EP0474262A1 - Pad printing machine - Google Patents

Abstract

A pad printing machine has a fastener for a block (70) and an ink supply device with a hollow body. When the machine is operating, the hollow body lies with its end face on the block. In the region of its end face, the hollow body (1') is constructed in such a way that it can bend or twist in this region and the said region is joined to the rest of the hollow body by a connection allowing relative movement between the region of the end face and the rest of the hollow body. As a result, the end face adapts itself to the surface of the block. <IMAGE>

Description

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

Such a machine is known from EP-A-0 140 165. The ink container, together with the part having the end face, forms a largely rigid structure, the end face of which cannot follow the deviations of the surface of the plate from an exact plane. The known machine requires that the surface of the plate be largely flat, with deviations from the plane in the range of approximately a maximum of 10 μm being permissible if an excellent printing result is to be achieved. Therefore, steel plates are preferably used in the known machine.

The tampon can be moved vertically from an upper end position into a lower end position and back via a guide piece, wherein it is pressed onto the cliché in the lower end position. At the same time, the cliché is moved back and forth in a horizontal direction by means of a piston-cylinder unit, where it is colored in one end position and the color is lifted off the cliché by means of the tampon in the other end position. It has been shown that only a certain number of prints per unit of time are possible with such a pad printing machine.

The invention has for its object to provide a machine of the type described above, with the higher pressure frequencies are possible.

This object is achieved in that the drive device for the relative movement between the hollow body and the cliché has a rotationally drivable curve, that a pivotally mounted lever has two support rollers which are in engagement with the curve, such that the lever through the curve in is pivotable in both pivoting directions, and that the part to be moved is coupled to the lever.

One advantage is that a simple drive (in the exemplary embodiment a drive of the cliché) is possible.

The object is also advantageously achieved in that a drive device for the tampon has a rotationally drivable curve, that a pivotably mounted lever has two support rollers which are in engagement with the curve, such that the lever can be pivoted through the curve in both pivoting directions , and that the tampon is coupled to the lever. An advantage is that this enables simple actuation of the tampon.

The machine with a mechanical drive of the tampon and for the relative movement between the cliché and the ink container has the advantage over machines with a pneumatic drive that, because all movements are positively controlled, a particularly fast running of the machine is possible, in particular also because It is not necessary to determine whether certain machine parts have reached their desired position by special sensors.

In one embodiment of the invention it is provided that the curves are coupled to one another in a rotationally fixed manner and are preferably arranged on the same shaft. An advantage is that this enables precise coordination and exact synchronization of the movements of the tampon and the printing block (or the ink container, if this is driven).

In one embodiment of the invention, it is provided that the cam is formed by two cam disks arranged parallel to one another and adjustable relative to one another with respect to the axis of rotation of the cam, and that the two support rollers of the lever are in engagement with one of the cam disks. An advantage is that this facilitates such a setting that the lever is driven without play.

In one embodiment of the invention it is provided that the position of the pivot bearing of the lever is adjustable. An advantage is that this also facilitates the setting of a play-free drive for the lever.

In one embodiment of the invention it is provided that the hollow body has hard material on the circumference of its end face and / or that the hollow body is designed in the region of its end face in such a way that it can bend or twist in this region, and that the region mentioned is connected to the rest of the hollow body by a relative movement between the area of the end face and the rest of the hollow body, which permits relative movements between the area of the face and the rest of the hollow body.

One advantage is that the end face or the region of the hollow body which is directly adjacent to this end face can move relative to the other parts of the hollow body, so that the bending stiffness inherent in the hollow body, generally due to its tubular shape, is not transferred to the end face. The relative movement Permitting connection preferably also allows that the part bearing the end face can pivot relative to the other parts of the hollow body (paint container or pot) about several axes. Because the end face can perform the above-mentioned movements, it can easily follow a surface of the cliché that is uneven with high-precision steel clichés and adapt to this surface by bending and possibly twisting.

