EP0315769B1 - Pad-printing machine - Google Patents

Abstract

A pad-printing machine possesses a holder for a printing block (70) and an ink supply device with a hollow body. When the machine is operating, the hollow body lies with its face area on the printing block. The hollow body (1) is constructed in the area of its face in such a way that it can bend or twist in this area and the said area is joined to the remainder of the hollow body by a connection which allows a relative movement between the face area and the remainder of the hollow body. In this way, the face area adapts itself to the surface of the printing 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 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 and transfers it to an object to be printed, the hollow body being hard on the circumference of its end face Has material.

Such a machine is known from EP-A-0 140 165 and from DE-A-22 05 430. 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.

Starting from DE-A-22 05 430, the invention has for its object to provide a machine of the type described above, which is suitable in principle for the use of plastic printing blocks, which generally have a greater deviation of their area from one level than high-precision manufactured Steel clichés. However, the advantages of the resistance of the end face to wear should be retained, so that, for example, the use of soft plastic for the end face is prohibited.

This object is achieved in that the hollow body is constructed from at least two sections, the one having the end face of the hollow body being designed in such a way that it can bend or twist, and in that the end face is connected to the other by an elastic connecting means Section of the hollow body is connected, wherein the elastic connecting means allows relative movements between the end face and the further section of the hollow body.

One advantage is that the end face or that 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 because of its sleeve shape, is not transferred to the end face. The connecting means permitting relative movements preferably also allow the part carrying the end face to pivot about several axes relative to the other parts of the hollow body (paint container or pot). This is because the end face is the one mentioned Movements, it can easily follow an uneven surface of the cliché to a greater extent than 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 hollow body is preferably finely machined on the circumference of its end face with a roughness depth of at most 2 μm.

Through the invention, the pad printing machine and the ink container are not only better suited 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 The effect of the end face comprising a hard material, which is preferably coated with hard metal or other hard materials, on the cliché is reduced, as a result of which its service life is increased.

In general, it is sufficient if the ratio of the end face diameter (with a circular end face) to the possible twisting (maximum deviation of the cliché from the completely flat shape) is about 300 to 1500 when using plastic plates, and about 1000 to 5000 when using steel plates Within the latter area 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 elastic connecting means is formed by sections of the hollow body which are inclined at an angle other than 0 ° with respect to the longitudinal axis of the hollow body which is perpendicular to the cliché surface. The sections mentioned, which understandably must also be made sufficiently thin, form a type of membrane which enables the part having the end face to be bent and pivoted relative to the other parts of the paint container.

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

In a further embodiment of the invention it is provided that the section 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 connecting means made of rubber or plastic. In particular, parts originally produced separately can be connected to one another by the elastic connecting means.

In an advantageous embodiment of the invention, it is provided that the pressing device has three attack elements, for example pins, acting on corresponding upward-facing surfaces of the hollow body, which are arranged on a pressing ring to which a pressing force is applied at two points on 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 it is favorable if the Pressure ring is largely rigid and the forces introduced into it at two points are the same. Furthermore, it is favorable for this if the diameter line mentioned is offset by 30 ° with respect to one of the points distributed at 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 introduction of the forces then takes place via elastic elements, in particular individual springs or also by a single elastic, e.g. elastic ring, e.g. in the form of an O-ring. In this case, the contact pressure is introduced into the end face at an infinite number of locations, which means that it can adapt perfectly to the surface of the cliché.

In one embodiment of the invention it is provided that the drive device for the relative movement between the cabbage body and the cliché 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 through the Curve is pivotable in both pivot 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.

In one embodiment of the invention it is provided that a drive device for the tampon has a rotationally drivable curve, that a pivotably mounted lever two Has support rollers which are engaged with the curve, such that the lever is pivotable in both pivot directions by the curve, and that the tampon is coupled to the lever. An advantage is that this enables simple actuation of the tampon.

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.

The machine with a mechanical drive for the tampon and for the relative movement between the cliché and the ink fountain has the machine with a pneumatic drive The advantage of this is that, because all movements are positively controlled, the machine can run particularly quickly, in particular because special sensors do not have to be used to determine whether certain machine parts have reached their desired position.

The invention also relates to a cabbage body for use in a pad printing machine. According to the invention, the hollow body is designed as described above. The advantages also come into play in connection with other machines.

