COMPENSATION DEVICE FOR CONTROLLING THE CLOTH IN APPARATUS FOR CLEANING THE CYLINDERS OF PRINTING MACHINES

Abstract: The portion of cloth (T) located between the feed reel (R1) and take-up reel (R2) runs around the presser (P) which on command pushes a portion of the cloth against the cylinder to be cleaned (D), and also around a dancer (1) which takes up cloth when the said presser moves from the active position to the rest position and which conversely releases cloth when the presser moves from the rest position to the active position. The dancer consists, for example, of a strip which has a rounded edge (101) touching the cloth, and which is opposed and parallel to the presser and is fixed structurally to the latter by suitable means (4, 5), in such a way that it moves with the said presser in a synchronized and opposite way with respect to the supporting bar (B).

Description: TITLE: "COMPENSATION DEVICE FOR CONTROLLING THE CLOTH IN APPARATUS FOR CLEANING THE CYLINDERS OF PRINTING MACHINES" DESCRIPTION The invention relates to apparatus for cleaning the cylinders of printing machines, comprising a bar parallel to the cylinder to be cleaned and located at a short distance from it, the bar normally being fixed, and having in a longitudinal position, on the side facing the cylinder, a rectilinear recess in which is guided a presser having an elasticaily yielding membrane on its outer side. The bar houses actuators, usually pneumatic, which on command push the presser against the cylinder to be cleaned, to bring into contact with the cylinder a piece of fabric or cloth onto which cleaning fluids have previously been sprayed by a row of nozzles or holes located on the side of the bar facing the cloth. The ends of the bar are fixed to a pair of shoulders which also rotatably support the ends of a pair of reels for feeding and taking up the said cleaning cloth respectively. The shaft of the feed roll is provided with a suitable friction device and can be locked on command, while the shaft of the take-up reel is connected to suitable means which on command make it rotate to transfer a portion of clean cloth above the presser into a lowered position, while this portion of cloth passes over a row of needles which spray it with liquid and while a corresponding portion of dirty cloth is wound onto the take-up reel. When the presser approaches the cylinder to be cleaned, the cloth take-up reel is locked. The cloth feed reel is also locked, to prevent more cloth from being drawn from this reel by the contact of the cloth with the cylinder to be cleaned, which is rotating. Consequently, the cloth is stretched cyclically by the presser and the portion of cloth which lies between the two reels and is acted on by the presser increases in length progressively, with the disadvantage that it can interfere with the impression cylinder or with clamps associated with it, and with the disadvantage of having less contact with the side of the bar on which the cleaning-fluid supply nozzles or holes open, with consequent dripping of this liquid. Certain types of printing cylinder are provided with paper-gripping clamps which project from the lateral surface of the cylinder, and in order to avoid these clamps the aforesaid cleaning device has to be positioned at an appropriate distance from the cylinder. This creates further problems at the time of activation of the presser of the cleaning device, since the presser has to travel for a considerable distance before bringing the cloth into contact with the cylinder to be cleaned, the opposite ends of this cloth being held by the locked shafts of the feed and take-up reels. The invention is designed to overcome these problems with the following idea for a solution. A dancer device, having the function of compensating for the drawing and release of cloth carried out by the movement of the presser, of keeping the cloth correctly tensioned at all times, and of avoiding the aforesaid disadvantages, is positioned between the bar with the presser and the cloth take-up reel. Further characteristics of the invention, and the advantages derived therefrom, will be made clearer by the following description of a preferred embodiment of the invention, illustrated purely by way of example and without restriction in the figures on the attached sheets of drawing, in which: - Figs 1 and 2 show a cross section of an improved cleaning apparatus according to the invention, showing the presser at rest and active respectively; - Fig. 3 shows an improved cleaning apparatus according to a variant design. In Figure 1 , D indicates the cylinder of the printing machine, provided with the projecting paper clamp Z mentioned in the introduction to the present description. The bar B of the cleaning device is placed parallel to the cylinder D, and is fixed at its ends to a pair of shoulders S which support, parallel to the bar, the reels R1 and R2, for feeding and taking up, respectively, the cloth T running over the said bar. The shaft of the reel R1 is controlled by friction means and can be locked on command by known means, while the shaft of the reel R2 is connected to known means of unidirectional and irreversible rotation, for example in the anticlockwise direction. In running over the bar B, the cloth T passes over a