This advantage is particularly present when the paint container is held exclusively in the vicinity of its end face forming a wiping edge and thus the parts of the paint container above the area having the end face are not specially supported in parts of the machine. The advantageous properties of the invention can also be attributed in this case to the fact that, because of the bendability and twistability of the part of the paint container which has the end face compared to the other parts in the case of rapid twisting or swiveling movements of the end face, the other parts of the paint container do not have to follow these movements, so that the mass inertia or the moment of inertia of the upper parts of the paint container does not constitute an obstacle to the end face quickly adapting to the slight unevenness of the surface of the plate.

The invention makes the pad printing machine and the ink container not only more suitable for processing plastic plates, but also for the use of steel plates, because the front surface of the ink container can easily follow any existing unevenness of the surface of the steel plate even with steel plates and therefore the abrasive effect of a hard material end face, which is preferably coated with hard metal or other hard materials, is reduced to the cliché, thereby increasing its service life.

In general, it is sufficient if the ratio of the diameter of the end faces (with an annular end face) to the possible twisting (maximum deviation of the cliché from the completely flat shape) is about 300 to 1500 when using plastic clichés, and about 1000 when using steel clichés to 5000. Within the latter range there is, for example, a pot (ink container) with a 60 mm diameter of the end face, which can twist by 0.02 mm in the longitudinal direction of the pot and thus at right angles to the surface of the plate.

The inventive design of the paint container can be achieved in different ways. In one embodiment of the invention it is provided that the connection is formed by regions of the hollow body which are inclined at an angle different from 0 ° with respect to the longitudinal axis of the hollow body which is perpendicular to the cliché surface. The named areas, which understandably also have to be made sufficiently thin, form a type of membrane which enables the area having the end face to be bent and pivoted relative to the other parts of the paint container.

In one embodiment of the invention it is provided that the areas running at an angle are bellows-shaped. Here, several regions running essentially transversely to the above-mentioned longitudinal direction of the hollow body are connected in series.

In one embodiment of the invention it is provided that the region of the hollow body which has the end face is connected to the remaining parts of the hollow body with the interposition of at least one elastic part made of rubber or plastic. In particular, parts which were originally produced separately can be connected to one another by the elastic part.

In one embodiment of the invention it is provided that the pressing device has three points which act on corresponding upward-facing surfaces of the hollow body and which are arranged on a pressing ring to which a pressing force is applied at two points of a diameter line. One advantage is that this type of introduction of the contact pressure into the end face presses it against the cliché at three points, which favors the adaptation to an uneven cliché surface. The three points are preferably distributed evenly (at 120 °) around the circumference. It is advantageous if the three points are subjected to approximately the same force. For this purpose, it is advantageous if the pressure ring is largely rigid and the forces introduced into it at two points are the same. Furthermore, it is advantageous for this if the diameter line mentioned is offset by 30 from one of the points distributed among 120.

Instead of pressing the pressure ring against the part bearing the end face at three points which are rigidly connected to the pressure ring, a pressure force can be exerted on this part at more than three points. The forces are then introduced via elastic elements, in particular individual springs, or also through a single elastic, for example rubber-elastic ring arranged on the pressure ring, for example in the form of an O-ring. In this case, the contact pressure is introduced into the end face at an infinite number of points, as a result it can adapt perfectly to the cliché surface.

• Fig.1 eine perspektivische Darstellung eines Farbbehälters,
• Fig. 2 einen Längsschnitt durch den Farbbehälter nach Fig. 1,
• Fig. 3 einen Schnitt gemäß der Linie 111-111 in Fig. 2,
• Fig. 4 bis 6 andere Ausführungformen eines Farbbehälters im Längsschnitt,
• Fig. 7 in einem Schnitt VII-VII in Fig. 8 eine Seitenansicht der wesentlichen Teile einer Tampondruckmaschine ohne die Einzelheiten der Befestigung des Farbbehälters,
• Fig. 8 eine Draufsicht auf die Maschine nach Fig. 7,
• Fig. 9 eine Ansicht der Maschine der Fig. 7 von links in Fig. 7, teilweise abgebrochen,
• Fig. 10 Einzelheiten der Anpreßvorrichtung für den Farbbehälter in Seitenansicht,
• Fig. 11 einen Schnitt entsprechend der Linie XI-XI in Fig. 10,
• Fig. 12 eine Vorderansicht von links in Fig. 10.

