JPH0367630B2 - - Google Patents

Description

[Detailed description of the invention] Industrial field of application This invention relates to a lithographic printing machine.
This invention relates to a new and improved humidifying device for use in press. Generally, the present invention relates to a new and improved continuous contact dampening device, but is not necessarily limited to one particularly useful in lithographic printing presses. More particularly, the present invention relates to a new and improved dampening system for supplying dampening liquid in a lithographic printing press with different surface speeds for the dampening roller and plate cylinder. The dampening device reduces ghosting, eliminates hickeys, reduces ink backflow into the dampening fluid, and improves print performance.

BACKGROUND OF THE INVENTION Since a lithographic offset printing plate is chemically treated, it has a printed portion and a non-printed portion, and ink adheres to the printed portion. On the other hand, the non-printed portions are hydrophilic and accept ink. To achieve the desired print, a coating of dampening liquid is applied to the surface of the plate, where the dampening liquid is retained in the hydrophilic areas (non-printed areas), but is repelled from the printed areas, and is removed from the printed areas. Printing ink adheres to the surface. However, the non-printed areas do not receive printing ink due to the ink coating. In this way, only the image of the printed portion is transferred to the blanket cylinder and then to the paper on which it is printed.

Generally, there are two types of humidifiers: contact and non-contact humidifiers. Non-contact dampening devices consist of brush and spray type devices in which there is a physical gap in the path of the dampening fluid to the plate. In such devices, ink does not flow back into the dampening fluid of the dampening device.

There are two types of contact humidifiers. namely, continuous-type devices and conventional or doctor-type devices using cloth-covered or bare foam rollers. Continuous dampening devices are generally preferred as they provide high quality printing and are relatively low maintenance since they do not require cloth or paper covered rollers.
However, a drawback of continuous humidifiers is the problem of ghosting in the printed material.

Continuous humidification devices can be classified into three groups: plate feed devices, ink roller feed devices, and combinations thereof.

In plate-fed machines, the dampening fluid is applied directly to the plate by a series of rollers independent of the inking unit. Such devices include a roller in contact with a supply of dampening fluid, which is transferred via an intermediate roller to a dampening foam roller.
The dampening foam roller rotates in contact with the plate cylinder, thereby transferring the dampening fluid. Another series of rollers, including an ink foam roller and a vibrating roller, transfers the ink to the plate cylinder.

The inking roller feed type device operates in such a way that the dampening liquid is sent to one of the rollers of the inking unit rather than to the plate. Typically, dampening fluid is directed to a first ink form roller.

A combined type of device is provided with a separate dampening foam roller, which supplies the dampening liquid to the plate. In the combined version, the dampening roller is connected to the inking device by a vibrating bridge roller. One typical example of a combination device is described in US Pat. No. 4,290,360.

Continuous ink roller feed humidifiers are widely used in the printing industry, although improvements would be desirable. One problem with ink roller feed continuous humidifiers is that the type setting of the vibrating roller relative to the first ink form roller and the type setting of the first ink form roller relative to the plate cylinder are very important. . This setting means that the first ink form roller rotates at substantially the same speed as the plate cylinder;
This is important because it is frictionally driven by a vibrating roller and a plate cylinder. In some cases, for example in sheet-fed printing machines, there is a large gap in the plate cylinder, so that when the plate cylinder rotates, the frictional contact with the vibrating roller causes the first
There is a time limit in which only the form roller is driven. This is a problem because the dampening fluid on the surface of the roller will slip, making contact and driving difficult.
Additionally, there is a slip nip between the rollers.
acts as an additional resistance that decelerates the roller.
In order to rotate the foam roller at the same speed as the vibratory roller, it is generally believed that it is necessary to maintain a relatively large profile between the vibratory roller and the first ink form roller. If this mold is not heavy enough or the plate cylinder mold is very heavy, speed changes will occur and result in poor printing. However, a heavy version of the vibrating roller is required and does not provide good ink transfer due to mechanical ghosting problems. As described herein, mechanical ghosting is the appearance of undesirable overlapping images in printed areas. A ghost is a faint image of a transfer of another printed area or of a portion of an area of the same printed area.