Fig.1

eine perspektivische Darstellung eines ersten Ausführungsbeispiels eines Farbbehälters,

Fig. 2

einen Längsschnitt durch den Farbbehälter nach Fig. 1,

Fig. 3

einen Schnitt gemäß der Linie III-III 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

Fig. 1

1 shows a perspective illustration of a first exemplary embodiment of a paint container,

Fig. 2

2 shows a longitudinal section through the paint container according to FIG. 1,

Fig. 3

2 shows a section along the line III-III in FIG. 2,

4 to 6

other designs of a paint container in longitudinal section,

Fig. 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,

Fig. 8

7 shows a plan view of the machine according to FIG. 7,

Fig. 9

7 from the left in Fig. 7, partially broken away,

Fig. 10

Details of the pressing device for the paint container in side view,

Fig. 11

a section along the line XI-XI in Fig. 10,

Fig. 12

10 is a front view from the left 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 designed as a hollow body 1 according to FIGS. 1 and 2 is open at its lower end and there has a first section 5, into which an insert 8 is inserted, which consists of hard metal. The insert 8 ends at the bottom in a narrow end face 10, the excess ink when inking a cliché 70 having depressions (FIG. 10) by pasty printing ink, which is located inside the container 1, during the relative movement between the cliché 70 and the ink container scrapes and thus has the effect of a doctor blade. The first section 5 including the insert 8 is dimensioned so that it is slightly bendable and twistable, to the extent described at the outset, which corresponds to the unevenness or ripple of a cliché 70 to be processed. So that the first section 5 is not stiffened in an undesired manner by relatively rigid sections 16 of the hollow body 1 arranged above it, the first section 5 is connected to the further section 16 by a membrane-like part which is made in one piece with the section 16 and is transverse to the one shown in FIG 2 connected from the bottom upward extending longitudinal axis of the hollow body 1, formed as an elastic connecting means 20 transition piece, which has a smaller thickness than the section 16 and acts as a flexible membrane that does not result in any significant stiffening of the first section 5. The first section 5 can thus twist in itself and can also pivot about several axes relative to the further section 16. A cover 22 is placed on the hollow body 1 and is intended to prevent the evaporation of a solvent and the penetration of dirt into the paint.

Fig. 3 shows three contact surfaces 26 for three pins 32 (Fig. 10) of a pressure ring 34 on a circumferential edge 28. So that the hollow body 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 hollow body 1 to be removed upwards. As will be explained later, the pressure ring 34 in turn has two spring-loaded pins 94 (FIG. 12), the connecting line of which is rotated by an angle of approximately 30 ° with respect to one of the surfaces 26.

In the embodiment according to FIG. 4, the first section 5 is connected to the further section 16 ′ of the hollow body 1 ′, denoted here by the reference number 16 ′, by means of an elastic connecting means 40 with a small thickness, which is designed as a bellows-like wall, which is also freely pivotable and The first section 5 can be twisted.

In the embodiment according to FIG. 5, the first section 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 further section 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 somewhat deformable because it does not completely fill the space provided for it, which ensures the decoupling between the first section 5 'and the further section 46 of the hollow body 1' '.

In the embodiment according to FIG. 6, a further section 46 ″ is connected to a separately produced first section 5 ″ by an elastic connecting means 50 designed as a vulcanized sleeve made of rubber-elastic material, in particular plastic or rubber, through which the elastic connection with the first section 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 plate carrier 69, which is displaceably mounted in a manner not shown, on which a Cliché 70 is releasably attached 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 that 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 may be expedient to provide a separate pivot bearing for the second lever 68, which can be changed, if necessary, independently of the pivot bearing of the first lever 66. When the shaft 75 rotates, the first lever 66 is pivoted back and forth by the cams 76, 77. An elongated hole 78 provided at the lower end of the first lever 66 preferably engages with the cliché using what is known as a sliding block or a carrier of the cliché 70 connected bolts. 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 are directed towards each other. 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 from two of the pins 32 at an angle of 30 °. 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 hollow body 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 hollow body 1 can then be pushed onto this attachment piece without the paint flowing out, and the hollow body 1 together with the attachment piece can then be removed from the machine. In the same way, another hollow body, which is either freshly filled or filled with a different color, can be inserted into 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 be pressed against the cliché with the same pressing device. 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 in the dot-dash 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 to make the time period within which the ink is transferred from the cliché as short as possible and the period of time that elapses without difficulty. until the tampon touches the object to be printed, making it as long as possible.

