GB2259053A

GB2259053A - Drive input point in a rotary printing machine.

Info

Publication number: GB2259053A
Application number: GB9214237A
Authority: GB
Inventors: Karlheinz Fischer; Victor Hefftler; Christian Ziegenbalg; Dietmar Mueller
Original assignee: KBA Planeta AG
Current assignee: KBA Planeta AG
Priority date: 1991-07-06
Filing date: 1992-07-03
Publication date: 1993-03-03
Anticipated expiration: 2012-07-03
Also published as: GB2259053B; GB9214237D0; DE4122443A1; FR2679488B3; FR2679488A1

Description

2 2 - 2 1 ")'.,; DRIVE INPUT POINT IN A ROTARY PRINTING MACHINE The

present invention relates to a rotary printing machine and has particular reference to the determination of the drive input point in such a machine.

Drive printing mechanisms, by way of which the entire driving power is fed into a rotary printing machine in unit mode of construction, have been known for a long time. The drive is of such a nature that gearwheels of adjacent sheet-guiding cylinders, for example impression cylinder and transfer drum, mesh with each other and form a closed.gear train in the printing machine.

Also known are single-motor drives, which have a V-belt driving a pinion which engages the gearwheel of a transfer drum or impression cylinder. The association of such a single-motor drive with a printing mechanism forms a drive printing mechanism. In a printing machine installation consisting of feeder printing mechanism, sequential printing mechanism(s) and delivery printing mechanism, any one of the sequential printing mechanisms can be the drive printing mechanism.

The position of the drive printing mechanism in the machine determines how much driving power must be transmitted from the gearwheel coupled with the pinion to the two adjacent gearwheels of the gear train.

If, for example, the middle unit in a machine with five printing mechanisms is the drive printing mechanism, then the driving power to be transmitted rearwardly in the direction of the sheet feeder and 1 2 forwardly in the direction of the sheet delivery is approximately equal.

In a machine with four printing mechanisms, or in machine with any other even number of printing mechanisms (6, 8 or 10), the driving 5 powers to be transmitted forwardly and rearwardly are different.

In the known drive printing mechanisms with single-motor drive, the pinion always engages at the same point or at a constant angle to the connecting line of the tooth engagement of the adjacent gearwheels independently of the location of the drive printing mechanism within the printing machine. It is disadvantageous in this constant arrangement of the pinion that, due to the different driving power to be transmitted forwardly and rearwardly in the gear train, the resultant of the force acting on the bearing location of the driven cylinder is different in magnitude and direction in dependence on the position of the drive printing mechanism in the machine. Unpredictable and undefined bearing forces can arise, which can cause double impression phenomena in the drive printing mechanism to the impairment of the printed image.

There is thus a need for a drive arrangement in a rotary printing machine in which measures may be able to be taken so that the resultant of the gearwheel forces related to the printing process may be able to be kept almost constant independently of the driving power to be transmitted forwardly and rearwardly in a gear train for printing mechanism drive.

3 - According to the present invention there is provided a rotary printing machine comprising a plurality of printing mechanisms arranged in succession, a closed gear train comprising a first gearwheel arranged to transmit drive to one of the mechanisms and a plurality of second gearwheels arranged to be d.riven from the first gearwheel and to transmit drive to the remaining mechanisms, and a pinion drivingly engaging the first gearwheel at a position selected to be dependent on the quotient of the number of mechanisms upstream of said one mechanism divided by the number of mechanisms downstream of said one mechanism.

A machine embodying the invention may have the advantage that the resultant of all gearwheel forces related to the printing process, including the influence through a blanket cylinder, may be able to be kept almost constant in direction and magnitude independently of the driving power which is to be tradmitted by the first gearwheel forwardly and rearwardly in the gear train. Since it is not fixed in production of the drive printing mechanism in which location the drive printing mechanism is disposed and whether the pinion is associated with the first gearwheel in, for example, the third or fourth quadrant thereof, the production can be carried out in such a manner that journals for the pinion are provided both to the right and to the left of a central reference plane. The selection of a lefthand or a righthand position for the pinion then takes place only during final assembly when the machine configuration is fixed for a particular customer. The possibility of the selection of a righthand or lefthand pinion position also offers the advantage that a sequential printing mechanism can be incorporated after commissioning of the machine. Although the aforesaid quotient may then change from greater than 1 to equal to or less than 1, or conversely, the pinion can be redisposed free of problems between, for example, the third and fourth quadrants 5 of the first gearwheel.

An embodiment of the present invention will now be more particularly described with reference to the accompanying drawings, in which:

Fig. 1 is a schematic elevation of a rotary printing machine embodying the invention and showing a closed gear train for printing mechanisms of the machine; Fig. 2 is a schematic plan view of the machine, showing a drive thereof; and Fig. 3 is a schematic elevation, to an enlarged scale, of the association of the drive with the gear train in the machine.