The cause is the same for both mechanical ghosts and relates to the principle of suppressing the transfer of ink from the inking roller to the plate in a printing press. That is, when the inking roller transfers ink to the printing plate, a symmetrical image of the printed area is formed on the inking roller. The boundaries of this symmetrical image are the areas (i) of the symmetrical image of the roller that contacts the plate and transfers the ink to the inked image areas of the plate, and the areas (i) of the symmetrical image of the roller that contacts the dampened non-image areas of the plate and transfers the ink. The line that separates the area (ii) of the symmetrical image of the ink adhering roller which receives the dampening liquid without causing any dampening.

Therefore, the ink foam roller (i.e., the one in contact with the plate cylinder) contains areas of thin ink film and little dampening fluid, and areas of thick ink film with more emulsified water, and the printing This causes undesirable overlapping images in the image.

Ink roller feed humidifiers have been widely used in the printing industry for about 10 years. One typical ink roller feed type humidifier is covered by U.S. Patent No.
It is disclosed in the specification of No. 3168037.

These devices have the advantage of requiring less maintenance, for example because the rollers do not have to be covered with cloth or paper. Due to the very fast response time when the device is put into operation, very few sheets are wasted due to wastage and fewer people are required to operate it.

In a typical ink roller feed dampening system, dampening fluid is metered into a relatively thin coating by a metering nip formed between a chrome transfer roller and a resilient metering roller. Generally, these rollers are intermeshed and driven at the same surface speed by separate variable speed motors. Since the rollers rotate at the same surface speed, the thickness of the dampening fluid film at the exit of the nip is determined by the speed of the rollers, the stiffness of the elastic rollers, the pressure between the rollers, and the viscosity of the dampening fluid. be done.

Generally, all of these factors are constant except the speed of the rollers, so the thickness of the dampening fluid at the exit of the metering nip and the feed rate of the dampening fluid will change the speed of the transfer roller and the elastic metering roller. can be changed by using a speed change controller.

A metered coating of dampening fluid advances to the nip between the first ink form roller and a transfer roller, and some of the dampening fluid is transferred from the first foam roller to the plate cylinder. The transfer roller and metering roller rotate at a slow speed and a "slip nip" is formed at the contact between the transfer roller and the first form roller.

The above-mentioned devices generally require a metering roller that is angled so that the dampening fluid feed rate is greater at the ends than at the center of the roller, except in the case of very small printing presses. I understand.
Additionally, isopropyl alcohol must be added to the dampening solution, and it has been found that this isopropyl alcohol does not clump onto the water droplets, leaving behind a thin coating.

Another problem with such devices is that when the press is driven at high speeds, the slip nip causes emulsification of the dampening fluid and ink, dispensing the ink particles back into the dampening fluid and causing the printing An effect known as tinting occurs in which non-image areas of the sheet appear as a lighter background color. One solution to that problem is the U.S. patent
It is described in the specification of No. 3937141. The solution described in this patent is to rearrange the rollers so that the slip nip moves to an ink-free position. The chrome transfer roller rotates at the same speed as the ink form roller, and the elastic metering roller also acts as a fountain roller. In this modification, the fountain pan roller is driven by a variable speed motor that controls the rate of feed of the dampening fluid. Therefore, slip nips form only where dampening fluid is present. Although this device partially solves the emulsification or ink backflow problem, it requires that the first ink form roller and transfer roller be frictionally driven, in addition to the need for an oscillating roller. When elastic rollers are used as fountain pan rollers, new maintenance problems arise.

One problem with continuous devices is ghosting. Various attempts have been made to solve the problem of ghosting that occurs in plate feed type devices.

One proposal to solve the ghosting problem is to use a separate dampening foam roller, but in this proposal the dampening foam roller is
A vibrating bridge roller is used to connect to the ink form roller.

The device has been modified in various ways. One modification was to provide a mechanism by which the vibrating bridge roller could be moved to remove the dampening device from the inking device during printing operations. Accordingly, the vibrating bridge roller can be disengaged from engagement with the dampening foam roller, reducing ghosting problems.

In summary, the prior art can generally be considered to have the following characteristics.

(i) The foam roller that supplies the dampening fluid to the plate rotates at substantially the same surface speed as the plate cylinder.

(ii) The dampening fluid feed rate is controlled by a separate motor drive mechanism that drives at least one of the dampening device rollers at a slower speed than the plate cylinder.

(iii) Initial metering of the dampening liquid onto the thin metering film is carried out by forming a metering nip between two rollers. If the printing press is wide, the roller must be beveled so that the feed rate at both ends of the roller is greater.

These prior art devices have fast response times,
Although it has gained wide acceptance in the printing industry due to reduced waste and the need for fewer skilled operators, various areas remain in need of improvement.

