US3411441A - Brush-type moistening mechanism - Google Patents

Description

NOV. 19, 1968 c, HERMAcH ET AL 3,411,441

BRUSH-TYPE MOISTENING MECHANISM Filed June 24, 1966 4 Sheets-Sheet. l

NVENTOR CARL J. HERMACH,R|HARD GJ A LOUIS DEPA Nov. 19, 1968 c, J, HERM'ACH ET AL 3,411,441

BRUSH-TYPE MOI STENING MECHANISM Filed June 24, 1966 4 Sheets-Sheet 2 [NVENTOQS CAQL J. HERM cH RICHARD G. KARCH Lou/s S.DEPA

Nov. 19, 1968 c. J. HERMACH ET AL 3,411,441

BRUSH-TYPE MOISTENING MECHANISM Filed June 24, 1966 4 Sheets-Sheet 5 INVENTORS CARL J. HERMACH RICHARD G. KARcH Lows S. DEPA a #77 r vs.

Nov. 19, 1968 c. J. HERMACH ET AL 3,411,441

BRUSH-TYPE MOISTENING MECHANISM Filed June 24. 1966 v 4 Sheets-Sheet 4 INVENTORS CARL J. HERMACH RICHARD G. KARCH Laws 5. DEPA 3 01% Ar'rvs.

United States Patent 3,411,441 BRUSH-TYPE MOISTENING MECHANISM Carl J. Hermach, Westchester, Richard G. Karch, Hillside,

and Louis S. Depa, Harwood Heights, Ill., assignors to Miehle-Gross-Dexter, Incorporated, Chicago, 111., a corporation of Delaware Filed June 24, 1966, Ser. No. 560,264 2 Claims. (Cl. 101-148) ABSTRACT OF THE DISCLOSURE A dampening device for a lithograph press having a brush cylinder, flicking blade, blade mounting, and hydrophilic roller constructed and arranged to obtain an even distribution of moisture upon the plate cylinder with provisions for facilitating adjustment of rate of flow.

In a lithographic press, unlike a letter press which employs raised type, the printing plate is in the form of a fiat sheet in which the printing areas are treated to pick up ink from an ink form roller, whereas the non-printing areas are coated with a film of water and are non-receptive to ink. By the term water, used throughout, is meant a mixture of water and well known additives used in the art or any equivalent ink-repelling liquid. Water is applied to specific areas of a plate surface in varying amounts by a form roller made of resilient material and the present invention has to do with feeding water in the form of a thin film to the water form roller. Much time and effort has been expended in the past to regulate the feeding of water in order to supply the moisture at a desired rate. In an effort to secure an accurate and dependable system, the tendency has been to resort to relatively elaborate and expensive water feed mechanisms, which in spite of their complexity have not been satisfactory.

It is an object of the present invention to provide a water feeding or dampening system for a lithographic printing press which is capable of applying a film of water at a desired rate of feed which is consistant in operation and controllable from point to point along the length of the feed elements, with a high degree of precision. More specifically it is an object to provide an arrangement employing a cylindrical brush and in which the feed rate of the water at each point along the length of the brush may be finely adjusted to correspond to the printed form and, once set, remains constant.

It is a related object to provide a water feeding system employing a cylindrical brush utilizing the flicking action of the bristles in which the brush itself is of simple, inexpensive construction and in which the bristles are not subject to wear or change in their operating characteristics upon passage of time to any noticeable degree.

It is yet another object to provide means for controlling the rate of water feed over closely spaced regions along the length of the brush but which permits throw-off of the entire controlling mechanism to terminate the flow when necessary without disturbing the regional adjustments.

It is another object of the present invention to provide a Water feeding system for a lithographic press which utilizes the flicking action of the bristles on a cylindrical fountain brush but which is distinguished by novel geometry involving extremely close spacing between the brush and the drum which received the moisture and in which opportunity for scatter of water particles is minimized, enabling the usual shields and enclosures to be eliminated. In this connection it is a more detailed object to provide a brush type water feeding system having an extremely narrow escape angle and in which substantially all of the water particles not actually reaching the adjacent drum are recovered by an apron or extension formed along the 3,411,441 Patented Nov. 19, 1968 "ice edge of the water fountain, with automatic drainage into the body of water in the fountain. It is a general object to provide a brush type fountain roller in which the water droplets are required to move through only a short gap prior to striking the surface of the receiving drum but in which there is, nevertheless, a controllable distribution of the water along the length of the drum.

