylinder housing around the axis of rotation 7 takes place by means of a first rotary drive member 18 in the form of a gear wheel which, in the illustrated exemplary embodiment, is fixedly connected with the axle section 16. This gear wheel, representing a first rotary drive member 18, can in known manner be part of a gear wheel train of the sheet-fed rotary printing press, which is connected with a drive aggregate; and in accordance with the exemplary embodiment described herein, the sheet guide cylinder 8 and the chain wheels 5 and 6, together, are turned around the axis of rotation 7 by means of said gear wheel train, when in operation.

As can further be seen in Figs. 1 and 2, there is provided a vane ring 19 within the cylinder housing, said vane ring 19 being concentric with the axis of rotation 7 and being rotatable with respect to said axis of rotation 7 relative to said cylinder housing. The vane ring is formed with vanes 20, 20' which extend longitudinally of the sheet guide cylinder 8 and have a curved vane profile in planes perpendicular to the axis of rotation 7.

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- 5 In the illustrated exemplary embodiment shown in Fig. 2, the interconnection of the vane ring 19 has been realized as follows: a respective vane 20, 20' extends longitudinally of the sheet guide cylinder 8 from a first vane end facing a respective face part 13, 14 to a second vane end located approximately in the longitudinal center of the sheet guide cylinder 8. The respective first vane ends are fastened to a respective ring 21 being concentric with the axis of rotation 7, and the respective second vane ends are fastened to a circular disk 22 being also concentric with the axis of rotation 7.

The rotary ability of the vane ring 19 with respect to the axis of rotation 7 relative to the cylinder housing has been realized in the exemplary embodiment as follows: A drive shaft 23 being concentric with the axis of rotation 7 is rotatably mounted at its ends in a respective one of the axle sections 16 and 17, and further is fixedly connected with the circular disk 22.

For the operational rotation of the vane ring 19 there is provided a second rotary drive member 25 which is illustrated in the exemplary embodiment as a stub shaft of a preferably controllable motor 24 mounted in the second side wall 4, said rotary drive member 25 being connected with one end of the drive shaft 23 by means of a coupling 26.

In order to achieve a smooth operation of the vane ring 19 while rotating relative to the cylinder housing, as shown in the exemplary embodiment, a respective ring 21 supported on a respective bearing ring 27 is braced against the cylinder housing. Thereby, a respective one of the bearing rings 27 embraces an inlet pipe 28, said inlet pipe 28, being concentric with the axis of rotation 7, is fastened to a respective face part 13, 14 and extends into the interior of

- 6 the cylinder housing. As a matter of choice, such a bearing could be dispensed with.

The stream of air generated by the rotation of the vane ring 19 flows through the openings 12 provided in the face parts 13 and 14 and reaches the inside of the outer cylindrical surface 15, then, it passes a suction area 29 which is surrounded by the vane ring 19 and extends longitudinally of the sheet guide cylinder 8. In the exemplary embodiment this suction area 29 is divided by the circular disk 22 into two suction areas 29’, 29'', which are respectively connected, via an inlet pipe 28, with the openings 12 of a respective one of the face parts 13, 14.

Fig. 3 shows, in accordance with the invention, an embodiment of the outer cylindrical surface 15 of the sheet guide cylinder 8 in the form of a skeleton using guide vanes 30. Here, a portion of the skeleton is formed with traverses 31 which connect the first face part 13 with the second face part 14 not shown in Fig. 3, whereas a respective side part 13, 14 is essentially formed as a disk and has a circumferential surface 32 like an outer cylindrical surface, and the traverses 31 are distributed over the circumference of this disk. A frame 33 is inserted in a respective space formed between neighboring traverses 31 and connected with a respective side part 13, 14. A respective frame 33 essentially consists of a thin-walled, hollow cylindrical segment provided with recesses 34, said frame 33 extending from the first face part 13 to the second face part 14 and being curved in a manner that a respective end part 35 of said frame 33 associated with a respective face part 13, 14 adapts to the respective circumferential surface 32 of said face parts 13, 14. The recesses 34 extend longitudinally of the outer cylindrical surface 15 from the first end part 35 to the second end part 35 (not shown in Fig. 3) of the frame 33 and are delimited from one another by means of ο 1001 3Β bars 36 extending in circumferential direction of said hollow cylinder segment, with a respective recess 34 extending in circumferential direction of the outer cylindrical surface 15 from a first frame piece 37 to a second frame piece 37', said frame pieces 37 and 37', in turn, extending longitudinally of the outer cylindrical surface 15 from said first to said second end part 35 of said frame 33, thus, forming a respective end section of said hollow cylinder segment in circumferential direction of the outer cylindrical surface 15.

The guide vanes 30 forming a further portion of the skeleton are now inserted into the recesses 34 of the entirety of the frames 33 arranged between neighboring traverses 31. The guide vanes 30 extend from a first to a second end part 35 of the respective frame 33 and, thus, longitudinally of the sheet guide cylinder 8. In the planes perpendicular to the axis of rotation 7 a respective guide vane 30 has a guide vane profile. In the illustrated embodiment a respective guide vane profile extends from an imagined first outer cylindrical surface being inside of the entirety of said hollow cylinder segments and symmetric with the axis of rotation 7 to an imagined second outer cylindrical surface being outside of the entirety of said hollow cylinder segments and symmetric with the axis of rotation 7, the imagined second outer cylindrical surface representing an envelope surface surrounding the outer cylindrical surface 15. The guide vane profile and the position of the guide vanes 30 relativ to a respective frame 33 are chosen to the effect that a respective outer profile section of the guide vane profile lying outside of the entirety of the hollow cylinder segments ends essentially radially in said envelope surface. The remaining portion of the guide vane profile is preferably curved to such a degree that an inner profile section of the guide vane profile facing away from

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the outer profile section tends to point against the rotating direction of the vane ring 19.

In the exemplary embodiment of the invention illustrated herein the guide vanes 30, in the area of the end parts 35 of the frame 33 and the bars 36, are provided with releases which are put on said end parts 35 and bars 36. A mutual fixation of guide vanes 30 on the one hand and frame 33 on the other hand can take place by welding, provided that suitable manufacturing material had been used. By way of such mutual fixation the skeleton parts consisting of respective guide vanes 30 and a respective frame 33 are formed as shown in Fig. 3, these skeleton parts being connectable with a respective face part 13, 14 by means of a screw connection at the circumferential surface 32 of said respective face part 13, 14.

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LIST OF REFERENCE NUMERALS

9

19

20, 20'

29', 29’’ impression cylinder chain delivery first side wall second side wall first chain wheel second chain wheel axis of rotation sheet guide cylinder endless delivery chain endless delivery chain gripper systems openings of the face parts 13, 14 face part of cylinder housing face part of cylinder housing outer cylindrical surface axle section axle section first rotary drive member vane ring vanes of the vane ring 19 ring circular disk drive shaft motor second rotary drive member coupling bearing ring for ring 21 inlet pipe sectional suction area guide vanes traverses circumferential surface of face parts!3, 14

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37, frame recess end part of frame 33 37’ frame piece