One problem part is that ghosting tends to occur despite conventional attempts to prevent it. Furthermore, prior art devices tend to have high construction costs, and the slip nip causes emulsification caused by backing of the ink into the dampening fluid, which results in blurring. Additionally, some prior art devices require the addition of alcohol to the dampening solution.

In the prior art, inking systems (often referred to as "Delta systems") are used to reduce the buildup of foreign particles (referred to as hickeys) on lithographic printing plates during printing. This device is also known as U.S. Patent No.
It is described in the specification of No. 3467008. What is described in this patent specification relates to a conventional device having one set of rollers for dispensing ink and another set of rollers for dispensing dampening fluid. This humidification device is not a continuous type device, but uses a normal doctor roller.

In the apparatus described in U.S. Pat. No. 3,467,008, a gear drive mechanism is attached to a first ink form roller, which is driven at a surface speed that is slower than the speed of the plate cylinder and the vibrating roller. Ru. This forms two slip nips. The two slip nips are the nip between the first ink form roller and the plate cylinder and the nip between the first ink form roller and the vibrating roller. The wiping action occurs at a slip nip adjacent to the plate cylinder, and the wiping action removes the hitkey from the plate cylinder. The removed hitkeys are carried along the ink path and collected on a lidar roll or in an ink sump. This equipment has been found to substantially increase productivity and improve ink adhesion, particularly in solid areas.

The device described in the aforementioned US patent has limitations. One is that the provision of a gear drive mechanism for the ink form roller increases construction costs to some extent. Another limitation is the need for a relatively powerful drive mechanism for the inking roller and the need for a helical gear mechanism to eliminate gear irregularities.

Furthermore, the device described in US Pat. No. 3,467,008 has hitherto been used only in conventional inking and dampening devices. This is because it was considered necessary to rotate the dampening foam roller at the same speed as the plate cylinder. If the dampening foam roller was not rotated at the same speed as the plate cylinder, there was a risk that halftones would be blurred or edges of solid portions would be blurred.

Another problem arises when using a bridging roller that rotates at the same speed as the dampening foam roller, which causes ink emulsification and ghosting.

Problems to be Solved by the Invention In view of the above, an object of the present invention is to provide a new and improved humidifier.

Another object of the invention is to provide a new and improved humidifier with improved performance.

Another object of the invention is to provide a new and improved humidification device that is inexpensive to manufacture.

Still another object of the present invention is to provide a new and improved continuous lithographic moistening device that is substantially free from ghosting.

It is an object of this invention to provide a new and improved humidifier having an inexpensive drive mechanism.

Yet another object of the present invention is to provide a new and improved humidification device that easily and quickly removes substantially foreign particles and/or dust.

Another object of the present invention is to provide a new and improved dampening device in which foreign matter and/or hits are removed and ghosting is substantially reduced due to the different surface velocities of the dampening roller and plate cylinder. There is a particular thing.

Yet another object of the invention is to provide a new and improved dampening device for a lithographic printing press in which a dampening roller and a plate cylinder rotate at different surface speeds to remove foreign particles and/or hitskies. There is a particular thing.

Another object of the invention is to provide a new and improved dampening device that prevents ink from returning to the dampening solution.

Another object of the invention is to provide a new and improved dampening device which has a wiping action to remove foreign particles by including a dampening roller having a surface velocity different from that of the plate cylinder.

Another object of the invention is to provide a new and improved method for use in a lithographic printing press to improve print quality by reducing ghosting.

Another object of the invention is to provide a new and improved method for use in a continuous contact lithographic printing press in which a dampening fluid is supplied to reduce foreign particles and substantially reduce ghosting. be.

Another object of the invention is to provide a contact continuous type having a plate cylinder and a dampening roller, the plate cylinder and the dampening roller rotating at different surface speeds to produce a wiping action to remove foreign particles from the plate cylinder. The object of the present invention is to provide a new and improved method for use in a lithographic printing press.

Yet another object of the invention is to provide a novel and novel method for preventing ink emulsification and ghosting caused by such emulsification by using an ink receiving roller in contact with and rotating at the same speed as the dampening roller. An object of the present invention is to provide an improved humidification device.

Additional objects and advantages of the present invention will be set forth in the following description, and the extent to which it will become apparent from the description below. That is, the objects and advantages will be realized and attained by the instruments, components, features, devices, steps, and procedures particularly pointed out in the claims.

