JPH0419146A - Damping water apparatus - Google Patents

Abstract

PURPOSE:To effectively attach damping water to a press plate by providing a blower connected to an atomizer, a pair of lips fixed to the end part of a nozzle, and a DC power supply device. CONSTITUTION:Mist atomized by an atomizer 1 is sent into a space surrounded by both a rotating shaft 2 provided with turbine blades 2a and a cover 4 via a duct 6 and discharged by the turbine blades 2a in an amount proportional to the number of revolutions of a plate cylinder 5; therefore, the mist is discharged from a nozzle 12 via a fin at an almost constant flow rate. When the plate cylinder 5 with a press plate 5a adhering to the surface thereof rotates at a high speed, the laminar flow of air on the surface of the press plate 5a is changed to the turbulent flow because crater-like recesses 7c are provided on the inner surface of lips 7 at the upper lip 7a or at the lower lip 7b, so that the mist easily attaches to the press plate 5a. When the mist passes between the press plate 5a and the lip 7b, the press plate 5a is charged to the negative electrode, and the lips 7 to the positive electrode, by a DC power supply device 14. As a result, the mist floating in the vicinity of the press plate and the lips is attracted to each polarity and supplied to the surface of the press plate as damping water.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a dampening water device, and more particularly to a dampening water device that sprays water directly onto a printing plate wound around a plate cylinder of an offset printing press.

[Prior Art] Traditionally, methods for supplying dampening water to printing plates wound around the plate cylinder of offset printing machines can be roughly divided into two methods: water in a water tank is dampened through a plurality of contacting rollers. Two methods have been adopted: a method in which water is supplied, and a method in which water is atomized using an ultrasonic oscillator or a spray device and then the mist is directly supplied to the printing plate. Known examples of methods for generating fog using ultrasonic waves include Utility Model Application No. 50-138104 and Utility Model Application No. 50-13810.
2-131106, JP-A-53-9611, JP-A-5:
3-9613, Japanese Patent Application Laid-Open No. 53-9614, etc., and a known example of a spray type is Japanese Patent Publication No. 49-2924.
There is a first prize.

[Problems to be Solved by the Invention] However, the reason why the practical application of the above-mentioned dampening water supply system has been delayed is as follows.

The ultrasonic type uses the wind pressure of the blower to spray, so the adhesion force is weak (the mist cannot easily adhere to the plate cylinder that rotates at high speed, and the mist concentration distribution varies). In other words, the concentration of fog near the ultrasonic transmitting element is high, and the surrounding area is thinner, making it impossible to generate a uniform fog, which naturally causes variations in the water film that adheres to the surface of the printing plate. To make matters worse, the mist released into the atmosphere not only caused the frame of the printing machine to rust (but also dampened the printing paper, increasing the tension of the printing paper and causing excessive drying in the dryer). The disadvantage was that it imposed a heavy load.

Furthermore, when the plate cylinder rotates at high speed, a laminar flow is formed near the surface layer of the printing plate adhered to the surface of the plate cylinder, resulting in the adhesion of fog, which means that dampening water cannot effectively adhere to the printing plate. Ta.

The present invention has been made in view of the above-mentioned problems, and its purpose is to electrostatically attach mist atomized by an atomizer to a printing plate wound around a plate cylinder of an offset printing machine. An object of the present invention is to provide a dampening water device which is characterized by supplying dampening water.

Furthermore, it is an object of the present invention to provide a lip that generates turbulence in the laminar flow of the surface layer of a printing plate adhered to the surface of a printing plate that is generated during high-speed rotation of the printing cylinder, and that facilitates the adhesion of mist.

[Means for Solving the Problems] The present invention has the following means for solving the above-mentioned problems of the invention. The basic configuration of the present invention is described in the following items 1 to 4.

(1) In a dampening water device that supplies dampening water to a metal printing plate wound around a plate cylinder, an atomizer for atomizing the supplied water.

(bl: a blower device connected to the atomizer and blowing the mist; (cl: a blower device connected to the blower device and guiding the mist to the circumferential surface in the longitudinal direction of the printing plate attached to the plate cylinder); (d) a metal member fixed to the end of the nozzle, extending in the vertical direction of the axis of the printing plate of the printing cylinder, and having an arc-shaped side surface with a predetermined gap from the printing plate of the printing cylinder; and (fe) a DC power supply device that loads a DC voltage using the pair of lips and the printing plate of the plate cylinder as electrodes, respectively.

It was composed of

(2) A humidity sensor is provided to detect the humidity near the nozzle or lip, and the amount of atomization by the atomizer or the amount of air blown by the blower is controlled based on the humidity signal from the humidity sensor.
A control device is provided to maintain the temperature within the nozzle portion and the lip portion within a predetermined range.

