WO1993004862A1

WO1993004862A1 - Pad printing machine

Info

Publication number: WO1993004862A1
Application number: PCT/EP1992/001730
Authority: WO
Inventors: Wilfried Philipp
Original assignee: Tampoprint Gmbh
Priority date: 1991-09-09
Filing date: 1992-07-30
Publication date: 1993-03-18
Also published as: DE4129946A1; DE4129946C2

Abstract

A pad printing machine (1) is provided with a block support (3) to take a block (4), with an ink feed device (13) having a hollow body (12), the front surface (14) of the hollow body (12) bearing on the block (4) when the machine (1) is in operation, with a device for pressing the front surface (14) of the hollow body (12) against the block (4), with a device for producing a relative movement between the block (4) and the hollow body (12) and with a pad (9) which can be pressed on the inked block (4) and removes the ink from the recesses in the block (4) in order to transfer it to an object to be printed. In this machine, the hollow body (12) has projecting sections, and any leakage of the ink in the hollow body (12) is reliably prevented in that the device for pressing the front surface (14) of the hollow body (12) against the block (4) has a magnet, that the magnet is arranged directly or indirectly on the block support (3) and that the projecting sections of the hollow body (12) are immediately adjacent to the magnet, especially the pole shoes, and are affected by the magnetic force of the magnet.

Description

Pad printing machine

The invention relates to a tampon printing machine with a plate holder for receiving a plate, with a ink supply device having a hollow body, the hollow body resting on the plate with its end face when the machine is working and with a device for pressing the end face of the hollow body against the plate, with a device for generating a relative movement between the cliché and the hollow body and with a tampon which can be pressed onto the inked cliché and which absorbs the color from the recesses of the cliché in order to be transferred to an object to be printed on, a magnet for permanently pressing on the entire face of the hollow body is provided against the cliché.

Pad printing machines are known from EP 0 140 165 A and DE 37 37 931 A, in which the cliché which bears the engravings is colored by means of the hollow body. The hollow body contains the required printing ink for this purpose and lies with its open end with its front edge on the plate, so that the surface of the plate covered by the hollow body is wetted with the printing ink. The device for generating a relative movement between the cliché and the hollow body is used to move the hollow body over the engraving, which receives the printing ink in its depressions. When the hollow body returns, the excess ink is scraped off, and the printing ink remains in the depressions, which is then picked up by the tampon and transferred to the object to be printed. In order to achieve a clean printing process, the hollow body must be pressed onto the surface of the plate with a certain force. There are a number of mechanical ones for this Known designs that load the hollow body, for example by means of springs. It has been shown that the point of application of the force pressing the hollow body onto the cliché surface should, if possible, be in the region of the end face of the hollow body resting on the cliché surface, since otherwise the hollow body has an excessive tendency to tip over. Because of this tendency to tilt, which is supported in particular by the reciprocating movement of the hollow body on the cliché, the contact pressure is reduced in certain areas of the end face, so that the risk of ink leakage is increased. If the cliché also has unevenness, it is almost impossible to avoid the ink running out of the hollow body. Particularly when the machine is at a standstill, this can lead to contamination of large areas of the machine and considerable loss of color.

In the subject of DE 37 37 937 A an attempt is made to mechanically press the hollow body onto the cliché via a gimbaled ring. However, this is only possible if the hollow body is at rest and the cliché is moved under the hollow body relative to it.

With DE 88 09 564 U and DE 90 06 932 U a device is known in which the hollow body is provided with a magnet. This magnet is located inside the hollow body and is located near the surface of the cliché. In this way, an attempt is made to bring about the contact pressure of the hollow body by the magnet in order to thereby get rid of mechanical devices which press the hollow body by means of spring force. However, it has been shown that hollow bodies of this type have a significantly greater tendency to tilt, since the anchoring point of the magnet on the hollow body lies in an area lying away from the cliché. In addition, due to the magnetic field surrounding it, the magnet located inside the hollow body, which is constantly flushed with the color, acts separation of the printing ink, which leads to unclean or unusable prints. In addition, the contact pressure generated by the magnet is usually too low to press the hollow body onto the cliché with the required force. Furthermore, the weight of the hollow body is increased by the additional magnet, so that on the one hand a further increase in the tendency to tip occurs, on the other hand, correspondingly large drive elements are required to accelerate and brake the hollow body. Finally, the chamber volume is reduced by the magnet located inside the hollow body.

DE 85 00 081 U discloses a holding device for a film cliché, in which a large number of magnets are arranged in the cliché holder. A ferromagnetic cliché film is held on these magnets.

