FR2718996A1 - A method of washing the casing of a cylinder of a rotary printing machine. - Google Patents

Abstract

A method of washing the casing of a cylinder, in which a cleaning cloth, onto which detergent has been sprayed, can be pressed against, for example, a blanket as the cylinder rotates, the cloth undergoing heavy feeds. 'a step on a small section when the previous section is dirty. The cleaning process (6) is carried out during one revolution of the cylinder by resting a clean section of the fabric at the start (1) of the blanket, then the fabric is removed (at 7) in the area of the last third, it then undergoes an advance of another step, then a clean section of it is brought back to bear against the blanket, this process preferably being repeated twice. Application in particular to rotary offset printing machines.

Description

The invention relates to a method of washing the envelope of a

  cylinder, preferably a blanket cylinder of offset-printing rotary machines, in which a cleaning cloth, on which a detergent has been sprayed, can be placed against the blanket while the blanket cylinder is rotating, the cleaning being advanced one step on a small stretch when the

previous stretch is fouled.

  In known roll washing devices of a sheet-printing machine (DE 42 09 642 A1), a small section of a cleaning cloth is placed by means of a pressing element, for example against the blanket. a corresponding cylinder, the pressure being exerted by compressed air which is directed on the pressing element and which pushes the latter outwards. A cleaning liquid sprayed on the fabric or on the cylinder dissolves the remains of ink adhering to the latter. During the rotational movement of the cylinder to be cleaned, the cleaning cloth absorbs the washing liquid and the dissolved ink residues and thus removes them.

  to an extent that corresponds to its absorption capacity.

  When the blanket is badly fouled, the cleaning agent can be expelled with the ink residues on the blanket in front of the blanket after the cleaning capacity of the cleaning cloth has been exhausted. cloth and that it is directed into the cylinder channel at the end of the blanket. The printer is then obliged to remove the dirty detergent by hand to extract it from the cylinder channel. This implies, however, that the machine must be stopped for washing and that the print must perform manual cleaning work from one printing unit to the next. The object of the present invention is therefore to create a process by means of which the cleaning process can be carried out automatically and which avoids the printer

  to have to perform a posteriori manual work.

  A solution to the subject of the invention is characterized by the following steps of the method: a first cleaning process performed during a revolution of the blanket cylinder consists of placing a clean section of the cleaning cloth at the beginning of the blanket and briefly move the fabric away from the latter, preferably in the area of its last third, the cleaning cloth undergoes a step advance, a clean section of the fabric is pressed against the blanket, the fabric the cleaning process is preferably repeated twice, the last cleaning process is carried out by pressing a clean section of the fabric against the beginning of the blanket and this fabric is removed at the end of the blanket. The brief removal of the blanket cloth while the machine is turning allows, by advancing this fabric a step, to put a clean section against the turning blanket and to make him absorb a supplement of detergent and residues d ink near the end of the blanket. The heavily fouled portion of the cleaning cloth is wound by the cleaning device and thus a major part of the dirty cleaning liquid is removed. The washing process is repeated during the next revolution of the cylinder during which only a small portion of the blanket which has rotated under the cleaning cloth during the removal of the washing device is not washed. The amount of wash liquid and fouling residues by the ink therein is relatively small, so that most of the blanket has already been cleanly washed when the last cleaning process takes place. The clean section of the fabric that is then used is able without difficulty to remove this fouled band blanket and perform the complete cleaning. This requires only a few revolutions of the cylinder and the washing process can be performed while the machine is running at high speed. According to an advantageous embodiment of the method, the cleaning cloth is removed for example each time in the area of the last third of the blanket and its resting against the latter takes place with a slight time lag between the individual cleaning processes. It is thus possible to ensure that the remaining band of the blanket on which dirty cleaning liquid remains very narrow and thus to further reduce the amount of this dirty liquid. A variant of the process is characterized by the following steps: a first cleaning process is carried out during a revolution of the blanket cylinder with the support of a clean section of the fabric against the beginning of the blanket, the cleaning cloth is away from the blanket in the area of the last third of the latter, the cleaning cloth undergoes a step advance, the direction of rotation of the cylinder undergoes a reversal beyond the end of the blanket, the cleaning process is to preferably repeated three times, each time with reversal of the direction of rotation of the cylinder, the last cleaning process is performed in the direction of rotation opposite to that of the machine by pressing a clean section of the cleaning cloth against the end of the blanket, then away from this fabric at the beginning of the blanket, the direction of rotation of the blanket cylinder is inverted to be put in the normal direction of operation