Further features and advantages of the invention result from the following description of exemplary embodiments of the invention with reference to the drawing, which shows details essential to the invention, and from the claims. The individual features can each be implemented individually or in groups in any combination in one embodiment of the invention. Show it

• 1 is a perspective view of a paint container,
• 2 shows a longitudinal section through the paint container according to FIG. 1,
• 3 shows a section along the line 111-111 in FIG. 2,
• 4 to 6 other embodiments of a paint container in longitudinal section,
• 7 in a section VII-VII in Fig. 8 is a side view of the essential parts of a pad printing machine without the details of the attachment of the ink container,
• 8 is a plan view of the machine of FIG. 7,
• 9 is a view of the machine of FIG. 7 from the left in FIG. 7, partially broken away,
• 10 details of the pressing device for the paint container in side view,
• 11 shows a section along the line XI-XI in FIG. 10,
• 12 is a left front view in FIG. 10.

The drawings are largely schematic; only the details necessary for understanding the invention are shown. The sliding guide for the plate or the plate holder is not shown for simplification.

A paint container 1 according to FIGS. 1 and 2 is open at its lower end and there has a lower area 5, into which a shaped piece 8 is inserted, which consists of hard metal. The insert 8 ends at the bottom in a narrow end face 10, which strips off excess ink during the relative movement between the cliché and the ink container 1 when inking a cliché having depressions by means of pasty printing ink, which is located inside the container 1, and thus the effect of a doctor blade Has. The lower area 5 including the insert 8 is dimensioned such that it is slightly bendable and twistable, to the extent described at the outset, which corresponds to the unevenness or ripple of a cliché to be processed. So that the lower area 5 is not stiffened in an undesired manner by relatively rigid parts 16 of the paint container 1 arranged above it, the lower area 5 is connected to the upper area 16 by a membrane-like part which is made in one piece with the part 16 and is transverse to the one shown in FIG 2 connected transition piece 20 running from bottom to top longitudinal axis of the paint container 1, which has a smaller thickness than the area 16 and acts as a flexible membrane which does not result in any significant stiffening of the lower area 5. The lower region 5 can thus twist in itself and can also pivot about several axes relative to the upper region 16. A cover 22 is placed on the paint container 1 to prevent the evaporation of a solvent and the penetration of dirt into the paint.

Fig. 3 shows three contact surfaces 26 for two pins 32 (Fig. 10) of a pressure ring 34 on a circumferential edge 28. So that the ink container 1 can be separated from the pressure ring 34 if necessary, the edge 28 has three recesses 30, which it after a corresponding rotation of the pressure ring 34 allow the ink container 1 to be removed upwards. As will be explained later, two pressure pins 94 (FIG. 12) loaded by a spring act on the pressure ring 34, the connecting line of which is rotated by an angle of approximately 30 relative to one of the surfaces 26.

In the embodiment according to FIG. 4, the lower area 5 of the upper part of the paint container 1 ', designated here by the reference number 16', is connected by a bellows-like wall 40 with a small thickness, which likewise enables the lower area 5 to be freely pivoted and twisted.

In the embodiment according to FIG. 5, the lower region 5 'is produced as a part separate from the remaining part of the paint container 1 "and engages with an upwardly projecting tubular projection 42 in a downwardly open annular groove 44 of the upper container part 46. In the annular groove 44 an elastic seal 48 in the form of an O-ring is inserted above the pipe section 42. This O-ring is compressible somewhat because it does not completely fill the space provided for it, so that the decoupling between the lower area and the upper area 46 of the paint container 1 "is guaranteed.

In the embodiment according to FIG. 6, an upper region 46 "is connected to a separately produced lower region 5" by a vulcanized sleeve 50 made of rubber-elastic material, in particular plastic or rubber, through which the elastic connection with the lower area 5 "is effected.

The tampon printing machine shown in FIGS. 7 to 9 has a machine frame essentially formed by two side plates 60 and 61, in which an axle bolt 64 is mounted, on which a first lever 66 and a second lever 68 are rotatably mounted. The first lever 66 is used to drive a cliché carrier 69, which is displaceably mounted in a manner not shown, on which a cliché 70 is detachably fastened, in the horizontal direction. The second lever 68 is used to drive the tampon 72 in the vertical direction, which is guided displaceably in a guide 73.

