JPH0342184B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an ink supply timing control method for a rotary printing press.

Prior Art A rotary printing press is configured such that a plate cylinder and an impression cylinder are arranged facing each other, and a printing plate is wound and fixed around the plate cylinder, and an ink roll is brought into pressure contact with the printing plate to form an ink film on the printing plate surface. The desired printing is performed on a sheet of paper or the like that passes between the plate cylinder and the impression cylinder.

Problems to be Solved by the Invention By the way, in a flexo printing machine for multicolor printing equipped with a plurality of printing blocks each consisting of a plate cylinder and an impression cylinder,
Generally, quick-drying inks are used. in this case,
In a structure in which the ink roll is constantly pressed against the plate cylinder, the following drawbacks are pointed out. In other words, when preparing to operate a printing press, if the plate cylinder is rotated without first feeding a sheet, the quick-drying ink will be transferred from the ink roll to the plate cylinder multiple times, and excess ink will be transferred to the printing plate surface. become. If you start feeding sheets in this state, serious problems will occur, such as printing becoming unclear in the initial stage of feeding, or ink clogging in the engraved recesses of the printing plate, making it unusable. .

Therefore, in order to deal with this problem, instead of the structure in which the ink roll is in pressure contact with the plate cylinder at all times, the ink roll is in pressure contact with the plate cylinder only while paper is being fed, and at other times the ink roll is in pressure contact with the plate cylinder. A mechanism has been proposed in which the roll is separated from the plate cylinder.
In this method, a timer is used to set a predetermined time delay based on when paper feeding starts and when paper feeding stops, and in response to this, the ink roll is brought into contact with and separated from the plate cylinder. However, due to uncertain factors such as changes in paper feeding speed and errors in timer accuracy, the timing of pressing and separating the ink rolls is not always constant, and problems such as printing defects are still not completely resolved. The current situation is that this is not the case.

Purpose of the Invention The present invention has been proposed in order to suitably overcome the problems inherent in the prior art. The optimal timing for separating the ink roll from the plate cylinder when the paper feed stops is determined by a sensor placed in front of the print contact point by the arc length of the plate cylinder from the ink roll contact point to the so-called print contact point. To perform clear printing without waste from the start of printing to the end of printing, and to eliminate multiple transfers of ink to the printing plate and clogging of ink in the grooves of the printing plate.

Means for Solving the Problems In order to overcome the above problems and achieve the intended purpose, an ink supply timing control method according to the present invention includes a plate cylinder and an impression cylinder arranged opposite each other, and a method for transferring ink to the plate cylinder. and an ink roll configured to press the ink roll against and separate from the plate cylinder by energizing the ink roll drive source in response to the start and stop of sheet supply from the sheet supply device. In a printing press, find the arc length in the plate cylinder rotation direction from a contact point where the plate cylinder presses against the ink roll to a printing contact point located at the bottom dead center where the plate cylinder closely faces the impression cylinder. , a sensor is provided facing a reference point located on the supply path of the sheet coming from the sheet supply device and located in front of the printing contact point by a dimension corresponding to the arc length, and first from the sheet supply device. The sensor detects that the front end of the supplied sheet passes the reference point, and an ink roll pressure contact command is given to the ink roll drive source via the electric control circuit, thereby causing the ink roll to move to the The ink roll drive source is brought into pressure contact with the plate cylinder, and the sensor detects that the trailing edge of the last sheet fed from the sheet feeding device passes through the reference point, and the ink roll drive source is controlled via an electrical control circuit. The present invention is characterized in that an ink roll separation command is given to the ink roll, thereby controlling the ink roll to be separated from the plate cylinder.

Embodiments Next, a preferred embodiment of the ink supply timing control method for a rotary printing press according to the present invention will be described below with reference to the accompanying drawings. 1st
The figure schematically shows the roll arrangement of a rotary printing press in which the method according to the invention is preferably used.
In this example, two corrugated sheets of predetermined dimensions are
The present invention assumes a flexographic printer slotter that performs color flexographic printing, followed by crease processing and slot processing. However, the use of the method according to the invention is not limited to this type of corrugated board printing press.

Prior to explaining the contents of the present invention, in order to facilitate understanding, the main components of the illustrated flexographic rotary printing press will be briefly explained. A plate cylinder 12 and an impression cylinder 14 are rotatably disposed on a machine base designated by reference numeral 10, and a rubber stamp plate (not shown) is wound and mounted around the plate cylinder 12. An anilox roll 16 (hereinafter referred to as an ink roll) is disposed adjacent to the plate cylinder 12,
It is designed so that it can be pressed against and separated from the plate cylinder 12 (the specific structure will be described later in connection with FIGS. 3 and 4). A rubber roll 18 is disposed in close contact with the ink roll 16, and quick-drying flexographic ink is supplied from above between both rolls 16 and 18.
The ink is transferred to the printing plate via an ink roll 16.