of the machine.

  This solution also prevents washing liquid and ink residues being forced back into the cylinder channel and must be removed by hand when the blanket is heavily fouled. In this case, it is also possible to execute an automatic cleaning program in which the machine rotates the cylinder one revolution forward and backward, thus cleaning all blanket cylinders of a printing machine in several colors. The cleaning process can be carried out automatically without the intervention of the printer. The roughly five revolutions of the cylinder that are needed for the cleaning process can be performed in a

very short time.

  According to an advantageous feature of the process, the removal of the cleaning cloth is carried out each time in the area of the last third of the blanket with a slight shift in time. This has the advantage that the strip remaining at the end of the blanket each time when the cleaning cloth is moved away can remain very narrow, so that the last washing process which is carried out in the opposite direction of rotation of that of the

  running the machine completely cleans the blanket.

  An exemplary embodiment of the two solutions according to the invention is diagrammatically represented in the drawings in which: FIG. 1 is a diagram of the first solution, FIG. 2 is a diagram of a variant of the first solution, and

  Figure 3 is a diagram of the second solution.

  Figures 1 to 3 show the blanket of the corresponding cylinder and the channel of the latter developed, the channel 3 forming an intermediate space between the beginning 1 and the end 2 of the blanket in the direction of rotation of the corresponding cylinder. The ink layer 4 corresponds each time to its quantity which is on the blanket. The direction of rotation 5 is to the right in FIGS.

  2 and corresponds to a rotation in the clockwise direction.

  The first cleaning process begins during a revolution of the blanket cylinder by pressing a clean section of the cleaning cloth against the beginning of the blanket, the dissolved ink residues being removed along the curve 6 (FIG. 1). The fabric 6 is briefly moved away from the blanket by one step to allow a clean section to be placed in the area of the wiping surface. The fabric is immediately returned to the blanket. After pressing again 8, the last part of the blanket is cleaned according to curve 9. The broken line 10 which is drawn in line with curve 6 indicates the manner in which the fouling of the cleaning cloth reaches a maximum with the washing processes used so far, so that in the end, no more dirty cleaning liquid is absorbed. The cleaning cloth undergoes a new advance one step beyond the end 2 of the blanket and

  so a clean stretch is available at the beginning 1.

  The curves 11 and 12 illustrate the two following cleaning processes in which a distance also takes place at 7 and the restoring of the cleaning cloth is carried out at 8. The curves 13 and 14 represent the manner in which the cleaning is carried out. carried out after resupply of the cleaning cloth. The last cleaning process corresponds to the curve 15 and in this case the fabric remains in support from the beginning 1 until the end 2 of the blanket and the dirty detergent remaining in the

  band between slots 7 and 8 is absorbed.

  In addition, curve 15 rises to a maximum of 16. This is, however, significantly below the maximum absorption capacity of the cleaning cloth. Then,

  other sweeps of the cylinder still take place.

  FIG. 2 represents in principle the same cleaning process as that of FIG. 1, but the distance 7 is slightly offset in time during the individual cleaning processes 6, 11 and 12 and the restoring 8 is also shifted in time correspondingly. Thus, the uncleaned area during the first three cleaning processes 6, 11 and 12 shrinks. As a result, the maximum 16 of the last cleaning process is lower along the curve

15.