It is still another object to provide a water feeding system for a lithographic printing press which is of elegant simplicity employing a minimum number of rotating and structural elements and which may be constructed at much lower cost than competing systems while nevertheless characterized by a certain combination of features and geometry resulting in an order of efliciency, operating capability, and ease of operation and adjustment greatly exceeding that of similar brush type systems which have been used heretofore.

Other objects and advantages of the invention will become apparent upon reading the attached detailed description and upon reference to the drawings in which:

FIGURE 1 is an elevational view, foreshortened and with portions in section, of a water feeding systems constructed in accordance with the invention;

FIGURE 2 is a top view of one end of the system of FIG. 1;

FIGURE 3 is a somewhat diagrammatic cross section showing the preferred geometry of a dampening system;

FIGURE 3a is an enlarged fragment of FIG. 3;

FIGURE 4 is a transverse section taken through a deflector blade assembly, looking along the line 33 in FIG. 1;

FIGURE 5 is a fragmentary section taken along the line 55 in FIG. 4;

FIGURE 6 shows the motion limiting means for the blade mounting and adjusting shaft looking along the line 7-7 in FIG. 2;

FIGURE 7 is an elevational view of a modified form of the invention.

While the invention has been described in connection with a preferred embodiment, it will be understood that we do not intend to be limited to the particular embodiment shown but intend, on the contrary, to cover the various alternative and equivalent arrangements included within the spirit and scope of the appended claims.

Turning to the drawings and particularly to FIGS. 1-3, there is shown a system 10 for feeding a film of water to a printing plate 11 mounted on a plate cylinder 12. The system includes a fountain brush 15 having radially extending bristles 16 and having .an integral shaft 17 journaled in brackets 18, bolted or otherwise secured to side frames 19. The fountain roller is separately rotated by a drive motor 20 which may be outboard-mounted as shown having integral step down gearing, via a coupling 21.

Arranged below the fountain brush is a pan 25 of generally rectangular shape containing a body of Water 26 into which the tips of the bristles project, a water inlet 27 and an overflow connection 28. Water is constantly fed through the inlet 27 and the height of the drain connection determines the level which is to be maintained. For convenient removal for inspection or cleaning, the pan is provided at its ends with hangers 29 engaging suitable ledges formed in the brackets 18, the pan being locked in horizontal position by suitable means.

For engaging the tips of the bristles of the fountain brush 15, a deflector blade assembly 30 is provided. It will sufiice for the present to say that particles of moisture are propelled by flicking action from the bristles of the brush 15 onto the hydrophilic surface of a drum 31 mounted on a hub or shaft 32. To equalize distribution of the moisture, the drum 31 may be vibrated endwise as indicated by the arrow 33 in FIG. 2. The specific means for imparting the vibrating movement and the specific bearings for supporting the shaft 32 of the drum do not form a part of the present invention and hence reference may be made to the prior art for further details. The surface of the drum 31 consists of chrome plating upon steel so that the surface is hydrophilic, i.e., water accepting.

In rolling engagement with the drum 31. is a resilient water form roller 35 having a shaft 36 and mounted for rotating in suitable bearings, the details of which have not been shown. The water form roller 35 rolls in contact With the printing plate 11 on the cylinder 12 and with the drum 31, the drum being preferably overdriven with respect to the roller by a small percentage to provide a slight wiping action. The latter may be accomplished by gearing the drum to the plate cylinder and by using a drum of a diameter slightly larger than the diameter determined by the gear ration. The form roller has a resilient covering of synthetic material of desired hardness and elasticity. It may also be covered by commercially available liquid receptive sleeves or wraps. It will be understood that, during a press run, some of the ink from the plate may offset upon the form roller and the drum 31. In this event, such ink will not be further transferred to the brush or the water supply in pan because of the gap which exists between the brush and the drum.

