DE1761085A1 - Printing press - Google Patents

Description

The invention relates to planographic printing machines and, in particular, to a method using printing cylinders, in which the printing is carried out directly from a «printing fora sheet to a printer. pienblatt is transferred without wiping a rubber cylinder. In principle, these direct printing duplicating machines should have certain advantages, since cleaning is required between the insertion of the individual printing form sheets of the blanket cylinder is no longer required, which

109116/0046

p »MwHw UdH, CHpt-Whteck-teq. Α »» »Hemmonn, DieL-Hiy». MINCHIN 3, TtHHHIHSTIA SSI II ^ T ^ M wit "« « -i

PATgNTANWAU BI. HtNHOtD SCHMIOT

indicates that a delay between the individual work processes is avoided. _{/; v}

However, there are considerable problems with direct printing, since a certain elasticity is required on the printing surface in order to achieve a sufficient transfer of the image. The use of an elastic, usually not regulating wetness; cleaned surface in the back area raises problems, as color can precipitate. This means that there are traces of color on the printing cylinder, which prevent that the size of the copy sheets is changed. The build-up of paint can even prevent it from feeding of the copy sheets is done with sufficient accuracy. If, however, the elastic surface is cleaned regularly, then one of the essential advantages of the direct printing process is negated or at least substantially impaired.

It has been found according to the present invention that in an unusual combination and arrangement of the Cylinder is avoided that paint can deposit] this means that the machine for longer periods of time can be put into operation without interruption.

100818/0046 - 3 -

BAD OWiGINAL

Order the printing forms in the case of duplication processes made of cheap sheets of paper with a flat printing covering on one side, with printing forms of the type mentioned, a few hundred copies are made, after which the printing forms be thrown away.

The present invention is intended to provide a device and a procedure should be created to avoid cheap, exchangeable * to produce high-quality copies using the direct printing process, which can be compared with those using the offset process manufactured are comparable. Any delay in the operational process should be avoided. It should also be avoided that the operator of the machine is responsible for the offset process performs any cleaning work required between replacing the print forms.

According to the present invention, an elastic covering λ is used on the printing forme cylinder below the printing forme instead of pulling the printing forme onto a rigid printing forme cylinder in the known manner. The conditions required for the printing process are created with the aid of this elastic covering, which is arranged below the printing form. A printing cylinder with a rigid upper

109816/0046

BATH ORIGINAL

assigned area, whereby the copy sheets in pressure contact with the artwork bsw. can get with the printing form. Since it is rigid, the printing cylinder can have a surface a strongly water-binding, color-restoring material, like B.B. Chrome, while the normally elastic material is uniformly ink-absorbing. PUr the Overlapping edge areas of the printing form, therefore, make it impossible to prevent ink deposition on the printing cylinder of the copy sheet edges. This in turn means that on the back of a wider copy sheet there is no Color imprint arises or that so much color accumulates that the contact εwipe the cylinders over their entire Length is affected.

The invention is explained with reference to the accompanying drawings.

FIG. 1 is a schematic side view of a flat printing filling device which is based on the feature the present invention works;

Fig. 2 is a side view, on an enlarged scale, of one printing forme cylinder a used in the device according to FIG. 1; and

109816/0046 _ ₅ _

BAD OWGLAL

Pig. 3 is a plan view of the printing forme and impression cylinders of the device according to FIG. 1 from line 3-3 in FIG. 1.

In Fig. 1 of the drawings, a duplicating machine 10 is shown schematically. This has a printing forme cylinder 12 with an elastic surface \ k . On this surface there is a planographic printing form 16 with an image 17 on it. With the help of a train of orphans 18, paint and moisture are applied to the printing form. The Walζenlug ends in an inking unit 20 and in a dampening unit 22. The printing phone sheet 16 is preferably exchangeable and covered, as shown in FIGS. 2 and 3 can be seen, the elastic cal surface 14 to prevent contact of the surface with the inking rollers.

A printing cylinder 2k cooperates with the printing forme cylinder. Copy sheets 26 are fed to this from a supply 28. After the copy sheets have been passed through the rollers 12, 2k , the data are transported into a receptacle 30.

The printing fore cylinder 12 is shown in detail in FIG. The elastic surface 14 consists of a strip

109616/0046

BATH ORIGINAL

fen of rubber, which is drawn and clamped on the surface of the cylinder. The exchangeable printing form 16 is located above the elastic layer and is clamped to this with its edges. This is done by clamping bodies or gripping bodies 32 in a conventional manner.

The cylinders 12 and 2k can be engaged by gearwheels for a common drive and can be set in rotation by a conventional drive. This drive is not shown since it is not required for understanding the present invention.

