DK148965B - Machine for repairing damaged paper sheets - Google Patents

Description

148965 i

The present invention relates to a machine for repairing damaged sheets of paper and of the kind specified in the preamble of claim 1.

5 Various types of such machines are known to be used for repairing historical sheets of paper, where major or minor parts of the sheet have been lost due to animal or microorganism attacks, fire or mechanical damage, and all of which have the following common features in the working form: 10 A number of damaged sheets are placed on a fine screen. The sieve is placed on a coarse grid structure in a container arrangement. A metered amount of water containing a predetermined amount of finely suspended paper fibers is fed to the top of the sheets on the screen. The sheets, meanwhile, are retained on the sieve by another coarse grid structure or the like. The water is now sucked or flowed through the seas, the water flow almost exclusively in the damaged areas where the seas are naked. This leaves the suspended paper fibers in the damaged areas where new paper is thus cast. After appropriate finishing (pressing, drying, gluing), the repaired sheet will appear as new, full-edged paper with significantly improved resistance to further degradation.

The method of operation described is rather time-consuming, as the calculation of the required amount of fiber requires a measurement of the size of the damaged areas in each case. Furthermore, the handling of the rather large volumes of water requires considerable time.

If the water is recycled, which is possible, each filling process often requires two pumping sequences, with water and fibers usually mixed in a special mixing vessel before being fed to the top of the screen, also by pumping.

A further disadvantage is the following: As the flow resistance of the damaged portions grows abruptly during filling, it is inevitable that a small amount of water will eventually be sucked directly through the original paper material, leaving its paper content as a usually quite thin paper film in areas, where this is not desired.

2 148965

It is the object of the invention to eliminate these disadvantages. This is accomplished by the initial design of the machine 5 as defined in the characterizing part of claim 1. In this way, the filling is achieved continuously for a continuous flow of damaged sheets of paper, whereby the speed of filling can be increased 5 to 10 times over that obtainable with known machines. The machine has a slow-moving conveyor belt, made of 10 fine-mesh sieve material, in the paper language known as a wire.

On a short section of the upper side of the wire, this mite is guided by two rollers running on the wire and supporting the two transverse walls of an underlying suction box between two side walls which are arranged along the wire on each side. On the particular piece of the wire, this is supported by a coarse grating, which forms a lid in the suction box. From the suction box, via a pipe, there is a connection to a main reservoir, which is placed under the suction box. Above the wire, limited by the rollers across the wire and the sidewalls along the wire, a bath consisting of a thin suspension of paper fibers in water is maintained on the order of 0.1 grams of paper fibers (dry matter). liters of water.

As the paper fibers are all trapped on the wire, the water flows through the wire, down the suction box and down into the main reservoir.

In cases where the wire is sealed by trapped paper fibers, there is a strong pressure difference between the top and bottom of the wire, equivalent in size to the height of the water column from the surface of the reservoir to the surface of the bath. This pressure difference is utilized to compress the fibers and increase the entanglement and retain the precipitated fibers on the wire.

30 As water flows into the reservoir, a corresponding amount of water is constantly inflated from the reservoir to the bath, so that an approximately constant water depth is maintained in the bath, which is controlled by a swimmer in the bath.

Along with the water being pumped from the reservoir, the bath is supplied with new fiber material from a highly placed concentrated fiber suspension container, usually 1 to 2 grams of fiber solids. liters of water. The concentrated fiber suspension is supplied via a tube which opens near the suction nozzle of the pump which performs the pumping from the reservoir to the bath. Thus, a quantity of fiber is constantly inflated which is approximately proportional to the amount of water pumped, irrespective of its size. The damaged sheets are placed on the top of the wire as it moves toward the first roll. The sheets are carried by the wire under the roll 10 and under the bath, where the constantly flowing fiber suspension leaves its paper content in the damaged areas. The very low dust density and large constant depth of the bath ensures that all damage is covered completely with fibers.

Any naked wire party, e.g. resulting from an injury which enters the bath immediately causes a very large stream of water; the damage is almost immediately closed by the remaining fibers, after which the water level in the bath is restored by the pump operating for a maximum of a short period of time. During the remainder of the injury, a weak flow of water passes through it, thereby slightly increasing the thickness of the fiber layer. The final thickness is a function of the maximum pressure difference over the wire, the paper-fiber density in the bath, the passage time, and the composition and physical condition of the fibers, but is essentially independent of the area of damage. Therefore, a desired layer thickness can be set by means of the aforementioned parameters, of which the fiber density in the bath is preferred.

It is found to be sufficient to provide a constant fiber concentration to ensure a satisfactory constant layer thickness in a wide range of damage sizes because the manner in which the paper fibers are fed to the bath has a highly smoothing effect.

Since normally new bare areas of the wire are always available to the water stream, undesirable deposits of fibers are never seen on undamaged portions of the sheets. Contributing to this is also the short time the sheets are in the bath.

In order to ensure a reasonable watertightness of the bath, the rollers without physical shafts can rest freely on the wire, while in the longitudinal direction of the wire they are controlled by smaller support rollers. Water escaping at the roll ends and under the rollers is fed into the reservoir 5.

To prevent the damaged sheets from sticking to the rollers, these can be coated with fabric stockings which are further treated with a release agent in the form of e.g. polytetrafluoræthylenspray.

10 is a vertical section through an embodiment of the machine according to the invention.

The machine consists of a finely masked wire 1, which runs over three running rollers 2, a tension roller 3 and is driven by a drive roller 4. The direction of movement is as indicated by arrows along the wire.

15 The upper part of the wire passes a suction box 5, the lid of which is a carrier grid 6. Above the suction box, a bath 7 is maintained in a room.

The space is limited partly by two rollers marked 8 and partly by two side walls 9. The rollers rest on the wire and create tightness against the upper side of the suction box and are held in the longitudinal direction of the machine by 20 every four short support rollers 10.

The depth of the bath is maintained by a float 12, which controls the capacity of a pump 13 immersed in the reservoir 11. Said components are carried by a rack not shown.

Constant supply of new fiber material takes place from a storage tank marked 14.

The damaged sheets are placed on the upper part of the wire to the left of the drawing and filled in the bath between the rollers.

When the filled sheets leave the bath during the last roll, they pass another suction box where they are dried by being sucked in with air, then removed from the wire and then treated with pressure, further drying and gluing.