DE2259085A1 - INK UNIT FOR FLAT PRINTING MACHINES - Google Patents

Description

PATENT LAWYERS

DR.-ING. BY KREISLER DR.-ING. SCHÖNWALD DR.-ING.TH. MEYER DR. FUES DIPL-CHEM. ALEK VON KREISLER DIPL.-CHEM. CAROLA KELLER DR.-ING. KLÖPSCH DIPL-ING. SELTING

COLOGNE 1, DEICHMANNHALJS

Dec. 1, 197? Sg-Ax / ls

VICKERS -LIMITED, Vickers House, Millbank Tower, Millbank, London SWl / England

'' Inking unit for flat printing machines

The invention relates to an inking unit for printing machines, especially for planographic printing machines.

In the flat printing process, an ink roller is used for the application of the color used on a plate cylinder, the one wetted printing form with printing areas (or image areas) that have a water-repellent and ink-absorbing effect, and non-printing (or non-image) areas that are water-retaining and ink-repellent. Just the image areas thus take on the printing color. The color is transferred from the image areas of the printing form to the The material to be printed or, in the case of offset printing, is transferred to a rubber blanket, which in turn produces the color transfers to the material to be printed. The transfer of the color from the inking roller only to the image areas the printing forme has the consequence that one does not

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transferred ink "negative image" of the image areas remains on the inking roller. In Cases in which a large proportion of the surface of the printing form consists of image-free areas the remaining "negative image" on the inking roller is quite considerable. If no action to remove this "negative image" and to replace this "negative image" with a uniform color film are taken on the inking roller, the "negative image" can be an uneven coloration of the Cause image areas.

Attempts have been made to create the "negative image" by using several ink rollers to apply the ink to the Apply the plate cylinder and, by axially reciprocating some rollers, apply the ink to the Transfer ink rollers, eliminate them. An attempt was also made to pass the "negative image" on the inking roller Increasing the pressure between the inking roller and another roller that feeds the inking roller, to eliminate. However, if the inking roller is made of an elastic material, this is the mode of operation unsatisfactory.

The object of the invention is to produce a thin, uniform ink film on the ink roller, which is suitable for application to the printing form and to accomplish this without disturbance by the "negative image".

In conventional printing machines with an inking roller, the receives the color from a paint box, the

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flow of dye to the inking roller in general Adjustment of the color box in many places over. regulated its width. This attitude is something laborious. It is also due to the large number of rollers in the inking unit on these printing machines not easily possible, rapid changes in the thickness of the ink film to be applied to the ink roller to undertake.

The invention has the further object of making an inking unit available that the need for setting the ink fountain over the entire width of the printing machine switches off, and that a fast one Adjustment of the thickness of what is applied to the inking roller (and thus to the printing form of the plate cylinder) -Color film enables.

The inking unit according to the invention for applying printing ink to a plate cylinder on the one Flat printing form is clamped is characterized by ■.

a) an ink roller to apply the ink. on the plate cylinder,

b) an inking roller (ductor) which ■ applies an ink film to the inking roller,. .,

c) an ink knife which, together with the inking roller, forms the ink fountain,

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d) a doctor roller arranged in contact with the inking roller and opposite to the direction of rotation of the ink roller at the contact line of these rollers rotates, the color of the Inking roller takes over and thereby the thickness of what is left on the inking roller and regulates the color film to be transferred to the plate cylinder,

e) a member for removing ink from the squeegee roller and.

r ■ ■

f) a mechanism for driving the stripping roller at a peripheral speed, which, relative to the peripheral speed, can be changed to the thickness of the inking roller To change the ink roller remaining ink film.

The inking roller or the ductor can rotate in a conventional ink fountain, but it can preferably with the help of a suitable gear drive at a much higher speed than a normal one, be rotated with ratchet driven ductor. If the inking unit is used in conjunction with a low-speed press is to be used, the ductor can be made with approximately the same circumference speed like the inking roller. In the case of high-speed presses, however, the ductor must move with a lower peripheral speed than the inking roller

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Turn to take enough color from the paint box and to use energy economically reach. The drive mechanism for the ductor is preferably designed so that the relative Circumferential speeds of the ductor and the inking roller can be changed, but in general it is it is not necessary to change the relative speed during printing, if a suitable one Relative speed has been chosen once.