While the cylinders rotate during a backing process, the image 17 on the printing form sheet 6 is supplied with color, while moisture is applied to the background of the printing form sheet. The color of the image is transferred to the copy sheet 26 at the gap between the cylinders 12, Zk, so that the desired copy is obtained in a known manner.

Usually the printing form 16 is always slightly wider than the copy sheet 26 (Fig. 3). This avoids having the sharp edges of the printing form a small amount of ink and thereby create unwanted marginal lines on the copy sheet. Of course, the desired

109616/0046

Gebnie can also be achieved if the printing form and the Copy sheets are exactly the same width. A control of the copy sheet feeding with the desired accuracy however, it is usually not feasible.

The present invention is based on the recognition of the fact that significant amounts of paint are produced by the Background of the print form can be included. These There is usually not enough paint, ™ to be visible on the copy sheets. Still is a very fine precipitate of paint is present, which is deposited with each bar. In the areas of the printing cylinder, which extend over the copy sheet and come to lie under the edge areas of the printing form (i.e.

the areas χ, χ in Fig. 3) this color film will be on map the printing cylinder.

Investigations on the basis of known methods, namely M attaching the printing form to a rigid printing form cylinder with an elastically supported surface for transfer, have shown that the known elastic transfer surfaces are ink-absorbing, so that ink accumulates in the areas χ, χ. These accumulations of color are deposited on wider copy sheets if these are narrower after the passage

109816/0046 " ⁸ "

BATH ORIGINAL

Copy sheets are used. The color will also settle on the edges of copy sheets of equal width, if any lateral displacement · takes place. This color scheme can be thick enough to interfere with proper feeding and printing of the copy sheets as long as the color is not has been removed or wiped off.

■ | The problem mentioned can be solved in a very simple and direct manner, while the arrangement is made such that the elastic transfer surface is completely covered by the printing form sheet, after which the printing form is arranged opposite a fixed or rigid printing cylinder. The surface of the rigid printing cylinder "" can now be coated in such a way that an ink-repellent surface is arranged in the Berelohen χ, χ. Any water-binding, ink-repellent coating material can be used for this purpose. The surface of the printing cylinder 2k is preferably coated with chrome.

With the described arrangement, it has been found that a flat printing machine operating asi direct printing can be used for an unlimited period of time without the cylinder being cleaned gen to have to. This is how you get a machine

109816/0046

1761985

greater usability and greater efficiency, because one of the main problems, which is the use of an operator and the interruption of the machine required was overcome.

106616/0046

Claims (2)

PATENT CLAIMS! Drucknaaohin · sur making copies ie direct druok, with an imprint on one side of a · copying sheet · is produced, with a printing cylinder, a printing cylinder for copy sheets, which are more echnal than those with printing forms that come into contact with the copy sheets, and with a device to color and moisturize one on the surface of the printing forme cylinder Apply a drub sheet, characterized in that the printing cylinder (12) an elastic cover (1%> is provided, which can be used continuously with a number of interchangeable printing forms that the Bela « lies under each printout form and carries it, 109816/0046 BATH ■ -χ- whereby the elastic covering is covered by each printing form in such a way that it faces the ink application device is slotted that the surface of the printing cylinder is rigid, and that a hydrophilic and highly ink-repellent layer is provided on the printing cylinder, whereby the elastic layer (i4) of the printing forme cylinder opposite a contact with the ink application device receiving the ink is slit, and that the printing cylinder in _ ■ the areas in which the printing form overlaps the copy sheets, resists an accumulation of ink, whereby a Long, continuous use of the printing machine is guaranteed without having to clean it from time to time. 2. Printing machine according to claim 1, characterized in that that the surface of the pressure cylinder (24) consists of chrome. 3 Process for the production of planographic copies, thereby ' marked that a) on a printing fora cylinder of a planographic printing machine Covering made of a «elastic material that is pulled up b) «in exchangeable, exposed printing form sheet is applied to the printing form cylinder in such a way that this completely covers the surface of the printing form cylinder and this ^BATH protects against color, and that the printing forme cylinder is set in rotation, and c) that I will wear ink and moisture on the surface of the printing forme cylinder while it rotates, and d) that a printing cylinder with a rigid printing surface of the Printing forme cylinder is assigned, wherein e) the printing cylinder has a surface made of a rigid, non-flexible covering which is hydrophilic and strong is color-repellent, and f) that one after the other copy sheets on the impression cylinder are arranged, which are narrower than the printing formes used on the printing form cylinder »where each each of the copy sheets comes into pressure contact with a printing form sheet located on the printing form cylinder when the printing cylinder is rotated, until the desired number of Copies were printed that the printing form is removed from the elastic surface of the printing form cylinder, and that the process steps b), c) and f) are repeated with a number of exchangeable, exposed printing form sheets without having to clean any of the cylinders. 1Q9P * / 0 (H6 BATH ORIGINAL