In carrying out the present invention the deflector assembly is made up of a plurality of deflector blades arranged closely side by side along the length of the brush for bending and releasing bristles thus causing flicking of the water droplets from the tips of the bristles, which are arranged in a helical row. Each blade is separately rockable through a small angle for adjusting the penetration into the brush while permitting retraction or throw-off of the entire blade assembly without disturbing the existing individual blade adjustment, Thus, turning to the drawings, the deflector blade assembly 30 is seen to consist of a plurality of individual blade sections 41 which extend into the nip region between the brush and drum. The blade sections are mounted on a common shaft 42 which is rockable in bearing brackets 43, 44 which are fixed to the respective supporting or side frames 19. Since the blade sections 41 are identical, it will suflice to describe a typical unit shown in FIGS. 4 and 5. Here it will be noted that an individual blade, indicated at 45, is secured to a yoke 46 by means of machine screws 47 or the like. The yoke 46 includes spaced sidewalls 48, 49 which are apertured for reception of the shaft 42 and which contain between them a reference member 50 having arms 51, 52 and which is secured rigidly to the shaft by a set screw 53. Screwed into the arm 51 is a threaded adjusting key 55 which bears against the root 56 of the yoke. Interposed between the opposite arm 52 and the root of the yoke is a biasing spring 57 which serves to keep the tip of the adjusting key 55 bottomed on the yoke at all times. Thus with the shaft 42 in an operating position, turning the key 55 clockwise serves to swing the blade element clockwise as shown in FIG. 4 into deeper penetration of the bristles on the brush. Turning the key 55 in the opposite direction, accompanied by expansion or take-up of the spring 57, serves to reduce the degree of penetration. Adjusting the key in each of the mounts 41 thus serves to adjust the degree of penetration, and hence the intensity of the flicking action at adjacent regions along the length of the brush.

The bristles are formed of resilient fibers sufliciently stiff so that each bristle upon being bent and released, momentarily acquires a high angular velocity producing flicking or ejection of the water particles substantially radially as shown in FIG. 3a.

The amount of water transferred to the drum depends upon the fact that only a portion of the water on the brush at any given point is discharged in the form of droplets. When the blade element is adjusted for deeper penetration into the brush, the bristles, in that region, are held back all) for a slightly longer time than when penetration is lighter, so that the bristles have more stored energy resulting in more rapid velocity of the bristle about its base or point of connection when released. This has the effect of ejecting water which is more deeply located within the brush structure so that the degree of blade penetration determines the rate of water feed. In short, turning a key in one direction or the other constitutes a convenient means for varying the quantity of water applied to each incremental length of the drum, and hence the plate, thus securing control of feed which has been diflicult to obtain heretofore. One advantage of this mode of adjustment is that a relatively non-critical and hence non-expensive brush may be employed. In a practical case using a brush roller having a nominal diameter of approximately six inches, the bristles may be formed of crimped nylon fibers having a diameter on the order of 0.008 inch and a free length of about Vs inch. The height dimension need not be critically constant over the length of the brush, and individual bristles may vary in free length over a range of approximately inch. In accordance with one of the features of the invention a generally round brush is employed consisting of a row of bristles wound about the body of a roller, Where bristles are used covering less than the total area, less water is picked up during each revolution, and the adjustment of the blade assembly is thus less critical than where the brush is completely covered with bristles. In other words, the range of penetration at the tip of the blades may be made relatively great with only a moderate change in the rate of feed. In any event the rate of feed may be finely controlled with relatively gross movement of the key and blade element. This does not mean that the blade must penetrate very deeply into the brush, and an adequate feed rate is established using a penetration of approximately twenty percent, i.e., a penetration of about A; inch for a inch bristle, and with the useful adjustment, say, inch on either side of this. It is to be noted that adequate feed has been brought about with direct dipping of the bristles int he water of the fountain without necessity for resorting to any auxiliary water removing or flicking means between the region of dipping and the blade edge where the feed, or flicking, occurs. Indeed, it is one of the features of the present arrangement that the dipping of the bristles is relatively non-critical and the bristles may be dipped to a depth of /8 inch, i.e., to a suflicient depth so that leveling of the brush is non-critical and so that a simple overflow constitutes a sufficiently accurate means to maintain the water level in the pan. In set-ups of the type disclosed successful wetting of the bristles can be achieved with a clip on the order of f and which may be as shallow as inch or as great as, say, inch, although it will seldom be necessary to increase the amount of the dip beyond this.

It is one of the more detailed features of the present invention that the pitch of the helix is related to the width of the blade elements being used. While the number of blade elements, and key positions, will be determined by the fineness of control desired, it is preferred that the helical pitch of the brush be substantially less than the width of the narrowest blade in the blade assembly. This insures that each blade element is engaged at all times by at least one row of bristles and hence is, at all times, actively controlling water fed to the corresponding portion of the hydrophilic drum. We prefer to employ a set of blade elements arranged substantially edge to edge, and having a width say, up to five inches. On the other hand, where the requirements are less exacting, the Width of the blade may be made several times as great, without departing from the invention. The stroke of drum vibration, if used, need not be any greater than employed in conventional water feeding arrangements.