The ductor rotates continuously while pressing, picks up a relatively thick, even ink film from the ink fountain and transfers it to the ink roller. The thickness of the in this way The ink film applied to the ink roller depends on the relative circumferential speeds of the ductor and the inking roller.- The thickness of the ink film on the inking roller is determined by adjusting the speed of rotation the stripper roller (which is in constant contact with the inking roller). The from the inking roller transferred to the squeegee roller excess ink is from the squeegee roller, for example wise removed with a conventional scraper and advantageously returned to the paint fountain from which the ductor takes the paint. The inking roller covered with a film of paint of the required thickness that goes through the squeegee roller is determined, is covered, then transfers this color to the color-absorbing image areas the printing forme of the plate cylinder with the result that a "negative image", which shows the non-image areas of the Corresponds to the printing form on which the inking roller is formed. The "negative image" on the inking roller then mixes

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with the relatively thick ink film, which is transferred to the ink roller with the ductor, and becomes effective destroyed. The thickness of the color layer created on the inking roller is then determined by the stripping roller regulated.

In one embodiment of the invention, there is Inking unit from the three rollers, namely the inking roller, the inking roller or the ductor and the stripping roller. In this case the ductor is in contact with the inking roller and these rollers rotate on theirs Point of contact in the same direction. For an effective and economical exploitation, the Inking roller stripped off excess paint should be returned to the paint box, as this paint is normally used is stripped in an amount greater than that used for the actual printing. This can be done by placing a doctor blade in such a position above the doctor roller, that it can return the excess ink from the squeegee roller to the ink fountain. With the three-roller system In this embodiment, this can be useful in the case of a downward-moving plate cylinder ^ surface can be achieved by the doctor roller is arranged above the ductor so that the doctor blade the squeegee roller is located above the ink fountain. In this case, the paint box can be attached to the Outside of the machine can be placed in an accessible location. However, if the inking unit is on a to be arranged upwardly moving surface of the plate cylinder is a certain modification necessary. In the event of a possible modification

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tion becomes both the paint fountain and the scraper roller placed under the inking roller and a doctor blade attached over the doctor roller so that excess Paint is removed and immediately returned to the paint box. In this case where the Inking roller against an ascending plate cylinder surface runs, the downward moving surface of the ductor in a three-roll system of the inside of the Machine facing, and this presupposes that the paint box feeding the paint down also is arranged on the inside of the machine. However, this arrangement has the disadvantage, among other things, that access to the paint box is restricted. This means that the observation of the stand or the The amount of paint, the pouring in and smoothing of the paint in the paint box become more difficult. This difficulty can be remedied according to a further embodiment of the invention by in the inking between the ductor and the inking roller an intermediate roller is included, which the direction of rotation of the ductor reverses. The intermediate roller causes the ductor and the inking roller to both rotate either clockwise or counterclockwise. Through this it is possible to arrange a paint fountain, feeding the paint downwards, towards the outside of the machine. In this case the device for removing the ink from the squeegee roller (e.g. a doctor blade) and the paint box on opposite sides of the ductor, but the one from this one Device removed from the squeegee roller through the gap between the intermediate roller and the ductor and via a device that removes the ink from the

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Intermediate roller removed, returned to the ink fountain It should be noted that it is necessary that any given part of the inking roller be behind the doctor roller the intermediate roller and in front of the plate cylinder touches, so that only a color film with a set thickness the Printing form reached.

If necessary, a control roller can be included in the inking unit according to the invention, which consists of a There is an electrically conductive material and acts on the inking roller so that it is part of it Ink film decreases, the thickness of which has been adjusted by the doctor roller. A color film measuring device according to an earlier suggestion by the applicant can then be used to determine the thickness of the film of the color on the control roller and thus to give a measure of the thickness of the color film is applied to the plate cylinder.

In addition, a device for measuring the amount of water on the printing form in the inking unit according to the invention be included. This device can be used in the manner of the moisture measuring device, the object of the German patent (patent application P 22 36 7IO.8) of the applicant is formed will.