The corrugated cardboard sheets 22 stacked on the sheet feeding device 20 are transported by a carrier 24 that reciprocates back and forth.
The paper is caught and pushed forward by a pair of upper and lower paper feed rollers 26, and sent to the printing block.
Printing is performed by passing between the plate cylinder 12 and the impression cylinder 14 under pressure. Since the embodiment is a two-color printing press, a first printing section 28 and a second printing section 30 having exactly the same configuration are arranged in series.

The power is provided by a motor 32 installed at the bottom of the machine 10.
is transmitted to the lower paper feed roller 26 via the V belt 34, and from the lower paper feed roller 26 to each plate cylinder 12 of the first printing section 28 and the second printing section 30 via a gear train (not shown). Power is transmitted to other rotating rollers. Further, the kicker 24 is an appropriate crank mechanism connected to the rotating system (for example, as shown in FIG. 2, a crank rod 35 connects the rocker arm 33 rocked by an eccentric cam disc 31 and the kicker 24). It is configured to perform non-uniform reciprocating motion via the Then, the pusher 24 pushes out the corrugated cardboard sheets 22 stacked with the front and back sandwiched between the front gate 36 and the backstop 38 provided in the sheet feeding device 20 in order from the bottom. In FIG. 1, reference numeral 40 indicates a creaser portion, and numeral 42 indicates a slotter portion.

A lifting mechanism for the ink roll 16 is shown in FIG.
In FIG. 3, the ink roll 16 and the rubber roll 18 are rotatably supported by brackets 44 at both ends thereof. The rubber roll 1
The shaft 46 of the double-acting air cylinder 50 is pivotally connected to the machine base 10, and the bracket 44 is pivotally connected via a clevis 54 to a piston rod 52 of a double-acting air cylinder 50 which is suspended and pivotally supported on the fixed support part 48. Therefore,
When the air cylinder 50 is energized, the ink roll 16 rotates around the shaft 46 as shown in FIG.
is separated from the plate cylinder 12 (dotted line position), and when reversely biased, it comes into pressure contact with the plate cylinder 12 as shown by the solid line.

In the rotary printing press having the above-described structure, the present invention sets the timing at which the ink roll 16 is brought into contact with and separated from the plate cylinder 12 from the contact point where the plate cylinder 12 comes into contact with the ink roll 16. The content is to appropriately control based on the arc length in the rotational direction of the plate cylinder up to the bottom dead center, which is the position closest to and facing the impression cylinder 16. explain.

FIG. 5 is a partially enlarged view of the printing block and sheet feeding device shown in FIG.
6 contacts the plate cylinder 12, and the so-called sheet printing contact point b, which is the bottom dead center where the plate cylinder 12 faces the impression cylinder 14 in close proximity to each other, rotate about the central axis of the plate cylinder 12. Assume that the phase angle in the direction is 145° and the circumference of the plate cylinder 12 is 1400 mm (since the printing plate is wrapped around the printing cylinder 12, the circumference will change somewhat when the printing plate is mounted. However, this can be safely ignored). Note that this set dimension is the same as that of the first printing block 2.
8 and the second printing block 30 are completely identical.

Then, when considering the timing to bring the ink roll 16 into pressure contact with the plate cylinder 12 when feeding the corrugated sheet 22, the contact point a ( This is the starting point of ink transfer to the printing plate) when it rotates 145 degrees and reaches the printing contact point _b1 , from the sheet feeding device 20 to the printing plate 2.
4, the timing may be set in advance so that the front end of the corrugated paperboard sheet 22, which is sent out first, also arrives at the printing contact point _b1 and coincides with the ink transfer starting point. For example, in this embodiment, the phase angle of the plate cylinder 12 is 145 degrees, so the plate cylinder 12
The length of the circular arc _A1 in the plate cylinder rotation direction from the ink roll contact a to the print contact _b1 is determined by the circumference x 145°/360° (1400 mm x 145°/360°) and is approximately 564 mm. . In other words, the ink roll 16 and the plate cylinder 12
Since the ink roll contact a that contacts with is located 564 mm in front of the printing contact _b1 ,
In the end, the ink roll 16 can be brought into pressure contact with the plate cylinder 12 at the point when the front end of the corrugated paperboard sheet ₂₂ reaches point _c1 , which is 564 mm before the printing contact point b1.