DE 34 16 029 C2 has made known a squeegee device for screen printing which, in addition to the squeegee, has a magnetizable mass which is attracted and moved via a magnet mounted under the material to be printed. However, the contact pressure of the magnet is only so high that the ink is passed through the screen by the squeegee. A clean doctoring of the surface of the screen is not necessary and also not possible with such a device.

Proceeding from DE 88 09564 U, the invention is based on the object of designing the pad printing machines mentioned at the outset in such a way that the hollow body is pressed securely onto the cliché, so that leakage of the ink from the hollow body is avoided with certainty. Furthermore, the device for pressing the hollow body onto the cliché should not hinder the mobility of the hollow body. After all, the Pad printing machine can also be suitable for high printing cycles with high-speed hollow cylinders and deliver clean prints.

Starting from a state of the art according to DE 88 09 564 U, this object is achieved according to the invention in that the hollow body is provided with surface sections lying immediately above the cliché, that the magnet is fixed directly or indirectly on the cliché support and that the surface sections of the hollow body in immediate proximity to the magnet, especially to the pole pieces, are arranged and pushed towards the cliché.

The configuration of the pressing device according to the invention has the advantage that the freedom of movement of the hollow body is not restricted by means mechanically connected to it, for example springs, lever arms or the like. The device for generating a relative movement between the cliché and the hollow body can be moved on the cliché as desired. In addition, the configuration according to the invention has the advantage that the hollow body according to the invention, in contrast to the known hollow body having an internal magnet, has a low weight. Because of this, the machine according to the invention can be operated at higher speeds, since smaller masses have to be accelerated and braked with the hollow body.

Another advantage is that there is no separation of the color because the magnet is outside the hollow body. pers is arranged. This significantly reduces the risk of misprints.

In another embodiment, the hollow body is at rest and the cliché is moved relative to the hollow body. The magnet can be connected directly to the cliché carrier, so that this too is moved. However, the magnet can also be indirectly connected to the plate holder in such a way that it is at rest and the plate is moved relative to the hollow body and the magnet. This also has the advantage of reducing the moving masses.

The force pressing the hollow body onto the cliché is generated by the magnet, which is in the immediate vicinity of the sections which project laterally from the hollow body. These sections can be arranged so that they are in the cliché plane, so that the risk of the hollow body tipping is reduced to a minimum.

In another embodiment, the magnet is located above these cantilevered sections and is arranged such that it exerts a repulsive force on them, the sections themselves being magnetic.

These sections are advantageously provided on the edge of the end face of the hollow body. They can be designed as opposite arms. Another embodiment provides that the section is designed as a ring surrounding the hollow body, which is preferably fixed to the hollow body by radial pins in the end region. The ring is preferably removable and interchangeable. The ring forms a rotational symmetrical body with respect to the longitudinal axis of the hollow body, so that the magnetic force acting on the ring is distributed uniformly over the radial pins over the circumference of the hollow body.

In a particularly preferred embodiment, the magnet is arranged below the cliché. In this embodiment, the projecting sections can be designed individually, so that an optimal holding force is generated.

Another embodiment provides that the magnet is arranged outside the cliché area. This has the advantage that the color is not influenced by the magnetic force, and in particular there is no separation of the color.

The magnet is preferably arranged to the side of the cliché. This has the advantage that the poles of the magnet can be flush with the plane of the cliché surface, so that an optimal introduction of forces takes place in the region of the end face on the hollow body. This counteracts tilting of the hollow body with great certainty.

A further development provides that the height of the magnet can be adjusted and the air gap between the magnet and the section on which the magnetic force acts can be adjusted. In this way, the contact pressure of the hollow body on the cliché can be set to predetermined values, so that, for example, the most favorable contact pressure can be set for different hollow bodies or hollow bodies with different fill quantities of printing ink. In simple embodiments, the magnet is a permanent magnet. Another possibility of adjusting the magnetic force is achieved in that the magnet is an electromagnet, the magnetic force of which can be controlled via the supply of electrical energy. Either the voltage or the current strength can be varied.

As already mentioned above, either the hollow body can be movably guided in the longitudinal direction of the plate or, in kinematic reversal, the plate carrier can be movably guided in the longitudinal direction of the plate relative to the hollow body.

Further features, advantages and details of the invention result from the following description, in which particularly preferred exemplary embodiments are described in detail with reference to the drawing. The features shown and mentioned in the description can each be implemented individually or in any combination with one another in the invention. The drawing shows:

Figure 1 is a schematic side view of a pad printing machine;

FIG. 2 shows a perspective view of an ink supply device designed as a hollow body;

FIG. 3 shows a side view of the hollow body seated on the cliché, partially broken;

Figure 4 shows a section IV-IV of FIG. 3; Figure 5 is a side view in the direction of arrow V of FIG. 4;

Figure 6 is a side view corresponding to FIG. 5 of another embodiment.