Optionally, one or more rollers, e.g. the inking roller, the possibly existing control roller ' ze and / or preferably the wiper roller are moved axially back and forth to the thickness of the ink films to design more evenly and also the wear

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balance.

If necessary, an additional roller can be in contact with the inking roller in the inking unit, 'after this has touched the plate cylinder, to remove flakes and dust from the print Remove any material, e.g. paper, that has got onto the inking roller. This additional roller can be in itself known way with leather or another similar Be related to the material.

By suitable choice of the relative rotational speeds the ink feed roller (ductor) and the inking roller at the start of printing (these relative speeds are preferred during printing kept constant) and by adjusting the relative Circumferential speeds of the inking roller and the stripping roller while printing it is possible to move onto the inking roller and from there onto the plate cylinder to regulate the amount of paint applied. For example, the device for applying the paint can the ductor can be set so that the ductor the printing ink as a uniform film with a thickness of receives about 250 to 750 ^ u. Appropriate setting The circumferential speed of the ductor will then put a certain amount of paint on the ductor (if necessary over the intermediate roller) to the inking roller, on which an ink film with a thickness of two

for example about 100 tu is formed. At the slit cyrischgn the inking roller and the squeegee roller becomes one Part of the color depending on the relative viewing speeds the inking roller and the squeegee roller

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removed, so that on the ink roller the ink in the thickness required for planographic printing, for example about 5 to 20 / u remains.

The invention is described in detail below in conjunction with the drawings for better understanding described, the embodiments of the invention show:

Fig. 1 shows schematically a vertical section through a printing machine with an inking unit according to a Embodiment of the invention. .

FIG. 2 shows, schematically and in perspective, the printing press shown in FIG. 1.

Fig. 3 is a graph showing the change the thickness of the ink film on the inking roller of the inking unit shown in Fig. 1 and in Fig. 2 in Dependence on the relative speeds of the doctor roller and the inking roller illustrated.

Fig. H shows schematically as a vertical section a printing press with another embodiment of the inking unit according to the invention.

Fig. 5 shows; schematically and in perspective the in FLg. ¹ I illustrated printing machine.

The inking units shown in Fig. 1 and 2 have a single inking roller 1 that applies the color to the downward ;; running surface of a, plate cylinder 2

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applies, on which a plateau form is stretched. The plate cylinder 2 is rotated about its axis 2a by a motor 12 via a connecting member, which is shown schematically indicated by the line 13, driven. The plate cylinder 2 drives the inking roller 1 around its Axis la via a gear drive, which is not shown for the sake of clarity. The plate cylinder 2 is in contact with a blanket cylinder 3. The machine is also equipped with a printing cylinder 4 provided. The inking roller is rubber coated. The inking unit also includes a cast-iron ink feed roller (or ductor) 5 / who is in contact with the inking roller 1 -and is on the line of contact: these rollers rotate in the same direction as the inking roller 1. A color knife 6 lies against it the duct 5 * that a paint box is formed, which receives the printing ink 7. The ductor 5 is driven around its axis 5a by the motor 12 via a gear transmission, which is shown schematically and denoted by the reference numeral 14, and a connecting rod, which is indicated schematically by the line 15 is driven. The gear transmission l4 rotates the ductor 5 at a variable peripheral speed, which is so low that "sticking" of the paint in the paint fountain during operation is avoided. This speed is generally slower than the speed of the inking roller. A color box of this one Art is relatively simple and compared to an ink box formed by two rollers ... cheap and made in such a way that a sufficient supply of paint for the order on the operation Duktor 5 is always available. Furthermore 'the ends of the paint box can be relatively "easily in Ub-

