DE29617889U1 - Feed table for sheets in the feeder of a sheet printing machine - Google Patents

Description

tosaur . 1 _ " ·· ·· A-1796

11.10.96

Sheet feeder table in the feeder of a sheet-fed printing press

The innovation relates to a feed table for sheets in the feeder of a sheet-fed printing machine with design features according to protection claim 1.

Such a design corresponds to the state of the art generally practiced by various manufacturers of such feeders. When the sheets fed to the feeder from a stack are separated, large amounts of air are blown under the sheets. In particular, sheets made of lighter paper or other lighter printing materials tend to become wavy and lie accordingly wavy on the feed table. This can cause poor feed registration when aligning the sheets or duplication phenomena.

As a countermeasure, the excess air is discharged downwards through openings in the table plate with a cross-section that is tailored to the amount of air. Round, oval and elongated holes are well known in the top view. Corners or edges of sheets can get caught in the holes during sheet transport and lead to serious consequences for the continuation of the printing operation.

The innovation is therefore based on the task of preventing the sheets from snagging by changing the openings in the table plate.

This problem is solved by the innovation through the features of claim 1.

By creating bevels in the area of the openings, the so-called "paper tripping" at the edges of the openings is prevented. The openings are preferably formed by punch cuts and subsequent moldings that are pressed downwards from the table top. It is advantageous if each

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Formation has a slope which encloses an angle α of less than 45 degrees with the transport plane formed by the table surface.

Examples of the innovation are shown in the drawing. Shown are:

5
Figure 1 is a schematic representation of a sheet feeder in section,

Figure 2 shows a vertical longitudinal section parallel to the sheet transport through a table plate,

Figure 3 is a schematic plan view of a table plate according to Figure 1 with several opening variants,

Figure 4 shows a longitudinal section corresponding to Figure 1 through a further embodiment and

Figure 5 is a plan view of an opening corresponding to Figure 4.

A table plate 1 of a feeder 2 has a number of openings 3 with a length L through which the air blown under the sheet 4 during sheet separation can flow downwards. In the case of the embodiment according to Figure 2, the openings 3 are formed by round or curved incisions 5 running approximately transversely to the sheet conveying direction, as can be seen from the graphic representation in Figure 3. In the direction of the sheet travel, the incisions 5 are followed by a formation 6 pressed downwards out of the table plate 1. Different geometries of such formations 6 are shown in Figure 3. Accordingly, the opening 3 with the formation 6 can form an air guide body that converges, diverges or is parallel to the incision 5.

In the embodiments in Figures 4 and 5, the opening 3 is funnel-shaped in

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designed in such a way that a funnel-shaped punching inlet 7 inclined relative to the normal to the table surface in the direction of sheet transport is effectively used to solve the problem mentioned.

The table plate 1 can be made of steel or another metallic material and, if necessary, also of plastic.

The formations 6 and the punching inlet 7 each have a slope 8, which

the sheet transport plane formed by the surface of the table plate 1 forms an angle α that is smaller than 45 degrees. A length L of the opening 3 is divided into a section length L ₁ of the opening 3 projected onto the surface of the table plate 1 in the area of the continuous opening and a length L ₂ in the area of the bevels 8. The length L ₁ is smaller than a height H between the bevel 8 and the table plate 1. This measure prevents the sheet 4 to be transported from reaching under the free edge of the bevel 8 with its edges or corners. A section length L ₂ of the bevel 8 is many times greater than a thickness D of the table plate 1.

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LIST OF REFERENCE SYMBOLS

1 Table sheet 2 Investors 3 opening 4 arc 5 incision 6 Forming 7 Punch feed 8th Slope &agr; angle L Length (3) _L1 Length (H) L: Length (8) H Height (3) D Table sheet thickness

Claims (7)

c** tosaur _5- '* ··■ &Agr;-1796 CLAIMS 1. Feed table for sheets in the feeder of a sheet processing machine, the table surface of which has through openings at least in partial areas, via which the sheets separated by a suction head are transported against marks for sheet alignment and through whose openings the air introduced under the sheets in the area of the suction head flows downwards, characterized in that the openings (3) have a slope (8) on the table surface. 2. Feed table according to claim 1, characterized in that the openings (3) are punched into sheet metal plates (1) and have a slope (8) on the table surface introduced by material deformation. 3. Feed table according to claim 1, characterized in that the slope (8) is a formation (6) pressed downwards out of the sheet metal plate (1). 4. Feed table according to one of the preceding claims, characterized in that the slope (8) encloses an angle (α) with the sheet transport plane. 5. Feed table according to one of the preceding claims, characterized in that the angle (α) is less than 45 degrees. tosaur -&ogr;'-""""·*··''&mgr; ⁵⁵ .- ⁵ A-1796 6. Feed table according to one of the preceding claims, characterized in that a section length (L) of the opening (3) is smaller than a height (H) of the slopes. 7. Feed table according to one of the preceding claims, characterized in that a length (L ₂ ) of the slopes (8) is many times greater than a thickness (D) of the table plate (1).