JPS6127189B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a squeegee head structure for a screen printing machine that prints thermoplastic ink called hot melt, paste, adhesive, etc. using a screen printing method.

Conventionally, screen printing using thermoplastic inks, pastes, adhesives, etc. called hotmelt has been performed by installing a heating electric resistor in an integrated structure on the plate itself, heating the plate, and softening and melting the hotmelt to a viscosity that allows screen printing. Was. In this method, as shown in FIG. 1, a hot melt reservoir 6 which has been softened and melted on a mesh type plate 3 having a heat generating electric resistor 4 integrated therein is moved over the plate 3 in the right direction using a resin or rubber squeegee 1. It was desired to print on the substrate 5 fed under the plate 3. After printing, the squeegee 1 was raised, and the ink returner 2 was lowered onto the plate 3 and moved to the left, returning the hot melt reservoir 6 to the starting position.

Printing hot melt with such a squeegee head screen printing machine had the following drawbacks. Since squeegee 1 is not heated, the heat of plate 3 and hot melt reservoir 6 is taken away by squeegee 1, and plate 3
The temperature change in the hot melt reservoir 6 was significant, and the viscosity of the hot melt became non-uniform over the entire plate 3, resulting in noticeable non-uniformity of the printed coating film. The same applies to the ink return plate 2, and the viscosity of the hot melt becomes non-uniform over the entire plate 3, causing non-uniform print coating. As mentioned above, there was a drawback that the printed coating film of hot melt was non-uniform. Furthermore, in the region of high viscosity near the lower limit of printable temperature, printing unevenness may occur or printing may not be possible, and for this reason, in consideration of temperature changes and uneven temperature distribution, plate It was necessary to set the temperature higher. In this case, since the hot melt is a thermoplastic resin, it has the disadvantage that the adhesive strength and bonding strength of the hot melt on the plate deteriorate rapidly due to thermal history. The conventional methods had the above-mentioned drawbacks.

The present invention eliminates such drawbacks, and its object is to provide a squeegee head structure for a screen printing machine that can provide a uniform and stable printed coating in hot melt screen printing.

The present invention will be described in detail below based on Examples. In FIG. 2, a metal squeegee 11 in which a heating element 12 having a temperature control device 10 is embedded, and a plate spring 13 having one end fastened to the upper part of the metal squeegee 11 are fixedly held at the other end by a squeegee holder 14. The lower end of the vertical guide shaft 15 slidingly guided by the rocking body 16 is fixed to the squeegee holder 14, and a vertical drive cylinder 20 provided parallel to the vertical guide shaft 15 is fixed to the rocking body 16. The door 20a is fixed to the squeegee holder 14.
A swing center shaft 19 is provided coaxially with the metal squeegee 11 and the leaf spring 13. A pair of swingable perforations 18 provided oppositely to the frame of the squeegee head (not shown in the figure) swing between the swingable perforations 17. A swing drive cylinder rod 21a of a swing drive cylinder 21 provided at a position eccentric to the swing center axis 19
is connected to the rocking body 16 via a connecting shaft 22 provided at the force point of the rocking body 16. Swing drive cylinder 21
is connected to a squeegee head frame (not shown) by a cylinder connecting shaft 23.