Further, the timing at which printing of a series of corrugated sheets 22 is finished and the ink roll 16 is separated from the plate cylinder 12 according to the ordered quantity is analyzed as follows. That is, in this case, when the ink transfer end point on the plate cylinder 12 when the ink roll 16 is separated from the plate cylinder 12 rotates 145 degrees and reaches the printing contact point _b1 , the last corrugated cardboard sheet 22 The rear end also reaches the printing contact point,
The timing is set to match the ink transfer end point.

Ultimately, in order to press the ink roll 16 into contact with and separate from the plate cylinder 12, the front end of the first corrugated sheet to be supplied must be placed in front of the printing contact b ₁ by the length of the arc A ₁ . A solenoid is connected to a drive source for the ink roll 16, such as a double-acting air cylinder 50, by detecting the passage of the paperboard sheet and the passage of the rear end of the corrugated paperboard sheet fed last.
All you have to do is give a signal to each SOL and control its operation. Although the explanation has focused on the first printing block 28 that prints the first color, the second printing block 3 that prints the second color
The case of 0 is exactly the same, and the arc A 2 from the ink roll contact a to the printing contact b ₂ of the second plate cylinder 12 _is
2 points C are found in front of the printed contact B ₂ by the length (=564 mm).

Next, a preferred configuration for implementing the timing control method according to the present invention is illustrated in FIG. 6 and will be described. In FIG. 6, only the first printing block 28 is shown, and on the linear sheet feeding path 56 connecting the tip of the sheet feeding device 20 and the printing contact point _b1 , there is a circular arc from the printing contact point _b1 . The reference point c ₁ is located in front of you by the length of A ₁ (564 mm). As described above in connection with FIG. 5, when the front end of the first corrugated sheet 22 passes through this reference point _c1 , this is detected and the ink roll 16 is brought into pressure contact with the plate cylinder 12; Also, when the rear end of the last corrugated sheet 22 passes through the reference point _c1 , this is detected and the ink roll 16 is moved to the plate cylinder 12.
Separate from.

Detection of passage of the end of the corrugated board sheet ₂₂ at this reference point c1 is preferably performed by an optical sensor comprising a light emitting element and a light receiving element. That is, a light emitting element 58 made of, for example, a light emitting diode (LED) and a light receiving element 60 made of a phototransistor are arranged facing each other at the position of the reference point c ₁ , and a light emitting path of 58.60 mm between the two elements is arranged as a sheet. 22
The structure may be configured to detect the passage of an object based on the voltage change in the light receiving element when the object passes and blocks light.

The sensors 58 and 60, each consisting of a light emitting element and a light receiving element, are connected to a control circuit 66 that controls electrically the rotary printing press of this type. and,
When the sensors 58 and 60 detect that the front end of the sheet 22 first fed from the sheet feeding device 20 passes the reference point _c1 , the An ink roll pressure contact command is given to the solenoid SOL connected to the dynamic air cylinder 50. As a result, the ink roll 16 is brought into pressure contact with the plate cylinder 12. Also, the sheet 22 supplied last from the sheet supply device 20
When the sensors 58, 60 detect that the rear end passes the reference point _c1 , an ink roll separation command is given to the solenoid SOL via the electrical control circuit 66. This causes the ink roll 16 to be separated from the plate cylinder 12. It is recommended that an optical fiber type photoelectric switch be used as the optical sensor to be incorporated into a rotary printing press with limited space as in this embodiment. This has many advantages, such as having a small detection section, being resistant to shock and temperature changes, and being unaffected by external induced noise.

In this way, when the front end of the first corrugated sheet 22 passes between the light emitting element 58 and the light receiving element 60 and blocks light, and when the last corrugated sheet 22
When the rear end of 2 completely passes through the light projection path and the light blocking stops, the ink roll 16 is pressed against and separated from the plate cylinder 12, respectively.
One problem remains. This is because once the printing of a corrugated sheet is started, the ink roll 16 must remain in pressure contact with the plate cylinder 12 until the printing of the last corrugated sheet is completed (the last (The ink roll 16 separates from the plate cylinder 12 after printing of one sheet is completed.) Since the corrugated cardboard sheets 22 that are sequentially supplied are discontinuous plates, each sheet passes through the light projection path of the optical sensor. Each time the light is interrupted, the light is interrupted and its recovery is repeated, and a command signal for pressing and separating the ink roll 16 is transmitted from the optical sensor to the solenoid SOL, which causes chattering if left unchecked.

