JPH1148442A - Automatic screen printing device for glass printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic screen printing device for glass printing, which is capable of detecting troubles, such as damaging, breakage and the like, in a screen printing frame quickly and automatically. SOLUTION: An automatic screen printing device for glass printing is provided with a mounting table 1, on which a printing base board 2, having a screen printing frame 3 equipped with a vertical moving means 6, is put, and a movable scraper 4, capable of pushing out ink through the screen until the same passes through the lower part of the printing frame. Optical monitoring devices 9, 10 are arranged in a space A positioned between the printing base board 2 and the lower part of a frame for printing while the optical monitoring devices are connected to an evaluation circuit, capable of intercepting the printing operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of extruding ink through a screen until a printing board having a screen printing frame provided with a vertical moving means is placed thereon and passing through a lower portion of the printing frame. The present invention relates to an automatic screen printing apparatus for glass printing including a movable scraper.

[0002]

BACKGROUND OF THE INVENTION (Silk) screen printing technology is widely used for the production of automotive glass. For example, in the production of electrically heatable rear windows,
Each is equipped with a dryer to print the decorative window frame using opaque ink for heating while using a conductor heating system with conductive screen ink, and is placed one behind the other on the production line. Two automatic screen printing devices are required.

In order to mass produce printed glass on an industrial scale, an automatic screen printing apparatus is generally used.
With this device, the entire printing cycle, including the steps of moving, positioning and lowering the screen mold, printing with the movement of the scraper, lifting the screen printing frame, transporting it to the dryer, and spreading with the movement of the scraper, is controlled electronically. This is done automatically using the device.

[0004] In practice, there must be an operator for each area of each automatic screen printing device to be able to intervene in the event of a trouble even though the printing process proceeds automatically.

[0005] In particular, troubles that can damage the screen printing frame due to wear or broken pieces of glass, if not detected immediately, can result in lost productivity and, in some circumstances, large repair costs. This is because the screen ink can contaminate the printing platen due to defects in the screen printing frame, and by the subsequent glass, i.e. by their lower surface, the automatic screen printing device, dryer, downstream. The ink is transferred onto the conveyor belt conveyor and the roller conveyor of the attached production apparatus. As a result, cleaning is required, and each of the dirty machine parts is manually washed using a solvent. This requires a great deal of time and large labor costs.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to automatically detect a trouble immediately when a screen printing frame is damaged or destroyed, and to prevent a large damage from occurring. It is to propose an automatic screen printing device of the type described above, in which measures can be taken.

[0007]

According to the invention, the object is to provide an evaluation circuit which is arranged in a gap between the printing plate and the screen printing frame and which can interrupt printing. Achieved by an optical monitoring device.

[0008] If a foreign object is detected in the gap monitored by the optical device, the evaluation circuit interrupts printing.

Optical monitoring devices consist, for example, of light partitions created by rows of individual photobars, each of which is provided with a light emitter and a light receiver. In this case, the distance between adjacent photoelectric barriers determines the size of the foreign matter that can be detected.

According to another embodiment, the optical monitoring device includes a suitable evaluation software for monitoring the intermediate gap between the printing platen and the lower portion of the silk printing frame in front of the defined background. It consists of a CCD camera.

[0011] Preferably, the optical monitoring device is fixed to the printing board. However, it is also possible to fix it on a mount, a silk print frame, or a unique mount of the above-mentioned device.

In the case of the screen device according to the present invention, the gap located between the printing board and the screen printing frame is formed not only during the above-described printing process but also during the lifting of the printing frame. Is monitored by an optical monitoring device so that the In particular, such monitoring is carried out when the ink drips onto the plate of the printing table due to a breach or crack in the screen mold. Screen-type screen-printed fabric or netting (tiss
Such tears in u) can be caused by continuous scraping of the scraper on the upper surface of the screen printing frame or by contact between the lower surface of the frame and the sharp edge of the glass. Of course, large-scale destruction of the frame is also detected at the level of the resulting loosened screen network.

After detecting the foreign object, the optical monitoring device sends a signal to an evaluation circuit connected to the control device of the automatic screen printing device. The evaluation device can be incorporated into the monitoring device itself, but the evaluation device and the control device only activate the monitoring device when the frame is in the raised position, and consequently the screen device during operation. Only foreign objects, not mechanical parts, are programmed so that the printing operation can be immediately interrupted.