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Licher way to seal. The inking unit also includes a cast iron stripping roller 8, which is arranged above the ductor. The stripping roller 8 runs in contact with the inking roller 1 and rotates in the opposite direction to the inking roller 1 at their points of contact. The stripping roller 8 can be driven independently of the inking roller by a motor 16 at a variable speed via an intermediate member, which is shown schematically by the line 17. A doctor blade 9 is arranged in contact with the doctor roller 8 above the ink fountain. All rollers 1 to h, 5 and 8 have parallel axes of rotation, and their direction of rotation is indicated by the arrows. Rollers 1, 5 and 8 have the same diameter, but this is not essential, provided that their speeds of rotation and the speed of rotation of roll 11 are chosen so that the required peripheral speeds are obtained. Rollers 2, J5 and 4 have essentially the same diameter (apart from roll J>, which is slightly smaller so that the soft rubber blanket really rolls against the harder rolls 2 and h ). These rollers have a larger diameter than the inking roller 1. The transmission ratio of the gear transmission between rollers 1 and 2 is set so that these rollers have the same peripheral speeds.

While the button is pressed, the ink knife 6 is set so that that a uniform, relatively thick film of the color (e.g. about 500 ρ thick) on the Surface of the duct 5 is formed. The ductor rotates at a peripheral speed of, for example a quarter of the peripheral speed

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of the inking roller 1, whereby a considerable amount of the ink on the ductor 5 is taken up by the inking roller 1, on which an ink film is formed with a thickness of, for example, 100 n . At the gap between the inking roller 1 and the stripping roller 8, most of this color on the inking roller 1 is removed by the stripping roller 8 depending on the relative peripheral speeds of the inking roller 1 and the stripping roller 8. The paint is removed from the stripping roller 8 with the stripping knife 9. This color falls back into the mass of the color 7, which is located in the paint box that is formed by the ductor 5 and the paint knife 6. The amount of ink that remains on the inking roller 1 after it has touched the stripping roller 8 thus depends on the relative peripheral speeds of the inking roller 1 and the stripping roller 8. In this connection, reference is made to FIG by changing the relative speeds of the doctor roller 8 and the inking roller 1. The thickness of the film of the paint (in jü.) _r that remains on the inking roller 1 after this the

Has touched stripping roller 8 is the ordinate and the ratio of the speed of the stripping roller to The speed of the inking roller is plotted as the abscissa. The graph shows two curves. the Curve A represents the case where the inking roller rotates at 53 rpm. Curve B represents the case in FIG the inking roller rotates at 210 rpm (1 m / sec). The curves show that with increasing rotational speed of the squeegee roller relative to the 'speed of rotation of the inking roller back on the inking roller -

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remaining amount of paint is less and vice versa. By appropriately changing the speed of the drive motor 16 for the stripping roller 8, it remains open the paint roller returns the paint as a film with a thickness of, for example, 5 Μ.

The ink remaining as a film on the ink roller after contact with the stripping roller 8 is transferred to the image areas of the printing form on the plate cylinder 2. This has the consequence that a "negative image" of these image areas remains on the inking roller 1. The thickness of the ink which forms this "negative image" is generally less than the thickness of the ink film after the inking roller contacts the doctor roller. It is, for example, 2 / u, but is sufficient to produce ghost images in conventional systems. At the gap between the inking roller 1 and the roller 5, the "negative image" goes under in the relatively thick (for example about 100 yes) ink film that is transferred from the roller 5 to the inking roller 1. The resulting ink film on the ink roller 1 thus has a substantially uniform thickness over its entire width regardless of the image that is being printed, so that the need to change the settings of the ink knife across the width of the printing machine is eliminated. Rather thick film of paint on the paint roller

1 is then regulated by the stripping roller 8, where: through a new, even, thin film of color regardless of the shape of the "negative image" on the Inking roller after touching the plate cylinder

2 is formed. It is obvious that while

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a comparatively large amount of ink from the ink fountain to the inking roller 1 to the stripping roller 8 during operation and circulates back into the paint box, leaving a new, even thin film of paint that is no "Negative image" has, the plate cylinder is constantly presented. By regulating the peripheral speed the stripping roller 8 relative to the peripheral speed of the inking roller 1 is an ink film of Controlled thickness on the inking roller 1 is formed. The "negative image" on the inking roller 1 after you touch it with the plate cylinder 2 goes under in the circulating main flow of the color, and a completely new one Film is produced with every revolution of the inking roller 1. By switching off the "negative image" eliminated the need for multiple actuators on the ink fountain across the width of the platen. Since the thickness of the ink layer is only at one gap, i.e. at the gap between the ink roller 1 and the stripping roller 8 is set, the thickness of the plate cylinder 2 coming into contact with it Ink film on the ink roller 1 can be changed as quickly as the speed of the stripping roller 8 can be changed. The time it takes for the amount of paint supplied to change is noticeable on the printed material, is thus reduced to a minimum. When hiring the machine, the rotational speed of the roller 5 is controlled so that a film of sufficient Thickness on the inking roller 1 is formed. Thereafter, the speed of rotation of the ductor 5 can be kept constant will.