In order to economically manufacture a fountain brush of the type described above, and to facilitate replacement of the brush element, the bristles are mounted in a metal strip 61 which is U-shaped in cross section which may be furnished in a straight length and simply wound in place on the body 15.

It is one of the further features of the construction that the blade assembly 30 is so mounted that the blade elements are substantially tangential to the brush or are tipped or elevated with respect to a true tangent by an angle a which preferably lies within the range of 0-15, (FIG. 3). The edges of the blade element are preferably tapered but present a squared rather than a knife edge. Using a shallow blade angle and the degree of blade penetrapipp discussed above, the bristles are deformed gradually and the flicking action is free of any abrading effect so that wear, at the preferred operating speed of 15- 45 r.p.m., is of little consequence. Any wear that does occur can be readily compensated for by individual blade adjustment.

It is one of the important features of the present invention that the hydrophilic drum is placed in the path of movement of the droplets at a much closer spacing than has been conventionally employed in brush-type water feed systems in the past, with the tip of the blades of the deflector assembly being a short distance from a plane defined by the axes of the brush cylinder and the hydrophilic drum, respectively, so as to produce an extremely small escape angle for any droplets which may not fall upon the surface of the drum. In discussing the escape angle reference may be made to FIG. 3, the primary escape angle in this figure being defined by a first line 71 drawn from the tip of the blade tangent to the surface of the drum 31 and a second line 72 which just clears the tips of the bristles as they straighten out after being bent by the blades. The line 72 is preferably constructed by drawing a tangent to the brush profile at the center line 73 defining the closest approach of the brush to the drum. Employing a brush-to-drum spacing s of inch and with a blade tip offset, indicated at b, on the order of inch, the primary escape angle e is reduced to the small value of 20 degrees. However it is not necessary to maintain the angle at this small value and it is contemplated that such angle may, upon slight changes in geometry, be as large as 30 without departing from the present invention. Thus the blade offset b may be reduced to as little as about inch and the spacing between the brush and the drum may be increased to approximately /a inch. At the other extreme, the offset may be increased to about an inch and the spacing decreased to as little as about A inch. These two variables are to some extent related since with extremely small spacing between the brush and the drum, the blade offset must be sufficient to accommodate the edges of the blades and to permit silencing by rocking of the blade control shaft 44 in a direction to disengage the blade elements from the tips of the bristles.

In carrying out the invention an extension is provided on the pan for intercepting and draining the escaped particles back in the pan. In the present instance, the extension, indicated at 75, is integral with the pan 25 and extends the full length of the pan, i.e., beyond the ends of the brush cylinder, to collect water particles. In the form shown in FIG. 3 the extension includes an upraised ledge or rim 76 which extends, as shown, to within a short distance of the surface of the drum to provide a substantially enclosed triangular space 77. While the extension 75 is above water level in the illustrated embodiment, it may, if desired, be an extension of pan 25 without affecting its collecting function. Thus the present construction is to be distinguished from prior brush-type moisteners requiring shields and enclosures to contain the splatter from the brush. Lack of shields and enclosures not only makes the present arrangement more compact but it results in a substantial reduction in the cost and in greater accessibility to the component parts for inspection, service or adjustment.

In order to rock the blade adjusting and mounting shaft between the limits defining working and throw-off positions, the shaft is equipped with a throw-off arm 80 which is clamped to the shaft by a suitable screw 81 and which has adjustable stops to define the limits of movement. The Working position is established by a first adjustable stop 82 and the throw-off position by a second adjustable stop 83, the stops being respectively above and below the arm 80. Such stops are conveniently mounted in spaced projections 84, 85 integrally formed as part of the right hand bearing block 44 (see FIG. 2.) A clamping member 86 in the form of a wing nut serves to lock the throw-off arm 80 in either of its two positions. When it is desired to change the feed rate for the system as a whole, this can be easily accomplished by a slight change in the adjustment of the stop 82 without necessity for changing the adjustments of the individual blades. It is to be particularly noted that the stop 82 serves to define the working position of all of the blade elements and that the blade elements retain their original adjustments relative to one another completely unaffected by bodily movement of the shaft.

It will be apparent to one skilled in the art, in view of the foregoing that while the dampening system described and claimed herein is of elegant simplicity, it has all of the structural and operating features desired by a press operator combined with economy and capable of operating over long periods of time without care or maintenance.

