EP0086742B1 - Printing machine with printing pad and inking device - Google Patents

Abstract

The swab printing machine is provided with an inking device having a carriage. A spreader support with a spreader head is tippably arranged on the frontal side of the carriage and can reciprocate over a printing plate. The spreader which is inclined backward by about 20 DEG , takes ink from the ink container during its forward motion and distributes it over the printing plate, whereby the two rounded slide feet achieve the uniform distribution of the ink. During the return motion the excess ink is wiped off by a doctor blade. A laterally running recess is arranged in the lower portion of the spreader and the lower edge of this recess forms a narrow dipping edge. An adjustable central closure is provided on the spreader support and on the spreader head. After the initial positioning of the spreader head it is possible to remove same, clean it and remount it, without making readjustments. Because of the narrow dipping edge, the same quantity of ink is always transported onto the printing plate, regardless of the immersion depth of the spreader.

Description

The invention relates to an inking device for a tampon printing machine according to the preamble of patent claim 1.

With the pad printing process, flat and uneven surfaces of objects can be printed in the simplest way. After inking the cliché and removing the excess ink, the pressure pad, also called a tampon, is pressed onto the cliché, raised and then pressed against the object to be printed, in order to transfer the print image.

A pad printing machine of this type is known from CH patent 546 644. A spatula guide body is attached to the spatula support of this machine, which has a passage in which the spatula is slidably mounted. The spatula is provided with a slot in the middle, in which a guide pin engages, in order to thereby limit the height of the spatula between two end positions.

The spatula made of sheet steel falls due to its own weight down to the stop of the longitudinal slot on a pin. In the lower end position, the lower edge of the spatula plunges a few millimeters into the paint container. The immersion depth is dimensioned so that a certain amount of color is transported onto the cliché.

Immersing yourself too deeply has negative consequences. On the one hand, too much paint would be pushed onto the cliché and, on the other hand, paint would be sprayed backwards by the scraper knife each time the paint container was moved back and dipped.

In order to keep the optimal immersion depth reasonably constant, the paint container must be refilled frequently. There is also no mixing of the paint, since the spatula only ever penetrates the surface zone of the paint and the lower paint zones in the container remain motionless.

Another disadvantage of the known coloring device is that after cleaning the spatula and the spatula carrier, the exact position on the slide has to be adjusted and fixed, which has to be carried out very carefully and precisely and is therefore time-consuming.

The object of the invention is to create a coloring device for a tampon printing machine in which the disadvantages mentioned are avoided. Regardless of the filling of the ink container, it should be possible to always transport the same amount of ink onto the cliché. The paint should be mixed well periodically in the paint container. Furthermore, it should be possible to easily dismantle the squeegee, spatula and the spatula carrier for cleaning and reassemble without adjustment.

This object is achieved according to the invention by the features defined in the characterizing part of patent claim 1.

• Figur 1 eine Seitenansicht auf eine Tempondruckmaschine, wobei ein Stapel zu bedruckender Gegenstände perspektivisch dargestellt ist.
• Figur 2 eine Seitenansicht auf die Einfärbevorrichtung der Tampondruckmaschine gemäss Fig. 1, in grösserem Massstab.
• Figur 3 eine Draufsicht auf die Einfärbevorrichtung gemäss Fig. 2.
• Figur 4 eine Draufsicht auf den Spachtel.
• Figur 5 einen Querschnitt durch den Spachtel,
• Figur 6 den Spachtelträger in auseinandergezogener Darstelltung, teilweise im Schnitt, und
• Figur 7 Stirnansichten auf den Spachtelträger bzw. den Spachtelkopf nach dem Pfeil VII gemäss Fig. 6.

An exemplary embodiment of the invention is explained in more detail below with reference to the drawings. Show it :

• Figure 1 is a side view of a tempo printing machine, wherein a stack of objects to be printed is shown in perspective.
• Figure 2 is a side view of the inking device of the pad printing machine according to FIG. 1, on a larger scale.
• FIG. 3 shows a top view of the coloring device according to FIG. 2.
• Figure 4 is a plan view of the spatula.
• FIG. 5 shows a cross section through the spatula,
• 6 shows the spatula carrier in an exploded view, partly in section, and
• FIG. 7 end views of the spatula carrier or the spatula head according to arrow VII according to FIG. 6.

The pad printing machine shown in FIG. 1 has a machine base 1. which is provided on the front with a table for the ink fountain and cliché holder 2. A machine part 3 is arranged above this holder 2, to which the printing device 4 is fastened with the tampon 5. The latter consists, for example, of silicone rubber or another elastic material.

The coloring device comprises a color donor carriage 7, on which a spatula carrier 8 is fastened in a tiltable manner. The cliché plate 9 is mounted on the holder 2. The documents to be transferred are photographically applied to the plate and etched. After the coloring, the etched areas of the plate are filled with paint. The tampon 5 is now lowered pneumatically onto the plate. then raised again after a predetermined stroke and moved forward or pivoted. Then it is pressed onto the object G to be printed.

The spatula support 8 is fastened to two lateral arms 10 of the slide 7 which is guided to move back and forth. A spatula head 11, on which both the spatula 12 and a doctor blade 13 are arranged, is mounted on the spatula carrier 8 by means of a knurled screw 14. The latter is mounted such that it can be tilted about the axis 15. the tilting movement being effected by a rod 16 which can be moved back and forth relative to the slide 7. The rod is articulated to the upper part of the spatula support 8 and is driven by control means, not shown.

The spatula 12 is inclined slightly backwards from the vertical (for example approx. 20 °). It is rectangular in shape and has a vertical slot 17, in which a pin 18 of the spatula head 11 loosely engages. This achieves the lateral guidance of the spatula 12 on the cliché.