If plastic printing blocks are to be used, the surface of the ink container in contact with the printing block 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 (wiping 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 first section of the paint pot or paint container, a lower contact pressure is required in the invention than in conventional machines. Therefore, the machine according to the invention and the ink container according to the invention in comparison with the prior art for greater working speeds and leads 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 (14)

1. Pad-printing machine with a support for a printing block (70), an ink supply arrangement including a hollow body (1) which lies, during operation of the machine, with its face (10) on the block (70), pressing means for pressing the face (10) of the hollow body (1) against the block (70), means for producing relative movement of the block (70) and the hollow body (1), and a printing-pad (72) which can be pressed against the inked block (70) so as to take up the ink from the depressions of the block (70) and to transfer it to an article to be printed, whereby the hollow body (1) is provided with hard material at the circumference of its face (10), characterised in that the hollow body (1) comprises at least two portions (5,5',5",16,16',46,46'), the first portion (5,5',5") with the face (10) of the hollow body (1) being so constructed that it can bend or twist, and the face (10) being connected to the other portion (16, 16', 46, 46') of the hollow body (1) by an elastic connecting means (20, 40, 48, 50), whereby the elastic connecting means (20, 40, 48, 50) permits relative movement between the face (10) and the other portion (16, 16', 46, 46') of the hollow body (1).
2. Machine as claimed in Claim 1, characterised in that in the case of a circular face (10) the ratio of the diameter of the face (10) to the possible displacement of the face (10) lies between 300 and 5000.
3. Machine as claimed in Claim 1 or Claim 2, characterised in that the elastic connection means forms a portion of the hollow body (1) which is inclined with respect to the longitudinal axis of the hollow body (1).
4. Machine as claimed in Claim 3, characterised in that the inclined portion has a concertina form.
5. Machine as claimed in one of the preceding claims, characterised in that the elastic connecting means comprises an intermediate piece (48, 50) of rubber or plastics.
6. Machine as claimed in one of the preceding claims, characterised in that the pressing means includes three contact elements, e.g. pegs (32), which act on corresponding upwardly-facing surfaces of the hollow body, the contact elements being arranged on a pressing ring (34) on which a pressing force is applied at two points on a diameter.
7. Machine as claimed in Claim 6, characterised in that the three contact elements, e.g. pegs (32), are equally spaced (at 120° intervals) around the circumference.
8. Machine as claimed in one of Claims 1 to 5, characterised in that the pressing ring (34) acts on the face-carrying part at more than three points in the intermediate position of at least one elastic element.
9. Machine as claimed in any one of the preceding Claims, characterised in that the means for producing relative motion between the hollow body (1) and the pad (2) includes a rotatably drivable curved member (76, 66), in that a pivotally mounted lever (66) is provided with two support rollers (70, 71), which cooperate with the curved member (76, 77) such that the lever (66) can be pivoted by the curved member (76, 77) in both directions, and in that the part to be moved is coupled to the lever (66).
10. Machine as claimed in any one of the preceding Claims, characterised in that the means for moving the pad (72) comprises a rotatably drivable curved member (86, 87), in that a pivotally mounted lever (68) is provided with two support rollers (80, 81) which cooperate with the curved member such that the lever (68) can be pivoted by the curved member in both directions, and in that the pad (72) is coupled to the lever (68).
11. Machine as claimed in Claim 9 and Claim 10, characterised in that the curved members (76, 77 and 86, 87) are coupled together and are preferably arranged on the same shaft.
12. Machine as claimed in at least one of Claims 8 to 11, characterised in that the curved member (76, 77, 86, 87) comprises two curved discs arranged parallel to each other and displaceable relative to each other along the axis of rotation of the curved member (76, 77, 86, 87), and in that the two support rollers of the lever each cooperate with one of the discs.
13. Machine as claimed in Claim 9 or Claim 10, characterised in that the pivot point of the lever is variable.
14. Hollow body for use in a pad-printing machine as claimed in any one of the preceding claims, characterised by the construction defined in one of Claims 1 to 5.

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