JPH10264358A - Ink density automatic regulator for corrugated fiberboard case making machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always obtain a printed surface of predetermined quality irrespective of lapse of time by automatically supplying dilute liquid to a tube of an ink fountain or ink return route so that ink density becomes predetermined density according to a command signal from a densitometer. SOLUTION: Ink liquid is pumped from an ink can 1 by an ink pump 2, and supplied to an ink fountain 4 via an ink supply tube 3. The liquid overflowing from the fountain 4 is returned to the can 1 via a tube 6 of the return route. An ink densitometer 7 always detects viscosity of the liquid of the can 1. When ink density in the can 1 is increased as time is elapsed, the densitometer 7 detects that the liquid becomes predetermined viscosity. Then, the densitometer 7 outputs an operation command signal to a solenoid valve 8 to output dilute liquid from a dilute liquid supply source 9 connected to the valve 8 to the tube 6 of the return route so that the viscosity of the can 1 always become constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexographic printing unit of a cardboard box making machine or an automatic adjusting device for maintaining a constant ink density in an ink circulation device of a cardboard printing machine.

[0002]

2. Description of the Related Art In general, in a flexographic printing unit of a cardboard box making machine or an ink circulating device of a cardboard printing machine, ink is sucked from an ink can and supplied to an ink fountain arranged near an ink roll. The ink overflowing from the ink fountain is returned to the ink can and the ink is circulated again. However, since the flexographic ink has a high quick-drying property, the viscosity of the ink tends to increase with the lapse of time when the ink is recycled. As the ink viscosity increases, the print density increases, causing quality variance between what was printed first and what was printed later.

[0003] For this reason, conventionally, after a certain time has passed, an operator looks at the printed surface of the corrugated cardboard and supplies a diluent to the ink can by experience so that the ink concentration is kept constant. I was

[0004]

However, it is not always possible to eliminate print spots due to the passage of time only by the experience of the operator. Therefore, an object of the present invention is to provide an apparatus that can always obtain a print surface of a constant quality regardless of the passage of time.

[0005]

A densitometer for detecting the ink density of the ink can is provided in an ink fountain or in an ink return path between the ink fountain and the ink can. Further, the above object is achieved by providing a means for supplying a diluting liquid to an ink fountain or a pipe of an ink return path so that the ink concentration becomes a predetermined concentration by a command signal from the densitometer.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing the flow of ink in an ink circulation device of a flexographic printing unit of a cardboard box making machine. An ink can containing a flexo ink liquid, 2 is an ink pump for sucking ink from the ink can 1, 3 is an ink supply pipe, 4 is an ink fountain disposed in front of an ink roll 5, and 6 is the ink fountain. Piping for the ink return path for returning the ink overflowing from the jar 4 to the ink can 1;
Reference numeral 7 denotes a densitometer which detects an ink viscosity in the ink can 1 and outputs an operation command signal to an electromagnetic valve 8.
No. 109612. Reference numeral 9 denotes a diluent supply source connected to the solenoid valve 8.

Normally, the ink liquid is pumped from an ink can 1 by an ink pump 2 and supplied to an ink fountain 4 via an ink supply pipe 3. The ink liquid overflowing from the ink fountain 4 returns to the ink can 1 via the piping 6 in the ink return path. The ink densitometer 7 constantly detects the viscosity of the ink liquid in the ink can 1. Here, when the viscosity of the ink liquid in the ink can 1 increases with the passage of time, the ink densitometer 7 detects this and detects that the viscosity has exceeded a predetermined viscosity. An operation command signal is sent to the solenoid valve 8, and the diluent is supplied from the diluent supply source 9 connected to the solenoid valve 8 to the piping 6 in the ink return path so that the ink viscosity of the ink can 1 is always constant. ing.

Although the present invention has been described with respect to an example in which the ink densitometer and the diluent supply means are directly incorporated in a cardboard box making machine or a cardboard printing machine as described above, the present invention is not limited to this. Needless to say, the ink densitometer and the diluent supply means may be configured as separate units and used in the ink circulation path via this unit.

[0009]

According to the present invention, as described above, the ink viscosity in the ink fountain or the piping of the ink return path is detected, and the diluting liquid is automatically adjusted based on the detected value so that the ink viscosity becomes a predetermined value. Since the ink density is controlled so that the ink density can be controlled very accurately as compared with the conventional one, there is an effect that printing unevenness due to the passage of time is eliminated and a beautiful printed surface is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a main part of an apparatus for implementing the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink can 2 Ink pump 4 Ink roll 5 Ink fountain 7 Ink densitometer 8 Solenoid valve 9 Diluent supply source

Claims (1)

[Claims] 1. An ink circulation device of a flexographic printing unit for sucking ink from an ink can and supplying the ink to an ink fountain disposed near an ink roll and returning ink overflowing from the ink fountain to the ink can. In a corrugated cardboard box making machine, a densitometer for detecting the ink density is provided in the ink return path between the ink fountain or the ink fountain and the ink can, and the ink density is determined by an operation command signal from the density meter. A device for automatically adjusting an ink concentration in a cardboard box making machine, comprising means for supplying a diluting liquid so as to have a predetermined concentration.