The pad printing machine shown in FIG. 1, which is denoted overall by 1, has a machine frame formed essentially by two side plates, one of which is shown as a side plate 2, in which a plate holder 3 on which a plate is placed 4 is releasably attached, is slidably mounted in the horizontal direction according to arrow 5. A device, not shown, for displacing the plate holder 3 in the direction of the arrow 5 moves the plate holder 3 from its one end position, shown in FIG. 1 with a solid line, into its other end position 6, shown in FIG. 1 with a broken line, and back again.

Furthermore, the tampon printing machine 1 is provided with a receiving device 7 for a shaft 8 of a tampon 9. This tampon 9 is guided vertically displaceably in the direction of the double arrow 10 by means of a device (not shown), so that it can be brought from its one end position, which is shown with a solid line, into its other end position 11, which is shown with a dash-dotted line . From Fig. 1 it can be seen that the plate holder 3 with the fixed plate 4 and the tampon 9 penetrate in the extended positions shown with dash-dotted lines. This is necessary in order to pick up the ink from the engraving of the cliché 4 with the tampon 9 and towards an object to be printed transfer. This process is described in more detail below.

Finally, an ink supply device 13 having a hollow body 12 can be seen in FIG. 1, which rests with its lower end face 14 on the surface of the plate 4. The hollow body 12 contains the printing ink required for the printing process, with which the cliché 4 is colored.

A print process is briefly explained below:

If the plate holder 3 with the plate 4 attached to it is in its right-hand end position shown in FIG. 1, the engraving to be inked and having the printed image lies under the hollow body 12 and is wetted with the printing ink located in the hollow body 12. If the cliché holder 3 moves with the cliché 4 into the end position 6 shown on the left, the end face 14 lifts off the excess printing ink from the engraving and the cliché 4 and only the printing ink remains in the recesses of the engraving. When the plate holder 3 has reached its left end position, the tampon 9 moves from its upper to its lower end position 11 and is pressed onto the plate 4. The tampon 9 picks up the printing ink from the engraving. Then first the tampon 9 moves into its upper end position and then the plate holder 3 returns to its right end position. The tampon 9 then again moves in the vertical direction downwards until it hits an object to be printed which is arranged below the plane of the plate carrier 3. There he transfers the printing ink on the surface of the tampon 9 to this object and leaves the desired printed image there. Then it moves back to its upper end position and the pressure cycle is ended. The motion sequences can also flow smoothly into one another.

In order to achieve a clean stripping or scraping off of the excess printing ink from the plate 4 after the engraving has been colored, the hollow body 12 is pressed onto the plate 4 with a suitable device. It is important to ensure that tilting of the hollow body 12 on the cliché 4 is prevented with certainty in order to prevent the color in the hollow body 12 from leaking. In addition, pressing the hollow body 12 onto the plate 4 causes the hollow body 12 to follow slight unevenness in the plate 4, which improves the print quality.

FIG. 2 shows a perspective representation of an embodiment of the hollow body 12, which is open at its lower end 15 and there has the end face 14 made of hard material. This end face 14 has the effect of a squeegee wiping off the excess ink from the printing block 4. In the area of this end face 14, the hollow body 12 is provided with a ring 16 surrounding it, which forms a projecting section 17. The vertical distance between the end face 14 and the underside of the ring 16 is exaggerated in FIG. 2 and in the following figures and is not shown to scale. This distance is between a few μm to 0.5 mm. Finally, it can be seen from FIG. 2 that the hollow body 12 is closed with a cover 18. This lid 18 prevents the solvent of the printing ink from evaporating and allows easy access to the interior of the hollow body 12, for example for refilling printing ink or for emptying the hollow body 12. FIG. 3 shows a section III-III according to FIG. 4, the hollow body 12 being partially broken open. 3 that the hollow body 12 rests on the cliché 4 with its black end face 14, whereas there is also a distance (not shown to scale) between the surface of the cliché 4 and the underside of the ring 16. Furthermore, a magnet 19 can be seen which extends below and to the side of the cliché carrier 3, as can be seen more clearly from FIG. 5.

In the exemplary embodiment shown in FIG. 3, the ring 16 is designed as a separate component and can be removed from the hollow body 12. This ring 16 has several, in particular three, radial pins 20 distributed around the circumference, which extend radially inward from the ring 16. These pins 20 rest with their radially inner ends in recesses 21 which are provided on the circumference of the hollow body 12. For this purpose, the hollow body 12 has a further ring 22 in the region of its end face 14, into which cutouts forming the recess 21 are incorporated. Due to the uniform distribution of the recesses 21 and the arrangement of the pins 20 on the ring 16, a uniform introduction of force from the ring 16 into the further ring 22 and thus into the hollow body 12 is achieved. In addition, the interchangeable fixing of the ring 16 on the hollow body 12 creates the possibility of exchanging this ring 16 for a larger or smaller sized ring, for example.