  In Figure 3, the cleaning is changed, because the first process takes place according to the curve 6 and the fabric is removed at 7 in the area of the last third of the blanket. In this embodiment, however, the fabric undergoes a step advance and is no longer placed against the blanket. According to this embodiment, the order

  the machine reverses the direction of rotation of the cylinder

  past the end 2 of the blanket and the second cleaning process is also carried out with a clean section of the fabric at the end 2 and it proceeds according to the curve 11 '. The fabric is also distant in 7 'from the beginning 1 of the

  blanket shortly before the end of the cleaning process 11 '.

  In this case also, the fabric then undergoes a step advance, then it is put back in support after reversing the direction of rotation of the blanket cylinder at the beginning 1 according to the curve 12 'r It is advantageous in this case to make the distance 7 with a small offset in time, as shown in Figure 3. Then again takes a step forward, then the next cleaning process according to the curve 17. In this case also, the distance 7 'takes place with time lag, so that another cleaning process can be performed according to the curve 18. After inversion of the direction of rotation of the cylinder and resupply of a clean section of the fabric, a last cleaning process is carried out in the opposite direction to the normal operation of the machine and leaves behind a clean blanket. Then there is only another reversal of the direction of rotation of the machine and therefore of the blanket cylinder which then turn in the

normal direction of walking.

  Other cylinders, for example the printing cylinder of an offset printing machine, can be washed in the manner described.

washed as described.

Claims (5)

  1. A method of washing the casing of a cylinder, preferably a blanket cylinder of offset-printing rotary machines, according to which a cleaning cloth, on which a detergent has been sprayed, can be placed against the blanket while the corresponding cylinder rotates, the cleaning cloth being stepped a step on a small section when the preceding section is fouled, characterized by the following steps: a first cleaning process (6) is performed during a revolution of the cylinder by pressing a clean section of the fabric against the beginning (1) of the blanket, the cleaning cloth is briefly removed (7) from the blanket, preferably in the area of the last third of the latter, l cleaning cloth is advanced by one step, a clean section of the fabric is pressed against the blanket (8), the cleaning cloth is advanced one step beyond the end ( 2) Blanket, the process the cleaning process is preferably repeated twice (11, 12), the last cleaning process (15) is carried out by pressing a clean section of the fabric against the beginning (1) of the blanket and this fabric is   away from the blanket at the end (2) of the latter.   2. Method according to claim 1, characterized in that the removal of the cleaning cloth (7) of the blanket, each time preferably in the area of the last third of the latter, and restoring support (8) take place with a slight lag in the time between individual cleaning processes.   3. A method of washing the casing of a cylinder, preferably a blanket cylinder of rotary offset printing machines, in which a cleaning cloth, on which a detergent has been sprayed, can be pressed against the blanket while the corresponding cylinder rotates, the cleaning cloth undergoing a step advance on a small section when the previous section is fouled, characterized by the following steps: - a first cleaning process (6) is performed during a revolution of the cylinder by pressing a clean section of the fabric against the beginning (1) of the blanket, - the cleaning cloth is removed (7) from the blanket, preferably in the area of the last third of this last, - the cleaning cloth undergoes a step advance, - the cylinder undergoes a reversal of the direction of rotation beyond the end (2) of the blanket, - the cleaning process is preferably repeated three times , in each a case with inversion of the direction of rotation of the cylinder, - the last cleaning process is carried out in the opposite direction to that of the running of the machine by pressing a clean section of the fabric against the end (2) blanket and the fabric is removed at the beginning (1) of the blanket, - the direction of rotation of the blanket cylinder is inverted to be put in the normal direction of the blanket machine running.   4. Method according to claim 3, characterized in that the cleaning cloth is removed in each case (7, 7 ') in the area of the last third of the blanket   with slight lag in time.   5. Method according to one or the other   1 and 3, characterized in that the fabric of   cleaning is placed offset against the beginning (1) / end (2) of the blanket during the first processes of cleaning (6, 11, 12).