Briefly, the present invention is directed to a new and improved humidifier. More particularly, in a preferred embodiment, the invention relates to an improvement for a continuous dampening device in which the speed of the roller carrying the dampening liquid is different from the speed of the plate cylinder.
In a preferred embodiment, the speed of the dampening roller is slower than the speed of the plate cylinder.

Generally speaking, the present invention includes a dampening foam roller, a dampening fluid transfer roller, and a conventional metering mechanism for metering dampening fluid. The dampening form roller can be conveniently coupled to a drive mechanism for a lithographic printing press, with the dampening form roller rotating at a constant speed that is slower than the speed of the plate cylinder, so that foreign objects and (or) a wiping action occurs that removes the hitki;
This allows foreign objects and debris to be removed. An unexpected advantage of the present invention is that ghosting, which is typically a problem with continuous devices, is virtually absent.

The first dampening foam roller may be gear driven by a gear connection with the chrome transfer roller at a speed intermediate that of the transfer roller and the plate cylinder.

In another embodiment, the ink receiving roller is in surface engagement with the dampening roller and rotates at the same speed as the dampening roller to prevent ink emulsification and ghosting caused by the emulsification.

Embodiments Embodiments of the present invention will be described below based on the drawings.

In FIG. 1a, a means and method for removing foreign particles from a lithographic printing press is generally shown, as detailed in U.S. Pat. No. 3,467,008. Such devices are referred to herein as "delta" devices.

As shown, a rotating flat plate cylinder 2 is shown rotating in a counterclockwise direction by conventional means (not shown).

In the inking apparatus shown in FIG. 1a, there is shown an ink foam roller 4, a dampening foam roller 6, a vibrating roller 7, and a pan roller 8 rotating in a reservoir 10 containing dampening fluid. The doctor roller 12 moves from the position where it engages with the pan roller 8 to the position indicated by the dash-dotted line where the dampening foam roller 6 can transfer the dampening liquid received from the vibrating roller 7 to the rotary cylinder 2. At the point of contact with the plate cylinder, the ink form roller 4 moves in the same direction as the plate cylinder, but its surface speed is lower than that of the plate cylinder. The slip nip is the position marked with an "S". This device has been found to substantially remove foreign particles known as hitkies, improving so-called commercial ink laydowns.

In that device, roller 4 is part of the inking system and serves to remove hitches.

Figure 1b shows various U.S. patents, e.g.
No. 3168037, No. 3259062, No. 3343484 and No.
3937141 is a schematic diagram of a prior art humidification device disclosed in the specification of No. 3937141; Such a humidification device includes a plate cylinder 14 that engages a first ink form roller 16, which in turn engages a chrome pan roller 18, which in turn engages in a sump 17. Rotate with. A metering roller 20 is provided for metering the dampening liquid. The measuring roller 20 is the pan roller 18
is driven by the separation drive motor and controller 19 while in engagement with the metering roller 20;
Rotate the pan roller 18. In this device, foreign particles (hitskies) cause printing problems.

Another prior art dampening type mechanism is schematically illustrated in FIG. 1C.

The device includes a rotating plate cylinder 22, a first ink form roller 24, and a dampening form roller 26. Optionally, a roller 24 is provided between the first ink form roller 24 and the dampening roller 26.
A bridge roller 32 may be provided which engages the and 26. Pan roller 28 rotates within dampening fluid reservoir 29 and engages dampening foam 26 and metering roller 30. The metering roller is driven by a separate drive motor and controller (not shown).

FIG. 2 schematically shows a continuous ink roller feed type humidifier according to a first embodiment of the present invention.

According to the invention, a humidifying device is provided in which ghosts are substantially eliminated and dust and other foreign matter are removed.

As shown in the example, this humidifying device has a rotating plate cylinder 36 that rotates in a counterclockwise direction.

The rotating plate cylinder 36 engages a first ink form roller 38 which rotates in the opposite direction to the plate cylinder, ie, in a clockwise direction. In this way, the surfaces of the rotating plate cylinder and the first ink form roller move in the same direction at their contact position. The dampening device according to the invention has a dampening fluid reservoir 40 in which a chrome pan roller 42 is immersed. Chrome pan roller 42 is rotationally engaged with elastic metering roller 44. Preferably, the elastic metering roller is covered with rubber. A separate drive motor and controller for the metering roller is provided. A metering roller meters the coating of dampening solution.