To prevent this, an ink roll pressure contact command is issued when the first sheet starts passing through the projection path.
Various means can be proposed to cause the ink roll separation command to be issued upon completion of passage of the last sheet through the light projection path. For example, a control circuit (not shown) controls the order quantity of corrugated sheets.
After issuing an ink roll pressure contact command when feeding the first sheet, the optical sensor operation is held and the order quantity is counted down, and when the last sheet is reached, the optical sensor is turned off. The ink roll separation command may be issued by restoring the operation of the sensor and detecting the passage of the rear end of the last sheet.

Note that when the ink roll 16 is brought into pressure contact with the plate cylinder 12, it is desirable to bring the ink roll 16 into pressure contact with the plate cylinder 12 a little earlier, and conversely, when the ink roll 16 is separated from the plate cylinder 12, it is desirable to separate it a little later. Therefore, as shown in FIG.
An optical sensor 62 for a separation command and an optical sensor 64 for a pressure contact command are installed independently on the left and right sides of the reference point _c1 , respectively, so as to transmit an earlier or later command signal by a desired time. It is preferable to configure this.

Effects of the Invention As described above, according to the method of the present invention, when the first corrugated sheet is started to be fed and its front end reaches the printing contact, the ink transfer starting point on the plate cylinder also reaches the printing contact. The ink transfer end point on the plate cylinder reaches the printing contact point when the two arrived matches and when the last sheet of the ordered quantity has been printed and the trailing edge of the first sheet reaches the printing contact point. Since the timing of press contact and separation of the ink roll from the plate cylinder is precisely controlled so that the two match, there is no problem such as multiple transfer of ink to the printing plate or ink clogging in the depressions of the printing plate. is completely eliminated, and it is possible to print clearly and without waste from the first sheet to the last sheet.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a roll arrangement of a rotary printing press in which the method according to the present invention is suitably carried out, and FIG. 2 is a schematic side view of a paper feeding mechanism used in the printing press shown in FIG. , FIG. 3 is a perspective view schematically showing the ink roll lifting mechanism, FIG. 4 is a schematic diagram showing the operating state of the mechanism shown in FIG. 3, and FIG. 5 is a perspective view of the printing block shown in FIG. 1. FIG. 6 is a schematic enlarged view showing a state in which the ink roll approaches and moves away from the plate cylinder at a phase angle of 145°, and FIG. 6 shows a preferred example for carrying out the method according to the present invention. FIG. 7 is a schematic illustration of another preferred embodiment for carrying out the method according to the invention. 12... Plate cylinder, 14... Impression cylinder, 16... Ink roll, 20... Sheet supply device, 22... Corrugated board sheet, 50... Ink roll drive source (air cylinder), 58... Sensor (light emitting element) ), 60...
...Sensor (light receiving element), 66...Electrical control circuit.

Claims (1)

[Claims] 1. A plate cylinder 12 and an impression cylinder 14 arranged opposite each other, and an ink roll 1 that transfers ink to the plate cylinder 12.
6, the sheet 2 from the sheet feeding device 20
In the rotary printing press configured to energize the ink roll drive source 50 in response to the start and stop of supply in accordance with No. 2, and press the ink roll 16 against and away from the plate cylinder 12, the plate cylinder 12 is From contact points a ₁ and a ₂ in pressure contact with the ink roll 16 to a printing contact point located at the bottom dead center where the plate cylinder 12 faces the impression cylinder 14 in close proximity.
Arc length A ₁ in the plate cylinder rotation direction up to b ₁ and b ₂ ,
A ₂ is determined on the supply path of the sheet 22 coming from the sheet supply device 20 and at the printing contacts b ₁ , b ₂
The sensor 58 faces the reference points c ₁ and c ₂ located in front by a dimension corresponding to the arc lengths A ₁ and A ₂ .
60 is provided, and the sensors 58 and 60 detect when the front end of the sheet 22 first fed from the sheet feeding device 20 passes through the reference points c ₁ and c ₂ , and the electrical control circuit 66 is activated. An ink roll pressure contact command is given to the ink roll drive source 50 through the ink roll drive source 50, whereby the ink roll 16 is brought into pressure contact with the plate cylinder 12, and the rear end of the sheet 22 that is last supplied from the sheet supply device 20 is The sensors 58 and 60 detect passing through the reference points c ₁ and c ₂ and give an ink roll separation command to the ink roll drive source 50 via the electrical control circuit 66, thereby causing the ink roll to move. 16 is controlled so as to separate the plate cylinder 12 from the plate cylinder 12.