(3) The lip consists of an upper lip fixed to the duct and a lower lip.

(4) Crater-shaped circular recesses were formed regularly or irregularly in the lip.

(5) The lip was provided with a plurality of parallel grooves each having an arcuate cross section in the same direction as the longitudinal direction of the plate cylinder axis.

[Function] The "dampening water device" of the present invention functions as described below.

The mist atomized by the atomizer passes through a duct and is accelerated by the rotation of the rotating shaft of the wing surface material, and is sent through the rectangular nozzle of the cylindrical cover to the printing plate and lip wound on the plate cylinder. A fog is introduced between the two. Furthermore, a capacitor is formed using the printing plate and the lip as electrodes, and the mist is adsorbed to the printing electrode to form a uniform water film on the printing plate.

A humidity sensor is provided, and the amount of atomization by the atomizer or the amount of air blown by the blower can be controlled based on the humidity signal from the humidity sensor, thereby maintaining the humidity within the nozzle portion and the lip portion within a predetermined range.

When the plate cylinder rotates at high speed, a laminar air flow is formed on the surface layer of the printing plate, which acts to prevent fog from adhering to the plate.

Therefore, due to the crater-shaped recesses or arc-shaped grooves formed on the inner surface of the lip, the laminar flow in the surface layer of the printing plate changes to a turbulent flow, and mist tends to adhere to the surface of the printing plate.

L Example] A first example of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing one embodiment of a dampening water device that supplies dampening water to a printing plate wound around a plate cylinder of an offset printing press. FIG. 2 is a sectional view taken along the line AA in FIG. 1.

l is an atomizer for atomizing the supplied water;
The method mixes pressurized water and compressed air and atomizes the mixture. Note that an atomizer (not shown) that atomizes water using an ultrasonic oscillator may be used.

2 is a rotary shaft rotatably supported on a frame at both ends and has turbine blades 2a formed in the axial direction; 3 is a variable motor that rotationally drives the rotary shaft 2 via a belt 3a; 4 is a rotary shaft 2
It is a rectangular supply device that surrounds the cover 4, is arranged parallel to the plate cylinder 5 on which the printing plate 5a is wound, has a nozzle 12 in the axial direction, and guides the mist supplied from the atomizer l in the axial direction of the cover 4. Mouth 4a
6 is a duct connecting the cylindrical cover 4 and the atomizer 1.

Reference numeral 7 is provided at the end of a nozzle 12 provided on a cylindrical cover 4, and the cylindrical portion in the axial direction of the plate cylinder 5 is arranged at a predetermined interval along the curvature of the plate cylinder 5 to pivot the printing plate 5a in a non-contact manner. The lip consists of an upper lip 7a and a lower lip 7b fixed so as to partially surround it in the direction, and the upper lip 7a plays the role of the minimum necessary cover to prevent the mist discharged from the duct 6 from escaping to the outside. Furthermore, as shown in the cross section of FIG. 4, the upper lip 7a or the lower lip 7b has crater-shaped circular recesses 7C formed regularly or irregularly.

As shown in FIG. 5, instead of the crater-shaped circular recess 7C, a plurality of parallel grooves 7d each having an arcuate cross section in the same direction as the axial direction of the plate cylinder may be provided in the lower groove 7b. A plurality of recessed grooves are formed in the vertical direction. As shown in FIG. 3, the fins 8 that adjust the flow of
A lever 8 is provided on the upper part of the shaft 8b.
a is fixed.

Therefore, by manually rotating the lever 8a, the flow of the mist can be changed and the humidity concentration can be adjusted to be uniform. 9a is a suction duct that sucks mist close to the plate cylinder 5 and the rectangular nozzle 12 or lip;
A is provided with a suction device 9 that operates a suction duct. 1
3 is a humidity sensor set at the outlet of the duct, and if a plurality of humidity sensors are arranged in the longitudinal direction of the duct, it is possible to detect humidity unevenness in the longitudinal direction.

Reference numeral 10 denotes a sensor 11 that detects the rotation speed of the plate cylinder 5, and is a control device that controls the rotation speed of the rotating shaft 2 to a rotation speed proportional to the rotation of the plate cylinder 5 based on the detected speed signal.

Next, the operation of this device will be described.

First, the rotational speed of the first plate cylinder 5 is detected by the rotation sensor 11, and a predetermined rotational speed proportional to the rotation of the plate cylinder is selected as the rotational speed of the variable motor 3, and the rotating shaft 2 is rotated via the belt 3a. drive On the other hand, the atomized mist is sent by the atomizer 1 via a duct 6 into a space surrounded by a rotary shaft 2 equipped with a turbine blade 2a and a cover 4, and the turbine blade 2a rotates the plate cylinder 5. The amount of mist proportional to the number of mist is discharged from the nozzle 12 via the fins 8 at a substantially constant flow rate. The plate cylinder 5 with the printing plate 5a attached to its surface rotates at high speed (
When the printing plate 5a is rotated at a speed of about 1000 rpm or more), air and laminar flow are formed on the surface layer of the printing plate 5a, which acts to prevent the adhesion of mist.