[0014] Other features and advantages of the invention will become apparent from the following description of a preferred embodiment of an automatic screen printing device according to the invention, made with reference to the dependent claims and the accompanying drawings.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An automatic (silk) screen printing apparatus suitable for printing a glass 7 mainly comprises a printing table constituted by a mounting table 1 and a printing board 2 and a stencil screen 3 ". Screen frame 3 'and scraper 4
And a printing element arranged on the printing board. The screen frame 3 'and the stencil screen 3 "form a screen printing frame 3 which is removably fastened into a holding frame 12. The driving and guiding means of the scraper 4 are not shown here, The holding frame 12 has a screen printing frame 3 mounted therein and is connected to the printing board 2 via cylinder and piston type jacks 6 and their piston rods 6 '.

A fixed component 8 is provided on the printing plate 2 and a row of light emitters arranged above and below the fixed component, preferably over the entire length of the automatic screen printing apparatus, one behind the other. (Emetteurs) 9 is fixed. On the opposite side, a row of receptors 10 combined with the light emitters is fixed. The light emitter 9 sends light beams 11, which pass through a gap A located between the printing board 2 and the lower part of the screen printing frame 3,
Received by the light receiver 10. Therefore, the luminous flux 1
1 is a substantially closed light divider or shield (ride)
au lumineux). The distance between the light beams 11 is about 5 to 8 mm in order to reliably detect any foreign matter.
Was found to be appropriate.

The printing cycle of a screen printing device with a light monitoring device proceeds as follows.

First, the glass 7 is placed on the printing board 2. Next, the printing frame 3 of the screen is lowered by the hydraulic jack 6 and the piston rod 6 ′ so that the distance between the glass 7 and the stencil screen 3 ″ is several millimeters. At the applied pressure and at a defined speed, the stencil screen 3 "moves over the stencil screen 3" so that the stencil screen 3 "expands and contacts the glass 7 where the scraper 4 is located, and the screen ink 5 , Transferred onto the glass 7 through the opening of the stencil screen 3 ". When the scraper 4 reaches its final position, the hydraulic jack 6 lifts the screen printing frame 3 back to its original position. As soon as the screen mold 3 comes out of the gap A, the optical monitoring device is activated, so that foreign substances present in the intermediate gap A are detected. During this time, the scraper 4 returns to its original position and distributes or supplies the screen ink 5 onto the stencil screen 3 ", while the printed glass 7 is removed.
Then, the next glass 7 is positioned and the next printing cycle is started.

The monitoring device is operated by a circuit d'evaluation integrated in the light receiver 10, which circuit is connected to the control device of the automatic screen printing device and has a screen printing frame 3 and a printing device. Monitoring of the intermediate gap A between the base plate 2 is started at the moment when the lower boundary surface of the screen frame 3 is lifted after printing and passes through the light beam 11, and the boundary surface of the stencil screen 3 "is lowered before printing. It ends at the moment when it is again placed in the light beam 11. During this limited time, whether it is the loose network of the damaged stencil screen 3 "or the dripping screen ink 5, these will cause one of the light beams 11 One of them is interrupted and a signal is transmitted to the control of the automatic screen printing device so that the printing cycle is immediately interrupted automatically.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an automatic screen printing apparatus having features of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mounting stand 2 Printing board 3 Screen printing frame 4 Movable scraper 6 Hydraulic jack 7 Glass 9 Light emitting device 10 Light receiving device 11 Light flux A Gap

Claims (6)

[Claims] 1. A mounting board (1) on which a printing board (2) on which a screen printing frame (3) provided with a vertical moving means (6) is mounted is placed on a mounting table (1), and the screen is passed through a lower portion of the printing frame. An automatic screen printing apparatus for glass printing comprising a movable scraper (4) capable of extruding ink, wherein an optical gap is provided between said printing board (2) and a lower portion of said printing frame. A device, characterized in that a monitoring device (9, 10) is arranged, said optical monitoring device being connected to an evaluation circuit capable of interrupting printing. 2. An optical monitoring device comprising a plurality of photoelectric barriers (9, 11, 1) spaced from each other by a few millimeters.
Device according to claim 1, characterized in that it is a light partition created by 0). 3. The device according to claim 1, wherein the optical monitoring device comprises a CCD camera and suitable evaluation software. 4. The device according to claim 1, wherein the optical monitoring device is fixed to the printing platform. 5. The device according to claim 1, wherein the optical monitoring device is fixed to the mounting. 6. The device according to claim 1, wherein the optical monitoring device is fixed to the printing frame.