The first lever 66 has two support rollers 7 and 71, each of which cooperates with an associated cam disk 76 or 77, which is fastened in a rotationally fixed manner on a shaft 75, in such a way that they bear against an outer surface of the cam disks running parallel to the longitudinal direction of the shaft 75. The cam disks 76 and 77 can be rotated relative to one another and can be locked on the shaft 75, so that with a suitable curve shape of the cam disks 76, 77 there is a positive control for the respective position of the first lever 66, any unwanted play being prevented. If desired, the axle pin 64 can be arranged on a holder which is adjustable relative to the machine frame, so that the goal of freedom from play can also be achieved or more easily achieved by changing the position of the pivot axis of the lever 66. In such a case, it can be expedient to provide a separate pivot bearing for the second lever 68, which can be changed independently of the pivot bearing of the first lever 66, if necessary. When the shaft 75 rotates, the first lever 66 is pivoted back and forth by the cams 76, 77. A bolt connected to the cliché or to a carrier of the cliché 70 preferably engages in an elongated hole 78 provided at the lower end of the first lever 66 using a so-called sliding block. Instead of disk curves, groove curves could be used if necessary.

On the shaft 75 there are also cam disks 86 and 87, which engage with support rollers 80, 81 of the second lever 68 and drive them in a manner similar to that described for driving the first lever 66. The cams 86, 78 are mutually adjustable and lockable. Since the cam disks 76, 77, 86, 87 are fixed in a rotationally fixed manner on the shaft 75, there is a phase-locked relationship between the drive of the cliché 70 and the tampon 72. The manner in which the shaft 75 is driven is not shown in the drawing for simplification . The shaft 75 can be guided through one of the side walls 60, 61 and can be coupled there to a drive motor, or can be provided with a gearwheel that is coupled in a rotationally rigid manner to a drive device of a production line.

The ink container 1 is at a standstill when the machine is operating. It is pressed with its end face against the cliché by a pressing device shown in FIGS. 10 to 12. The pressing device has two angular levers 90, 91 which are arranged at a distance from one another and parallel to one another, the arms of which protrude upwards are loosely connected to one another by a rod 92, to which a tension spring 93 acts exactly in the middle, the effective length and thus tension by an adjusting device 97 is changeable. The two other arms of the two levers 90, 91, which run approximately horizontally during operation, each carry a horizontally extending pin 94, the two pins 94 being directed towards one another. During operation of the machine, these pins 94 rest on an abutment surface 96, which is designed as a notch in the example, at two diametrically opposite points of the ring 34 on its upper side. The connecting line of the pins 94 is offset at an angle of 30 with respect to two of the pins 32. Since the levers 90 can pivot somewhat against each other because of the loose connection by the rod, both pins 94 are always subjected to the same force.

In operation, the arms of the levers 90, 91 which project upward do not rest against associated switching cams 98 which are in drive connection with a hand lever 100 via a shaft 102. If the hand lever 100 is rotated, the switching cams 98 and the levers 90, 91 assume the positions shown in broken lines in FIG. 10, as a result of which the pins 96 stand out from the ring 34, so that the container 1 together with the ring 34 is removed the area of the pressing device can be pushed away.

To remove the container 1 from the machine, an attachment piece is provided which is magnetically attached to a machine part and whose surface is exactly aligned with the surface of the cliché. The paint container 1 can then be pushed onto this extension without the paint flowing out, and then the container together with the extension can be removed from the machine. In the same way, another container that is either freshly filled or filled with a different color can be removed is used in the machine. Since the paint container is almost completely free in the machine, it is easily accessible for the change described. Several containers can be kept in stock, these can have different diameters of their downwardly projecting end faces and still with the same pressing device against the cliché are pressed. The cliché 70 can also be detached from its support and removed from the machine together with the ink container standing on it.

By means of the spring 93, which can be changed in its tension, the contact pressure with which the ink container is pressed against the cliché can be changed continuously and can thereby be adapted to the cliché used and its material.

