JPH05193104A - Automatic film thickness controlling screen printing machine - Google Patents

Abstract

PURPOSE:To carry out effective automatic control of film thickness in screen printing for thick film products. CONSTITUTION:The subject machine is composed of a stepping motor for changing angles for a squeegee, an encoder mechanism A which detects the angle of the squeegee, a cylinder mechanism 3 which makes the pressure for pushing-in of the squeegee constant, a displacement gauge B for measuring film thickness and a CPU which processes signals.

Description

Detailed Description of the Invention

[0001]

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to automatic control of film thickness of a screen printing machine for thick film products.

[0003]

2. Description of the Related Art A screen printing machine is generally used for manufacturing conventional thick film products, and one of the factors controlling the performance of thick film products is film thickness.

In order to make this film thickness constant, the printing conditions such as the amount of pushing in the stage are determined so that the target film thickness is obtained by the trial printing before the main printing, and after the determination, the printing conditions are the same until the next setup is changed. Printing is performed under the conditions.

[0005]

However, when printing is performed under the same conditions as described above, the film thickness of the product to be printed changes due to fluctuations in external factors such as ink viscosity during printing for a long time. To cope with this film thickness fluctuation, the ink viscosity during printing is finely controlled and the film thickness standard is expanded.

However, since it is difficult to control the ink viscosity during printing, it is difficult for the current printing system to cope with the fluctuation of the film thickness, and it takes a long time to carry out a test printing for determining printing conditions. is there.

SUMMARY OF THE INVENTION The present invention has a technical object to provide an automatic film thickness control device capable of coping with fluctuations in film thickness in a printing system of a screen printing machine.

[0008]

[Constitution of the invention]

[0009]

The technical means for solving the problems are as follows.

In a screen printing machine comprising a screen, a squeegee, and a squeegee driving mechanism, a stepping motor for changing the squeegee angle, an encoder mechanism for detecting the squeegee angle, a cylinder mechanism with a constant squeegee pushing pressure, and a film thickness. The squeegee angle is automatically set from the empirically obtained calibration curve, and the target film thickness is automatically maintained by performing feedback control, and the film thickness is maintained for a long time. It is an automatic film thickness control screen printing machine characterized by suppressing fluctuations in thickness.

[0011]

[Function] A fixed film thickness on the screen (target: 15μ)
In the case of printing m), the squeegee sets the optimum pressure for pressing the screen with a constant pressure for printing, and if the constant pressure is always maintained, the optimum film pressure can be printed.
For that purpose, set the squeegee angle with the encoder,
Next, even if the squeegee angle is changed, the pressure from the air cylinder or hydraulic cylinder is constant, so the specified film thickness can be printed, and this film thickness can be measured with a displacement meter (in the case of non-contact, measured with laser light). The squeegee actuator is instructed by a film thickness difference from the target film thickness by the CPU, and the squeegee angle is increased or decreased, and this is constantly repeated to keep the film thickness constant and the target film. A thickness of 15 μm can be achieved.

[0012]

EXAMPLES Examples will be described below.

FIG. 1 shows a squeegee actuator of the present embodiment, where 1 is a stepping motor for varying the angle of a squeegee 4, 2 is an encoder for setting the squeegee angle, and 3 is an air cylinder. Is.

The operation of the above structure will be described below.
When the squeegee angle is changed during printing, the distance between the screen and the squeegee rubber changes in a conventional printing machine, which causes a change in the printing film thickness or a shading.

However, in this embodiment, when the squeegee angle changes, the pressing force changes downward due to the action of the air cylinder 3 and printing can be performed with a preset optimum printing pressure to form a constant film thickness.

When the ink material hardens due to a change in environment and the film thickness changes, the measured value of the film thickness which is constantly measured by the displacement meter is sent to the CPU as a signal, and the predetermined squeegee angle and film are measured. The target film thickness can be immediately formed by comparing the calibration curves having the relationship with the thickness, operating the stepping motor, changing the angle of the squeegee, and printing with a constant printing pressure.

FIG. 3 is a system diagram of the present invention. In FIG. 3, the film shape of the printed product is measured by the non-contact displacement meter (laser light) of B immediately after printing.

For the measurement data, the film thickness is calculated by C, and the next squeegee angle is calculated from the calibration curve. Then, the squeegee of A is driven. After that, by repeating this, the setup time can be reduced and the fluctuation of the film thickness can be suppressed.

FIG. 2 shows this printing operation algorithm.
The operation in the case of performing printing in this example is that after printing one sheet, the film thickness is measured, and a calibration curve prepared in advance from data obtained by various experiments from the ink material, film thickness, squeegee angle and printing pressure is used. The squeegee angle for the next printing is determined based on the original value, the squeegee angle is set again, and the next printing is performed. After that, this process can be repeated to immediately suppress the fluctuation of the film thickness.

FIG. 4 shows a control block diagram during printing. The flow of control is that after printing, the film shape is measured with a displacement gauge, the squeegee setting angle is determined next time, and the squeegee is driven to print.

At this time, the current film thickness is calculated at the portion A in the figure, but by performing this part by the method described below, it is possible to cancel small variations in the current film thickness due to variations in individual film thicknesses, and to obtain long-term results. It is possible to extract only the film thickness variation.

The main film thickness calculation methods are as follows.

(1) The average film thickness for the past 2 to 10 times is calculated.

(2) The film thickness is calculated by weighting the past two to ten times of data (adding a coefficient depending on the elapsed time after printing).

(3) The film thickness is calculated using the PID control (using the change in the inclination of the thick film) on the data of the past several times.

In the above embodiment, the case where the squeegee actuator is constructed by using the stepping motor, the encoder and the CPU in order to accurately change the squeegee angle has been described. However, the squeegee angle can be accurately changed. I wish I had it.

Further, the air cylinder used for printing at a constant printing pressure may be a hydraulic cylinder as long as it has a constant pressing pressure.

The displacement gauge may be a non-contact type or a tactile type.

[0029]

[Effect] The present invention has the following effects. In other words, the setup and trial printing work time was about 30 minutes in the past, but now it will be finished in about 1 minute, and even if printing is performed for a long time, the film thickness is automatically maintained to maintain the target film thickness. Thickness variation 2
It can be reduced to / 3 to 1/2.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a squeegee actuator of this embodiment.

FIG. 2 is a flow chart of the control algorithm of this embodiment.

FIG. 3 is a system diagram showing a signal flow for automatic film thickness control.

FIG. 4 is a control block diagram.

[Explanation of symbols]

 1 Stepping Motor 2 Encoder 3 Air Cylinder 4 Squeegee 5 Screen A Encoder Mechanism B Displacement C CPU

Claims (1)

[Claims] 1. A staring machine comprising a screen, a squeegee and a squeegee driving mechanism, a stepping motor for changing the squeegee angle, an encoder mechanism for detecting the squeegee angle, and a cylinder mechanism for keeping the squeegee pushing pressure constant. , A film thickness automatic control screen printer that has a displacement meter to measure the film thickness and a CPU to process the signal, automatically sets the stage angle from the calibration curve, and automatically maintains the target film thickness by performing feedback control. ..