The spatula also has a transverse recess 19, which is arranged below the vertical slot 17. The recess 19 is laterally delimited by the two narrow vertical wall parts 20 and at the bottom by the narrow immersion edge 21, and has a rounded sliding block 22 on each side.

As can be seen from FIG. 2, the stroke limitation of the spatula 12 is selected such that the immersion edge 21 touches the bottom 24 of the paint container 23. The paint container 23 has an inclined surface 25. which rises from the floor 24 towards the cliché.

When the carriage 7 moves forward, the spatula carrier 8 is tilted upward, so that the doctor blade 13 does not touch the cliché. The spatula 12 slides along the inclined surface 25 of the ink container 23 and pushes a layer of ink onto the cliché plate 9. As a result of the recess 19 and the narrow immersion edge 21, the same amount of ink is always removed from the container regardless of the immersion depth. Since the immersion edge 21 penetrates to the bottom of the container 23, the paint is mixed well with each immersion.

After the plate 9 has been coated with paint, the spatula support 8 is tilted downward, so that the flexible doctor blade 13, which is also inclined to the rear, touches the plate 9. During the backward movement of the carriage 7, the excess ink is stripped back by the cutting edge of the knife 13 from the printing plate 9 into the ink container.

During the backward movement, the spatula slides in the container 22 on the paint surface without immediately dipping into the paint. This behavior is explained by the low weight. as well as a flattening of approximately 15 ° on the immersion edge 21, which generates the buoyancy during the backward movement. As a result, the spatula only sinks through the paint to the bottom of the container 24 when the end position is at a standstill.

In order to be able to easily dismantle the spatula support 8 with the spatula head 11 and the spatula 12 for cleaning and then reassemble it without any adjustment work, the following constructional structure, which acts as a central lock, has been selected: the pin 18 provided with a hole for the screw 14 is also included Press fit in the spatula head 11. Its protruding part consists of an inner section 26 with a round cross-section and an enlarged outer section 27 with two parallel, side surfaces 28, the spacing of which corresponds to the diameter of the round section 26, so that the spatula can be easily pushed on. The parallel surfaces 28 are perpendicular to the lower edge of the spatula head 11.

In the spatula carrier 8 there is an insert 29 with a threaded bore 30 for the screw 14. The part of the insert 29 facing the spatula head 11 is provided with an extension 31 in which a recess 32 is arranged, likewise with two parallel side surfaces 33.

An adjusting screw 34 is provided on each side of the spatula support and acts on a stop 35 arranged eccentrically to the axis of the insert 29. The insert can be rotated and fixed in the spatula support by means of the screws 34.

When the spatula head 11 is inserted into the spatula carrier 8, the pin portion 27 penetrates into the recess 32, the mutual position being given by the parallel surfaces. Now the position of the spatula head is precisely adjusted by means of the screws 34, so that the knife edge 13 is aligned exactly parallel to the surface of the cliché.

The spatula 12 itself does not have to be aligned since it is held loosely by the inner pin section 26 and adapts itself to the surface of the cliché. With each further disassembly and assembly of the spatula head, a new alignment is no longer necessary, since the two parallel surfaces of the pin section 27 and the recess 32 ensure precise positioning.

An articulated bearing 36 for the end of the rod 16 is arranged above the insert 29.

In the case of wide spatulas, there may be several transverse slots 19 arranged next to one another in order to ensure the stability of the spatula. With such a spatula, it is also possible to carry out multi-color printing, in which case a number of ink containers corresponding to the number of transverse slots must be provided.

Claims (6)

1. An inking mechanism for a pad printing press comprising a carriage on whose end face a spreader carrier (8) reciprocable by way of a block plate (9) is tiltingly mounted, the carrier (8) having a spreader head (11) in which a spreader (12) disposed freely in a guide slot acts downwardly by its own weight and in the advancing movement takes ink from an ink reservoir (23) and distributes the ink over the block, a doctor blade (13) which is disposed in the spreader head (11) removing surplus ink in the return movement, characterised in that the bottom part of the spreader (12) is formed with at least one recess (19) which extends transversely to the direction of advance during application of the ink and whose bottom edge (21) is operative as a narrow dip surface between the applying edge and the recess (19) : the spreader carrier (8) is formed with a recess (32) for an insert (28) of the spreader head (11) to locate the same ; and the insert (28) is adapted to receive a spin (18) which is anchored to the spreader head (11) and which has a projecting part (27) while the recess (32) has a screwthreaded part (30) which is in axial extension of the recess (32) and which is adapted to receive a screw (14), the same extending axially through the whole length of the pin (18).

2. A mechanism according to claim 1, characterised in that above the transverse recess (19) there is a vertical slot (17) for vertical guidance of the spreader (12), the slot (17) being engaged by the pin (18), the vertical movement being such that the edge (21) touches the base (24) of the ink reservoir (23) ; and the same has an inclined surface (25) which rises from the base (24) towards the block (9) and along which the dip edge (21) slides up during the advance of the carriage (7).

3. A mechanism according to claim 1, characterised in that the pin part (27) is adapted to the recess (32) and such part and such recess have identical locating surfaces (28, 33) opposite one another.

4. A mechanism according to claim 3. characterised in that the pin part (27) has two parallel locating surfaces (28) which are perpendicular to the edge of the doctor blade (13), and the recess (33) has two corresponding parallel surfaces (33).

5. A mechanism according to claim 1, characterised in that an insert (29) for the screwthreaded part (30) is rotatably mounted in the spreader carrier (8) and two lateral adjusting screws (34) operative on the insert (29) are provided to rotate the same and locate it in the required position.

6. A mechanism according to claim 1, characterised in that the spreader (12) is made of light metal and hard anodized.

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