As a drive for the machine, in addition to the possibilities mentioned above, a frequency-controlled motor or a chain can be used, by means of which the machine can be coupled to other devices and machines in a production line.

The cam disks driving the tampon are preferably designed in such a way that the tampon 72, after it has removed the ink from the cliché, which occurs when the cliché has been pushed to the left into the dash-dotted position compared to FIG. 7, before Printing on an object to be printed remains in the air for as long as possible because it has been shown that in this case the color is transferred particularly well to the object to be printed. The cam disks make it possible without difficulty to make the period within which the ink is transferred from the cliché as short as possible and to make the time that elapses until the tampon touches the object to be printed as long as possible.

If plastic plates are to be processed, the surface of the ink container in contact with the plate can be made of steel, preferably tool steel. Other materials are also possible. In other cases, it is expedient to provide this part of the paint container with hard material at least in the area of its surface. An insert 8 made entirely of hard metal can also have the required flexibility if dimensioned accordingly.

The kinematics described for the drive of the cliché and the tampon can be used for different sizes of the machine. According to current considerations, sizes of the machine in the range between a length of approximately 35 cm to approximately 100 cm are possible. The other dimensions result approximately from the figures 7 to 9, which are roughly to scale in this respect.

In the example, the insert 8, which has the end face (wiper lip or squeegee edge), is made of hard metal. It has an outer diameter of approximately 64 mm and an inner diameter of approximately 59 mm. Its height is about 5 mm.

It can be expected that cycle speeds of approximately 10,000 to 12,000 cycles per hour can be achieved with the construction according to the invention.

Because of the pivotability and twistability of the lower region of the paint pot or paint container, a lower contact pressure is required in the invention than in conventional machines. The machine according to the invention and the ink container according to the invention are therefore suitable for greater working speeds in comparison with the prior art and lead to a longer service life of the clichés.

The above-described pressing of the scraper edge against the cliché at a very large number of places by means of an elastic annular element arranged on the press ring is particularly suitable if the paint container has an end face with a relatively narrow free cross section, for example in the form of a narrow rectangle, the narrow side of which runs in the direction of the movement of the cliché, or in the form of a narrow ellipse.

Claims (5)

1. Pad printing machine with a holder for a cliché, with an ink supply device having a hollow body (1), the hollow body (1) resting with its end face (10) on the cliché (70) when the machine is working, with a pressing device for pressing on the end face of the hollow body against the cliché, with a device for generating a relative movement between the cliché and the hollow body, and with a tampon (72) which can be pressed onto the inked cliché and which absorbs the color from the recesses of the cliché and towards one transfers printing object, characterized in that the drive device for the relative movement between the hollow body (1) and the cliché (70) has a rotationally drivable curve (76, 77), that a pivotably mounted lever (66) has two support rollers (7, 71 ), which are engaged with the curve, such that the lever (66) swings through the curve in both pivot directions is conceivable, and that the part to be moved is coupled to the lever. 2. Pad printing machine, in particular according to claim 1, with a holder for a cliché, with a hollow body (1) having ink supply device, the hollow body (1) resting on the cliché with its end face (10) when working with the machine Pressure device for pressing the end face of the hollow body against the cliché (70), with a device for generating a relative movement between the cliché and the hollow body, and with a tampon (72) which can be pressed onto the inked cliché and which absorbs the color from the recesses of the cliché and transfers it to an object to be printed, characterized in that a drive device for the tampon (72) a rotatably drivable curve (86, 87) has that a pivoted lever (68) has two support rollers (80, 81) which are engaged with the curve, such that the lever (68) through the curve in both pivot directions is pivotable, and that the tampon (72) is coupled to the lever. 3. Machine according to claim 1 and / or 2, characterized in that the curves (76, 77; 86, 87) are rotatably coupled together and are preferably arranged on the same shaft. 4. Machine according to one of the preceding claims, characterized in that the curve (76, 77; 86, 87) is formed by two parallel to each other, relative to each other with respect to the axis of rotation of the curve adjustable cams, and that the two support rollers of the lever with one of the cams is engaged. 5. Machine according to one of the preceding claims, characterized in that the position of the pivot bearing of the lever is adjustable.

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