rectilinear recess C in which is mounted the presser P, which has its active part PA made from a suitable elasticaily yielding material and which is connected to means (not illustrated) which normally keep the presser withdrawn into the corresponding recess, but which on command can make it project to bring it into contact with the active part PA and with the cylinder D to be cleaned, with the interposition of the cloth T (see Fig. 2). Before the recess C, the bar B is provided with a row of holes or nozzles indicated schematically by U, which on command feed to the cloth a cleaning fluid consisting of a mixture of water and solvent carried by pressurized air. According to the invention, the portion of cloth T located between the reels R1 , R2 also runs over the rounded edge 101 of a dancer strip 1 parallel to the presser P and housed in a recess 2 of the bar B, this recess having in its base a plurality of holes 3 suitably spaced apart, engaged slidably by hollow spacers 4, through which pass screws 5 by means of which the dancer strip 1 is fixed to the body of the presser and made to move integrally with it. The operation of the apparatus designed in this way is simple and evident. When a clean portion of cloth T is passed over the presser P, the latter is in the withdrawn position of Figure 1 , the shaft of the reel R1 is friction-controlled and the reel R2 rotates in the anticlockwise direction, while the dancer 1 is in the extended position, so that the portion of cloth located between the reel R2 and the bar B is made to follow a broken path whose length is greater than that which would be found in the absence of the dancer 1. At this stage the nozzles or holes U spray the cleaning liquid onto the cloth which is passing. When the cloth has been brought into position, the shaft of the reel R1 is locked, and while the presser P is activated to bring the cloth into contact with the cylinder D to be cleaned, the dancer 1 withdraws into its housing 2, as shown in Figure 2. The apparatus is designed in such a way that the decrease in length of the portion of cloth located between the dancer 1 and the reel R2, following the withdrawal of the dancer, is essentially equal to the increase in length of the portion of cloth located between the reel R1 and the dancer 1 following the extension of the presser P. Conversely, when the stage of cleaning the cylinder D has terminated, the decrease in length of the portion of cloth located between the reel R1 and the dancer 1 , following the withdrawal of the presser P as shown in Figure 1 , is essentially equal to the increase in the length of the portion of cloth located between the dancer 1 and the reel R2 following the extension of the dancer 1. Clearly, with the described solution, the cloth is never subjected to longitudinal stretching during its passage over the presser P, and the portion of cloth located between the feed and take-up reels remains correctly tensioned at all times, so that whenever the take-up reel draws in a portion of soiled cloth, a corresponding portion of clean cloth is unwound from the feed roll and positioned over the presser, and the same portion of cloth remains correctly tensioned longitudinally at all times and in constant contact with the side of the bar on which the cleaning-fluid supply holes or nozzles U open, thus avoiding all the disadvantages of the known art. Figure 3 shows a variant in which, while the direction of rotation of the impression cylinder D remains unchanged, the positions of the reels R1 and R2 and of the cleaning-fluid supply holes or nozzles U relative to the bar with the presser P are interchanged with respect to the solution shown in Figures 1 and 2, with the advantage that no means of locking the shaft of the feed reel R1 are required, and the only requirement is for a unidirectional and irreversible rotation of the take-up reel R2. In this case, it is not necessary to modify the position of the dancer 1 , which remains the same as in the solution of Figures 1 and 2. During the extension travel of the presser P, the cloth is not drawn from the friction-controlled feed reel R1 , since the dancer 1 progressively releases cloth to the presser, so that the cloth is not subjected to longitudinal tension. When the cloth comes into contact with the roll D to be cleaned, the direction of rotation of the latter is such that the cloth is drawn from the reel R2, which is unable to rotate, since it is connected, as stated above, to unidirectional and irreversible means of rotation. It is to be understood that the description omits the details of construction of the means controlling the shafts of the reels R1 and R2, since these are known. It is also to be understood that the description refers to a preferred embodiment of the invention, to which numerous variations and modifications can be made, especially in respect of construction, for example in relation to the fact that the strip 1 can be replaced by another return means, possibly of the rolling type, and/or the fact that the dancer can be driven by the presser not in a direct way as illustrated, but by means of an indirect solution. Thus, the dancer could be of the oscillating type and could act on the cloth through elastic means, by fluid pressure or by the effect of gravity.