In the above structure, the metal squeegee 11 can be controlled to any temperature by the temperature control device 10 and the embedded heating element 12, and can be maintained at the same temperature as the temperature suitable for softening and melting the hot melt. . Therefore, the hot melt reservoir 6 in a softened and molten state
By keeping the plate 3 and the metal squeegee 11, which receive heat from the heating electric resistor 4, at the same temperature, the transfer of heat between them can be extremely reduced, and the temperature difference between the hot melt reservoir 6 and the plate 3 caused by the squeegee 1 can be reduced. Since temperature changes can be eliminated, the uniformity and stability of printed coatings can be improved. Further, as shown in FIG. 3, the entire squeegee head is moved to the right, and the hot melt pool 6 that has softened and melted on the plate 3 is moved to the right by the metal squeegee 11 and applied to the printing material 5 supplied under the plate 3. Print. After printing, move the metal squeegee 11 together with the squeegee holder 14 to the rocking body 16.
It is moved upward by a vertical drive cylinder 20 and its vertical drive cylinder rod 20a. Next, the oscillating body 16 is moved around the oscillating central axis 1 by the oscillating cylinder 21 and its oscillating drive cylinder rod 21a.
Swing counterclockwise around point 9. After that, the metal squeegee 11 is moved by the vertical drive cylinder 20 and its vertical drive cylinder rod 20a.
is lowered to the right print end position 24. After descending, the entire squeegee head is moved to the left to move the hot melt reservoir 6 to the left starting point 25. After the shift, the metal squeegee 11 is moved to the left printing start position 26 by the operation of the vertical drive cylinder 20 and the swing cylinder 21. According to this mechanism, there is no need to use an ink returner. As mentioned above, this can eliminate the temperature difference and temperature change between the hot melt reservoir 6 and the plate 3 caused by the ink return 2, so it is possible to improve the uniformity and stability of the printed coating film and at the same time keep the hot melt temperature constant. There is no need to raise the set temperature, and deterioration of the adhesive strength and bonding strength of hot melt can be suppressed. What is important here is that the squeegee material used in conventional screen printing is resin-based or rubber-based with a rubber hardness of 60 to 80 HV, which has a higher elasticity than the metal squeegee of the present invention. It has a very small modulus and has the elasticity to make a good line contact with the plate and printing substrate.
This is an essential condition in order to obtain a uniform thickness of the entire printed coating. Furthermore, uniformity of the printing pressure across the squeegee is essential in order to obtain a printed coating film without bleeding. However, when using a metal squeegee, it is necessary to attach the end of the metal squeegee parallel to the plate and the printing material. If this is not done, the thickness of the printed coating will be uneven and smearing will occur, resulting in damage to the printed coating. The quality will be poor. The second method to solve this problem is
As shown in the figure and FIG. 3, a plate spring 13 is provided on the top of the metal squeegee 11, and the whole is rotated by a swinging mechanism to rotate the plate 3 and the printing substrate 5 by 10 to 20 degrees to the left and right from the perpendicular position. It is tilted to some degree. With the metal squeegee 11 and the leaf spring 13 tilted to either the left or right, applying printing pressure by the vertical guide mechanism causes the leaf spring 13 to bend, causing the metal squeegee 1 to bend.
The entire end surface of the printing plate 1 is in close contact with the plate 3 and the printing material 5, so that printing pressure can be made uniform.

Therefore, by providing the leaf spring 13, the elastic disadvantage caused by using a metal material instead of a resin or rubber material as the squeegee material was solved.

As in the above example, a metal squeegee with a heating element embedded therein connected to a temperature control device, a leaf spring supporting this, and a swinging mechanism tilt the metal squeegee to apply uniform printing pressure to the printed material. Due to the close contact, a hot melt printed coating film can be obtained uniformly and stably, and a metal squeegee can be used. Further, there is no need to set a high temperature for the hot melt, and deterioration of the adhesive force and bonding force of the hot melt can be suppressed. In this way, it is possible to provide a squeegee head structure for a screen printing machine that can uniformly and stably obtain a hot melt printed coating.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the main parts of a conventional screen printing machine. FIG. 2 is a sectional view of a main part of a squeegee head of a screen printing machine according to an embodiment of the present invention. FIG. 3 is a diagram showing the positional relationship between the squeegee head and printing of the screen printing machine of the present invention. 1... Squeegee, 2... Ink return, 3... Plate, 4...
Heat generating electrical resistor, 5... Printing material, 6... Hot melt reservoir, 10... Temperature control device, 11... Metal squeegee, 12... Heat generating element, 13... Leaf spring, 14... Squeegee holder, 15... Vertical guide shaft, 16... Rocking moving body,
17...per swing degree, 18...per swing degree, 19...
Swing center axis, 20...Vertical drive cylinder, 20a
... Vertical drive cylinder rod, 21... Rocking drive cylinder, 21a... Rocking drive cylinder rod,
22...Cylinder connection shaft, 24...Right print end position, 25...Left start point, 26...Left print start position.

Claims (1)

[Claims] 1 Thermoplastic ink by screen printing method,
A squeegee head structure of a screen printing machine that prints paste, adhesive, etc. includes a metal squeegee in which a heating element connected to a temperature control device is embedded, a plate spring whose lower end is fixed to the metal squeegee, and a plate spring of the plate spring. A vertical guide shaft whose upper end is fixed to the lower end and whose lower end is fixed to the upper end of the longitudinal extension of the leaf spring, and a cylinder rod of a vertical drive cylinder arranged and fixed to the side of the vertical guide shaft are attached. a squeegee holder, a swinging body that locks the vertical drive cylinder and holds the upper end of the vertical guide shaft in a vertically movable manner; A swingable perpendicular unit that swings between a pair of swingable permutations that are provided on the side of a swing center axis provided in a right angle direction and arranged on a separately provided squeegee head frame, and a swinging body. A swing drive cylinder rod of a swing drive cylinder that swings about the swing center axis and is connected to the squeegee head frame by a cylinder connecting shaft is fixed at a side position of the vertical drive cylinder. , maintaining the metal squeegee at a constant temperature by a heating element connected to the temperature control device;
A squeegee head structure for a screen printing machine, characterized in that the metal squeegee slides at an angle with respect to the printing material.