Referring now to the drawings, there is sh own a rotary sheetprinting machine of unit mode of construction and in the-variant of four-colour machine, consisting of a sheet feeder 1, a feeder printing mechanism 2, a sequential printing mechanism 3, a drive printing mechanism 4 a delivery printing mechanism 5 and a sheet delivery 6.

If the rotary sheet-printing machine consists of more than four printing mechanisms, these additional printing mechanisms are classed as sequential printing mechanisms.

The printing mechanisms 2 to 5 each comprise an impression cylinder 7, a blanket cylinder 8, a plate cylinder 9 and a transfer cylinder 10.

n, 1 The sheet-guiding cylinders, i.e. impression cylinder 7 and transfer cylinder 10, have gearwheels 11 and 12, wherein the gearwheels 11 and 12 of adjacent cylinders 7 and 10 are disposed in toothed engagement and thus form a closed gear train 13. The gear train 13 is a component of the drive system of the printing machine.

The input of the driving power, which is needed by the machine and is transmitted by way of the gear train 13 to the printing mechanisms 2 to 5, takes place at the drive printing mechanism 4. Drive is supplied by a single-motor drive set 14 to 20 consisting of a motor 14, first and second belt pulleys 15 and 16 and a central wheel 17. The belt pulleys 15 and 16 are connected by a V-belt 20. The central wheel 17..is selectably associated with a righthand driving pinion 18 or with a lefthand driving pinion 19. The pinion 18, when present, is in engagement in the fourth quadrant of the gearwheel 11 of the impression cylinder 7 of the printing mechanism 4 and the pinion 19, when present, is in engagement in the third quadrant of the gearwheel 11. Whether the mechanism 4 is equipped with the righthand pinion 18 or the lefthand pinion 19 is dep ehdent on the position of the mechanism 4 in the machine. When the mechanism 4, in a four- colour machine, is the third printing mechanism (see Fig. 1), the pinion 18 is provided in the fourth quadrant. If the mechanism 4 is the second printing mechanism, the pinion 19 is provided in the third quadrant.

The position of the pinion 18 or 19 at the gearwheel 11 is determined in dependence on the quotient of:

1 k Number of printing mechanisms 2, or 2 and 3, before the drive printing mechanism 4 Number of printing mechanisms 5, or 3 and 5, behind the drive printing mechanism If the quotient is greater than 1, the pinion 18 is arranged in the fourth quadrant and if it is equal to or less than 1, the pinion 19 is arranged in the third quadrant.

Thus, in the example of a seven-colour printing machine in which the drive printing mechanism 4 is arranged as the fifth printing mechanism, the quotient of 4 printing mechanisms before /2 printing mechanisms behind is 2 and it follows from this that the pinion 18 is associated with the gearwheel 11 in the fourth quadrant thereof. In the example of a five-colour printing machine in which the drive printing mechanism 4 is the second printing mechanism, the quotient of 1 printing mechani-sm before /3 printing mechanisms behind is 0.33, and the pinion 19 is thus associated with the gearwheel 11 in the third quadrant thereof.

In the illustrated embodiment, the gearwheel 11, to which drive is supplied, is arranged at the impression cylinder 7 of the mechanism 4. It is, however, feasible for the drive to be fed into the gear train 13 by way of the gearwheel of the transfer cylinder 12. There would be no other conditions in this case in respect of the association of the driving pinions 18 and 19. 20 In addition, in the described embodiment the pinion 18 or 19 is associated selectably in the third or the fourth quadrant of the gearwheel 11 according to the magnitude of the stated quotient, but it is also possible to associate the pinions 18 and 19 selectably with the first and the second quadrants of the gearwheel 11 according to the magnitude of the quotient. The same results can be achieved when the pinion 19 is associated with the gearwheel 11 in the second quadrant instead of the third quadrant, or the pinion 18 with the first quadrant instead of the fourth quadrant.

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Claims

1. A rotary printing machine comprising a plurality of printing mechanisms arranged in succession, a closed gear train comprising a first gearwheel arranged to transmit drive to one of the mechanisms and a plurality of second gearwheels arranged to be driven from the first gearwheel and to transmit drive to the remaining mechanisms, and a pinion drivingly engaging the first gearwheel at a position selected to be dependent on the quotient of the number of mechanisms upstream of said one mechanism divided by the number of mechanisms downstream of said one mechanism.

2. A printing machine as claimed in claim 1, wherein the quotient is greater than 1 and the position is in the fourth quadrant of the first gearwheel.

3. A printing machine as claimed in claim 1, wherein the quotient is equal to or less than 1 and the position is in the third quadrant of the first gearwheel.

4. A printing machine as claimed in claim 1, comprising mounting means for mounting the pinion so that said position is in eitherthe third quadrant of the fourth quadrant of the first gearwheel.

5. A printing machine as claimed in claim 1, comprising a drive gearwheel for driving the pinion, the drive gearwheel being so arranged as to be drivingly engageable with the pinion in either one of two positions thereof.

6. A printing machine substantially as hereinbefore described with reference to the accompanying drawings.

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