Metering roller 44 engages chrome pan roller 42, which in turn contacts first ink form roller 38. The ink form roller moves in the opposite direction at the point of contact with the plate cylinder and rotates at a slower surface speed than the plate cylinder. This difference in speed creates a wiping action between the plate cylinder 36 and the first ink form roller 38, thereby reducing and removing debris, known as hitskies, that accumulate in the ink area of the plate cylinder.

FIG. 3 shows another embodiment of the invention known as a continuous plate feed humidifier.

This device is equipped with an ink separating device and a humidifying device. As shown in the figure, a plate cylinder 46 and an ink foam roller 48 that rotates in contact with a vibrating roller 51 are provided.
The dampening fluid supply roller 50 is in contact with a dampening roller 52 which is in turn in contact with a metering roller 54 .

In this embodiment, the dampening solution supply roller 50 is driven at a lower surface speed than the contact portion of the plate cylinder 46 with the roller 50, thereby creating a wiping action that reduces foreign particles and allows their removal.

This device has the advantage that hitkeys are removed. Furthermore, since one of the rollers in contact with the dampening fluid supply roller 50 is covered only with dampening fluid, the power required to drive the dampening fluid supply roller 50 may be extremely small.

FIG. 4 schematically shows another embodiment of the invention. This embodiment of the invention relates to a combination modification of the invention. This embodiment includes a plate cylinder 64, a dampening foam roller 66, and a pan roller 68 rotating within a sump 70.
is provided. Furthermore, a first ink form roller 72 and a bridging roller 74 between the first ink form roller and the dampening form roller are provided. A conventional metering roller 76 can also be used to meter the dampening fluid.

A common feature for all embodiments of the invention is that the dampening fluid supply roller supplies dampening fluid to the plate cylinder and rotates at a different surface speed than the plate cylinder (preferably at a slower speed than the plate cylinder). It is. In such a device, foreign particles are reduced and eventually removed, ghosting is substantially reduced, power consumption is lower, and there is less ink backflow into the dampening fluid.

Although the present invention provides means to prevent excessive ink emulsification, such means may cause ghosting in certain situations. Thus, for example, if an ink receiving roller is used that engages a dampening foam roller and rotates at a slower speed than the plate cylinder, ghosting will occur. If the ink receiving roller rotates at the same speed as the plate cylinder, excessive ink emulsification will occur.

As shown, the means include an ink receiving roller which can also act as a bridge roller. The ink receiving roller is in contact with the dampening roller and rotates at the same speed as the dampening roller.

Although the embodiment of FIGS. 2-4 represents a substantial improvement over prior art examples, excessive ink emulsification and significant ghosting may occur in certain situations. Accordingly, the embodiments of FIGS. 2, 3, and 4 have been modified as shown in FIGS. 5, 6, and 7, respectively.

These modified examples of Figures 5, 6, and 7 are the same as those shown in Figures 2, 3, and 4, and include the same descriptions except as stated below. Yes, they have the same number.

In FIG. 5, ink receiving roller 39 is in contact with dampening roller 38 and rotates by conventional means (not shown) at the same surface speed as the dampening roller. This can be accomplished in any convenient manner known in the art, such as by meshing gears between the dampening roller 38 and the ink receiving roller 39.

FIG. 6 is an embodiment of the invention similar to FIG.
An ink receiving roller 49 is in contact with a dampening roller 50. The ink receiving roller 49 rotates at the same surface speed as the dampening roller by conventional means (not shown) well known in the art.

FIG. 7 shows a modification of the device shown in FIG.
In this modification, a bridge roller 74 is shown. The change in this variation is that the bridging roller 74 in contact with the dampening roller 66 rotates at the same speed as the dampening roller. Fifth
As with the embodiment of FIGS. and 6, such a device can prevent excessive ghosting and ink emulsification.

As explained above, according to the present invention, the pan rollers 42, 52, 68 rotate within the dampening fluid reservoirs 40, 70, the rotating dampening rollers 38, 50, 66 continuously contact the pan rollers, and the rotating Contact with plate cylinders 36, 46, 64. Dampening fluid is thus transferred from the dampening fluid reservoir to the rotating dampening roller and the plate cylinder. The plate cylinder and rotating dampening roller then rotate at different surface speeds. A wiping action therefore occurs between the plate cylinder and the rotating dampening roller, and foreign matter can be removed from the plate cylinder by the rotating dampening roller. Further, according to the invention, the ink receiving rollers 39, 49, 74 are in surface contact with the rotating dampening roller, and the ink receiving roller and the plate cylinder rotate at different surface speeds. This makes it possible to control ink emulsification and reduce ghosting.