Claims: CLAIMS 1. Compensation device for controlling the cloth in apparatus for cleaning the cylinders of printing machines, of the type comprising, for example, a bar (B) parallel 5 and close to the cylinder (D) to be cleaned, supported at its ends by shoulders which rotatably carry the ends of two reels (R1 , R2) parallel to the said bar and designed respectively to feed and take up a cloth (T) which runs on the side of the said bar on which opens a row of holes or nozzles (U) which on command uniformly spray cleaning fluid onto the cloth before the cloth passes over the active part (PA) of a 0 presser (P) which is housed in a longitudinal recess (C) of the said bar and which can be extended by suitable means to bring the wetted portion of cloth into contact with the cylinder to be cleaned, characterized in that the portion of cloth located between the said reels (R1 , R2) also runs over a dancer (1 ) which is positioned parallel to the said presser (P) and which is designed to take up cloth when the 5 presser moves from the active position to the rest position and which conversely releases cloth when the presser moves from the rest position to the active position, the whole being designed in such a way that, following the movement of the presser, the portion of cloth lying between the said reels (R1 , R2) is never subjected to undesired longitudinal stretching and remains at all times correctly tensioned and in 0 contact with the said bar or with the presser, until the feed reel is empty. 2) Device according to Claim 1 , characterized in that the dancer (1 ) comprises a strip parallel and essentially opposed to the presser, a rounded edge (101 ) of this strip being in contact with the cloth and the strip being made integral with the body of the presser (P) by means of screws (5) and spacers (4) passing through the holes 5 (3) formed in the bar (B), the whole being designed in such a way that the said strip is made to approach the bar and release cloth when the presser moves away from the bar and carries out its active travel, thus stretching the cloth released by the strip, and vice versa, in such a way that, when the presser returns to the rest position and releases cloth, the cloth is taken up and stretched by the strip which moves away o from the bar. 3) Compensation device according to Claim 2, characterized in that the soiled cloth take-up reel (R2) is positioned next to the dancer (1) and has its shaft connected to unidirectional and irreversible means of rotation, while the clean cloth feed reel (R1 ) is positioned next to the presser (P) and has its shaft connected to means which on command alternate between the functions of friction control and locking, the direction of rotation of the roll to be cleaned (D) being such that it draws the cloth from the said feed reel (R1 ). 4) Device according to Claim 2, characterized in that the clean cloth feed reel (R1 ) is positioned next to the dancer (1 ) and has its shaft connected to friction means, while the soiled cloth take-up reel (R2) is positioned next to the presser (P) and has its shaft connected to unidirectional and irreversible means of rotation, the direction of rotation of the roll to be cleaned (D) being such that it draws the cloth from the said take-up reel (R2).

Inventors: CORTI MARCO, FUMAGALLI RICCARDO, CORTI, MARCO, FUMAGALLI, RICCARDO
Applicants: CORTI MARCO, FUMAGALLI RICCARDO, CORTI, MARCO, FUMAGALLI, RICCARDO
Application year: 2000
Main classification: B41F35
IPC codes: B41F35