From Fig. 4 it can be seen that the ring 16 overlaps the plate carrier 3 laterally and over the poles 23 and 24 of the magnet 19 comes to rest. The distance between the poles and the underside of the ring 16 has a certain dimension, by means of which the magnetic attraction force can be set.

To set this magnetic force, the magnet 19 can be adjusted in height in the direction of the double arrows 25, so that the air gap between the poles 23 and 24 and the ring 16 can be varied. In one embodiment, the magnet 19 is connected to the plate holder 3 and therefore follows its horizontal movements. In other exemplary embodiments, the magnet 19 is connected to the frame of the pad printing machine 1 and the plate holder 3 moves relative to the hollow body 12 and the magnet 19. This has the advantage that smaller magnets 19 can be used and that the orientation of the magnet 19 is easier to carry out with respect to the hollow body 12.

In the embodiment shown in FIG. 6, the plate carrier 3 forms the magnet 19, so that the ring 16 is acted upon by the magnetic force over its entire circumference. This has the advantage that the ring 16 can be made smaller in its circumference or that the magnet 19 can be made weaker in terms of its magnetic force. The distance between the underside of the ring 16 and the surface of the magnet 19 can be set in this embodiment by differently dimensioned rings 16, which are attached to the hollow body 12 as desired. It is attached in the manner of a bayonet lock, the pins being inserted from below through the openings 26 and the ring being rotated by 60 ° until the pins 20 come to rest in the recesses 21.

Claims

1) Tarapondruck machine (1) with a plate holder (3) for receiving a plate (4), with a hollow body (12) having ink feed device (13), the hollow body (12) at work of the machine (1) with it End face (14) on the cliché (4) rests, with a device for pressing the end face (14) of the hollow body (12) against the cliché (4), with a device for generating a relative movement between the cliché (4) and the hollow body (12), and with a tampon (9) which can be pressed onto the colored cliché (4) and which absorbs the color from the recesses of the cliché (4) in order to transfer it to an object to be printed, whereby a magnet (19 ) for permanent pressing of the entire end face (14) of the hollow body (12) against the cliché (4) is provided, characterized in that the hollow body (12) is provided with surface sections (17) lying immediately above the cliché (4) that the magnet (19th ) is fixed directly or indirectly to the plate holder (3) and that the surface sections (17) of the hollow body (12) are arranged in the immediate vicinity of the magnet (19), in particular to the pole pieces, and are pushed in the direction of the plate holder (4) .

2) Pad printing machine according to claim 1, ^' characterized in that the magnet (19) on the sections (17) exerts an attractive force.

3) pad printing machine according to claim 1, characterized in that the sections (17) are magnetic and the magnet (19) on the sections (17) exerts a repulsive force.

4) Pad printing machine according to one of the preceding claims, characterized in that the sections (17) are provided on the edge of the end face (14) of the hollow body (12)).

5) Pad printing machine according to one of the preceding claims, characterized in that the sections (17) are formed as opposite arms.

6) Pad printing machine according to one of the preceding claims, characterized in that the sections (17) are arranged rotationally symmetrically with respect to the longitudinal axis of the hollow body (12).

7) Pad printing machine according to one of the preceding claims, characterized in that the magnet (19) is arranged outside the printing block area.

8) Pad printing machine according to one of the preceding claims, characterized in that the magnet (19) is arranged laterally next to the cliché (4). IS ^"

9) Pad printing machine according to one of the preceding claims, characterized in that the magnet (19) is arranged below the cliché (4).

10) Pad printing machine according to one of the preceding claims, characterized in that the magnet (19) is adjustable in height and thereby the air gap between the magnet (19) and the section (17) on which the magnetic force acts can be adjusted.

11) Pad printing machine according to one of the preceding claims, characterized in that the magnet (19) is a permanent magnet.

12) Pad printing machine according to one of the preceding claims, characterized in that the magnet (19) is an electromagnet.

13) Pad printing machine according to one of the preceding claims, characterized in that the electro-magnet can be controlled in its magnetic force.

14) Pad printing machine according to one of the preceding claims, characterized in that the hollow body (12) is movably guided in the longitudinal direction of the plate (4).

15) pad printing machine according to any one of claims 1-13, characterized in that the plate holder (3) is movably guided in the longitudinal direction of the plate (4).