[Brief explanation of drawings]

1a, 1b, and 1c are schematic diagrams showing an example of a conventional humidifying device, FIG. 2 is a schematic diagram of a humidifying device according to an embodiment of the present invention, and FIG. 3 is a schematic diagram showing an example of a conventional humidifying device. FIG. 4 is a schematic diagram of a dampening device according to another embodiment of the invention; FIG. 5 is a schematic diagram of a dampening device according to another embodiment of the invention; FIG.
FIG. 6 is a schematic view of a dampening device of another embodiment of the invention similar to FIG. A general view of the humidifying device, FIG.
FIG. 3 is a schematic view of a humidifier according to another embodiment of the invention similar to the figure; 36, 46, 64... plate cylinder, 38,
48, 72... Ink form roller, 39, 4
9,74...Ink receiving roller, 40,70...
Water reservoir, 42, 52, 68...Pan roller, 44, 5
4, 76... Measuring roller, 50, 66... Dampening foam roller, 51... Vibrating roller, 74... Bridge roller.

Claims (1)

Claims: 1. In a continuous contact lithographic printing press having an ink supply system in continuous contact with a dampening system and for continuously delivering ink and dampening liquid to a rotating plate cylinder, said plate cylinder is rotated. Apparatus for dampening a rotary plate cylinder of a lithographic printing press of the type having drive means for rotating other rollers of the lithographic printing press, comprising: (a) a dampening fluid reservoir; (b) said a pan roller rotating within a dampening fluid reservoir; (c) metering means cooperating with said pan roller for measuring the thickness of said dampening fluid; (d) in continuous contact with said pan roller and configured to control said rotation. a rotating dampening roller in contact with the plate cylinder and receiving dampening liquid metered onto the surface, whereby the dampening liquid is transferred from the dampening liquid reservoir to the rotating dampening roller and the plate cylinder; (e) an ink-receiving roller and means for mounting said ink-receiving roller in surface contact with said rotating dampening roller; (f) said drive means being transmission connected to said plate cylinder; , said drive means being transmission connected to said rotary dampening roller to rotate it; (g) comprising means for removing foreign matter from said plate cylinder by said rotary dampening roller;
the means comprising means in said drive means for rotating said plate cylinder and said rotating dampening roller at different surface speeds to produce a wiping action between said plate cylinder and said rotating dampening roller; (h) means for controlling ink emulsification and reducing ghosting, the means comprising: an ink-receiving roller in contact with the rotating dampening roller, and rotating the ink-receiving roller and the plate cylinder at different surface speeds. and a means in the driving means for lithographic printing press. 2. The apparatus of claim 1, wherein the rotating dampening roller and the ink receiving roller rotate at the same speed. 3. The apparatus of claim 1, wherein said rotating dampening roller and said ink receiving roller have a lower surface velocity than said plate cylinder. 4. Apparatus according to claim 3, wherein the dampening system is of the ink feed type. 5. Apparatus according to claim 3, wherein the dampening system is of the plate feed type. 6. Apparatus according to claim 3, wherein the dampening system is of a combined type. 7 A device for delivering dampening liquid to a rotating plate cylinder of a lithographic printing press, thereby removing hitches and preventing ghosting, comprising: (a) a dampening liquid reservoir; and (b) a dampening liquid reservoir. (c) metering means cooperating with said pan roller for metering the thickness of said dampening fluid; and (d) metering means in contact with said rotating plate cylinder for metering the thickness of said dampening fluid on a surface thereof. a rotating dampening roller for receiving dampening solution, thereby transmitting the dampening solution from the dampening solution reservoir to the rotating dampening roller and the plate cylinder; Transmission connected to the plate cylinder,
drive means for said lithographic printing press for rotating said rotary plate cylinder at a first surface speed; (f) said drive means being transmission connected to said rotary dampening roller to rotate said dampening roller at said first surface speed; are rotated at different second surface speeds, thereby creating a wiping action between the rotary plate cylinder and the rotary dampening roller to remove hit keys. . 8. The apparatus of claim 7, wherein the rotating dampening roller has a lower surface velocity than the rotating plate cylinder. 9. A method according to claim 8, wherein the dampening system is of the ink feed type. 10. Apparatus according to claim 8, wherein the dampening system is of the plate feed type. 11. The apparatus of claim 8, wherein the dampening system is of a combined type.