While the invention has been described in connection with one embodiment, the invention is not limited to such embodiment and includes arrangements in which the cylinders are arranged vertically, rather than horizontally, to conserve space and for integration with pre-existing press designs in which available space in the horizontal direction is not available.

Thus, referring to the dampening arrangement in FIG. 7, a fountain brush 15a is provided mounted in bearing brackets 18a and driven at a slow rate of speed by a drive diagrammatically illustrated at 20a. The bristles 16a of the brush dip to predetermined depth in a water pan a having suitable means, as in the preceding embodiment, for maintaining a constant water level. Mounted above the fountain brush and spaced slightly from it is a hydrophilic drum 3101, similar to that previously described, inrolling engagement with a resiliently surfaced form roller a which engages the plate 11a on plate cylinder 12a. The form roller and drum are both driven by suitable means, not shown, at the substantially same peripheral speed as the plate.

For bending the bristles of the brush, a blade assembly 3011 is provided having a transversely extending shaft 42a suitably mounted in the press side frames and which serves to support a plurality of blade elements 45a secured to yokes 46a. The yokes are constructed as shown in FIG. 5, each having a reference member 50a with an associated adjusting screw a and take up springs 57a. However, in the present embodiment each blade 45a is secured to the lower end face of the yoke by means of suitable screws 47a, with the result that the blades 45a extend generally horizontally rather than generally vertically. The blades 45a are of such length that the tips fall just short of the region of closest approach of the brush and the drum. With the blades adjusted .as earlier described, the water droplets are flicked upwardly against the surface of the drum 31a. Any droplets which miss the drum tend to fall back onto the brush or into the pan by an action of gravity, so that there is no need, in the present embodiment, to provide means for subtending the droplet escape angle. It will be understood in FIG. 7 that the figure is intended primarily to show the location of the rollers and drums. The use of closely spaced blades in multiple and other details of construction not visible in this figure will be apparent from the earlier views.

The term shaft in the following claims refers to the axially-extending member upon which the individual blades are mounted and with respect to which they are adjusted.

We claim as our invention:

1. In a dampening system for a lithographic press having a plate cylinder and a printing plate, the combination comprising a fountain brush of cylindrical shape having bristles extending continuously about the periphery thereof and having means for imparting continuous rotation, a Water fountain including a pan assembly under the brush having means for maintaining the Water at a constant depth so that the bristles pick up water as they rotate, a drum having a hydrophilic surface adjacent the brush, a deflector blade assembly having a plurality of deflector blades arranged closely side by side generally tangentially along the length of the brush with the alined edges of the blades being positioned at the nip of the brush and drum but offset from a plane defined by the brush and drum so that the engaged bristles are progressively bent for flicking of water droplets from the tips thereof, the bristles being formed of resilient fibers sufliciently stiff so that each bristle momentarily acquires a high angular velocity as it straightens out causing ejection of Water particles therefrom in a substantially radial direction, said drum being arranged sufiiciently closely adjacent the brush cylinder as to be in the path of substantially all of the ejected droplets, a water form roller of resilient material in rolling contact with the drum and the printing plate for placing .a film of (water on the plate, said form roller and hydrophilic drum being rotated at substantially the speed of the plate, said blade assembly including a mounting shaft and each of said blades having means for individual rocking movement about said shaft for individual adjustment of penetration into the corresponding section of the brush,

and means for moving the mounting shaft laterally between a working position in which the blades engage the brush and a retracted position in which the blades are free of the brush for silencing the feeding of water while maintaining the relative positions of the blades with respect to the mounting shaft.

2. The combination as claimed in claim 1 in which the hydrophilic drum is closely spaced to the brush Within a range of about inch to about /3 inch and in which the edges of the blades are offset from a plane defined by the axes of the brush cylinder and drum within the range of about inch to about 34 inch thereby to provide a limited available escape angle for any droplets which may pass free of the drum.

References Cited UNITED STATES PATENTS 176,193 4/1876 Rhell 101-148 1,801,830 4/1931 Winstanley et al 101-l48 2,118,517 5/1938 Mitchell 101148 2,727,267 12/1955 Osgood 15182 2,853,004 9/1958 Sanker 101-l48 2,954,933 10/1960 Clare 239220 2,986,337 5/1961 Clare 239-220 3,257,940 6/1966 Strudwick 101-148 FOREIGN PATENTS 737,988 10/ 1955 Great Britain.

ROBERT E. PULFREY, Primary Examiner.

EUGENE H. EICKHOLT, Assistant Examiner.

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