However, as shown in FIG. 4, the inner surface of the lip 7 has a crater-shaped recess 7c (with a diameter of 2 to 3 mm) on the upper lip 7a.
Alternatively, since the laminar flow on the surface layer of the printing plate 5a changes to a turbulent flow and a large number of vortices are generated in the concave portions 7d since it is provided on the lower lip 7b), mist tends to adhere to the printing plate 5a, and dampening water flows. Can be supplied.

When the mist passes between the printing plate 5a and the lip 7b, the Al1 printing plate 5a is charged to one pole by the DC power supply 14, and the Al
The lip 7 made by No. 1 is charged with ten poles, and the mist near the lip 7 is attracted to each polarity and supplied to the surface of the printing plate as dampening water. On the other hand, the mist that is not absorbed by the printing plate 5a and the pair of upper and lower lips 7 and the water droplets that adhere to the surface of the lip 7 are sent to the mist collection device 9 via the suction duct 9a along the grooves 78 formed in the longitudinal direction of the lip 7. It will be collected.

Since a humidity sensor 13 is provided inside the nozzle 12, the amount of atomization of the atomizer or the amount of air blown by the blower is controlled based on the humidity signal from the humidity sensor, thereby controlling the humidity inside the nozzle portion and the lip portion. can be maintained within a predetermined range.

[Effects of the Invention] As described above, the present invention has the following effects.

The printing plate wound around the plate cylinder of an offset printing machine is atomized by an atomizer, accelerated by a rotating shaft, and supplied between the lip surface and the printing plate, and the mist is electrostatically deposited. A uniform water film can be formed on the printing plate.

In contrast to the laminar flow of the surface layer of the printing plate adhered to the surface of the plate cylinder 5 that occurs while the plate cylinder 5 rotates at high speed, turbulent flow is generated by the many crater-shaped recesses or the many grooves provided in the lip. In addition, since the suction is performed by static electricity, the mist can be uniformly and effectively adhered to the printing plate.

After the mist discharged from the slit-shaped nozzle adheres to the printing plate, excess mist is collected, so the printing press body does not rust and the printing paper does not become damp.

[Brief explanation of the drawing]

1 to 5 are diagrams showing embodiments of the present invention. FIG. 1 is a plan view of the dampening device, and FIG. 2 is a cross-sectional view taken along the line A--
3 is a perspective view showing a plurality of fins provided on the nozzle, FIG. 4 is a plan view showing the inner wall of the lip with a crater-shaped recess, and FIG. 5 is an arc-shaped groove. The cross-sectional views showing the cross-sectional shapes of the lips formed therein are shown respectively. 1: Atomizer, 2: Rotating shaft forming turbine blades, 3:
variable motor, 4: cylindrical cover, 5: plate cylinder, 6: duct, 7: lip, 7a: upper lip, 7b: lower lip, 7c: recess, 7d: groove, 8: fin, 9: suction device,
9a: recovery duct, 10: control device, 11: sensor,
12: Nozzle.

Claims (5)

[Claims] (1) In a dampening water device that supplies dampening water to a metal printing plate wound around a plate cylinder, (a) an atomizer for atomizing the supplied water; (b)
(c) a nozzle connected to the atomizer to blow the mist; (c) a nozzle connected to the blower to guide the mist to the peripheral surface in the axial direction of the printing plate attached to the plate cylinder; (d) a pair of metal parts fixed to the end of the nozzle, extending in the axial direction of the printing plate of the printing cylinder, and having arcuate sides arranged with a predetermined gap from the printing plate of the printing cylinder; and (e) a DC power supply device that loads a DC voltage using the pair of lips and the printing plate of the plate cylinder as electrodes, respectively. (2) A humidity sensor is provided to detect the humidity near the nozzle part or the lip part, and the atomization amount of the atomizer or the airflow rate of the blower is controlled based on the humidity signal from the humidity sensor. 2. The dampening water device according to claim 1, further comprising a control device for controlling the humidity within the dampening device within a predetermined range. (3) The dampening water device according to claim 1, wherein the lip consists of an upper lip fixed to the duct and a lower lip. (4) The dampening water supply device according to claim 3, wherein the lip has crater-shaped circular recesses formed regularly or irregularly. (5) The dampening water device according to claim 3, wherein the lip is provided with a plurality of parallel grooves each having an arcuate cross section in the same direction as the longitudinal direction of the axis of the plate cylinder.