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The ink picked up by the image locations of the plate cylinder 2 is transferred to the blanket cylinder 3 and from there to the paper 10 to be printed, which runs around the impression cylinder 4. All rollers 1, 2, 3 and ¹ J rotate at a peripheral speed which corresponds to the surface speed of the paper 10.

If desired, a copper control roller 1 in the inking unit are included. This control roller comes into contact with the inking roller 1 and rotates at its point of contact with this roller in the same direction as the inking roller 1. The control roller picks up paint from inking roller 1, and the thickness of the film of paint on the control roller is then measured, for example with the aid of a device (not shown), such as the object an earlier proposal by the applicant. This is a measure of the thickness of the color film on the Inking roller 1, before it touches the plate cylinder 2, received.

When the machine is running at high speed, the work involved in shearing the films can become the printing ink is expended, a significant increase in temperature cause. Therefore, a device for cooling the paint is preferably included. This device may be in the form of cooling water passages in the bottom of the ink knife 6 or a system for circulating cooling water through one of the rollers 5 # 8 and 11 or through all of these rollers.

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The invention will now be further described in connection with Figo 4 and Fig. 5, in which parts corresponding to parts shown in Fig. 1 and Fig. 2 ,, denoted by the same Bezügsziffern ¹ are show "Figure" 4 and "a Inking unit according to the invention for inking the upward running surface of a driven plate cylinder. As with the embodiment shown in FIG _o 1 and Fig. 2, the plate cylinder 2, which carries the Flaehdruckform runs in contact with the blanket cylinder 3 · Further, the impression cylinder 4 is part of the machine. The inking unit comprises a rubber-covered, inking roller 1 for the order of the color on the plate cylinder 2 and a · driven ductor -5-a-us ^! Metal that supplies the ink to the inking roller 1 via an intermediate roller 21 which is in constant contact with the printing roller and advantageously has the same peripheral speed as the ductor 5. The inking roller 1 is driven by the plate cylinder 2 via a gear drive (which has been omitted for the sake of clarity) so that the surface speeds of the inking roller 1 and the plate cylinder 2 are the same and the inking roller 1 and the plate cylinder 2 are in the same direction at their point of contact turn. In the manner described in connection with FIGS. 1 and 2, the paint knife 6 lies against the ductor 5, forming a paint box which contains the paint 7.

As in the embodiment described above an independently driven stripping roller belongs to the inking unit 8 driven by a motor 16 with variable Rotation counting is driven. The squeegee roller 8

Ί ..

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runs in contact with the inking roller 1 and rotates in the opposite direction to this at the point of contact of this Rollers. The inking unit also comprises a doctor blade 9 which lies against the doctor roller 8. The Ductor

However, 5 and the doctor roller 8 are under the inking roller 1, and an additional doctor blade 22 is arranged adjacent to the intermediate roller 21 so that it has a distance of about 0.25 mm from this roller.

In principle, the inking unit works in this embodiment in the same way as the inking unit shown in FIGS. 1 and 2. In operation, the color knife

6 adjusted so that a uniform, relatively thick film of the paint (for example about 500 u) is formed on the surface of the ductor 5. This color is transferred to the intermediate roller 21. The intermediate roller 21 and the ductor 5 rotate at a peripheral speed which is generally less than the peripheral speed of the inking roller (e.g. at about a quarter of the peripheral speed of the inking roller), whereby a substantial amount of the ink on the intermediate roller 21 is taken up by the inking roller 1 and an ink film of, for example, 100 / µ thick is formed on the ink roller 1. As in the embodiment described above, most of the ink on the inking roller 1 is removed by the stripping roller 8 as a function of the relative peripheral speeds of these rollers. For example, the color remains in a film thickness of, for example, 5M on the inking roller 1, and this color is applied to the image areas of the printing form and from there over the rubber blanket Λ

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The surface of the paper IO running around the impression cylinder 4 is transferred. (The rollers 1, 2, 5 and h rotate at a peripheral speed which corresponds to the surface speed of the paper.) The "negative image" remaining on the ink roller is absorbed in the relatively thick ink film the intermediate roller 21 and is effectively destroyed is already on the ductor 5, through the gap between the ductor 5 and the intermediate roller 21. A part of the ink film thus formed is then removed from the intermediate roller 21 by the doctor blade 22, falls onto the ductor 5 and is thereby returned to the paint box. The remainder of the ink film is transported by the intermediate roller 21 past the doctor blade 22 and applied to the ink roller 1. The doctor blade 22 serves to limit the thickness of the ink layer on the intermediate roller 21. In this way, a continuously increasing thickness of the film of the ink in the roller group is prevented.

FIGS. H and 5 show that the inking unit enables the inking of an ascending surface of the plate cylinder, while the ink fountain can be arranged at an accessible location on the outside of the printing machine.

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Claims (9)

Expectations 1.J inking unit for applying printing ink to a plate cylinder, who carries a planographic printing form, g e k e η η draws through a) an ink roller (1) for applying ink to the plate cylinder (2), b) an ink feed roller or a ductor (5) for applying an ink film to the ink roller (1), c) a paint knife (6) which forms a paint box with the ductor (5), d) a stripping roller (8) which is arranged in contact with the inking roller (1) itself in the opposite direction to the direction of rotation of the inking roller (1) at the point of contact of these rollers turns. Color from the inking roller (1) decreases and thereby the thickness of the on the plate cylinder (2) regulates the ink film to be applied and remaining on the ink roller (1), e) a device (9) for removing ink from the stripping roller (8) and f) a drive (16) that controls the stripping roller (8) drives at a peripheral speed relative to the peripheral speed of the inking roller (1) Can be changed to match the 30982B / 0325 - 21 - Thickness of the on egg roller (1) ver ~ to change the permanent film of color, 2. Inking unit according to claim 1, further characterized by a device (9) to return the. from the squeegee roller (8) removed into the ink fountain. 5 · Inking unit according to claim 1 or 2, d a d u r c h marked that the ductor (5) is arranged in contact with the inking roller (1), ■ rotates in the same direction as the inking roller (1) at the point of contact between these rollers - - and thereby transfers ink from the ink fountain to the ink roller (1). * - 4. Inking unit according to claims 1 to J >> characterized in that the stripping roller (8) is arranged above the ductor (5) and has a stripping knife (9) for the removal of ink from the stripping roller (8) and for the return of the Color is provided in the color box. 5. Inking unit according to claim 1 or 2, characterized by an intermediate roller (21), which is arranged between the ductor (5) and the inking roller (1) so that the ductor (5) and the inking roller (1) both clockwise or counterclockwise. turn clockwise, which removes' color from Duktor (5) 'over the intermediate roller (21) onto the inking roller (1) is transmitted « 3098 25/032 5 - 22 - 6. Inking unit according to claim 5 »marked thereby indicates that a single intermediate roller (21) is arranged in contact with the diaphragm (5), also rotates in the same direction as the ductor (5) at the point of contact of these rollers is in contact with the inking roller (1) and is mounted so that it moves in the same direction like the inking roller (1) on its contact parts turns. 7. Inking unit according to claims 1 to 6, characterized marked that a) the stripping roller (8) is provided with a stripping knife (9), the color of the The stripping roller (8) is removed and placed on the ductor (5), and b) a doctor blade is arranged adjacent to the intermediate roller (21) and part of the Returns the ink on the intermediate roller to the ink fountain. 8. Inking unit according to claims 1 to 7, characterized marked that the inking roller (1) is an elastic roller. 9. Planographic printing machine, characterized by an inking unit according to claims 1 to 309825/0325