GB2040227A

GB2040227A - Screen printing machine with a rotatable stencil

Info

Publication number: GB2040227A
Application number: GB8000738A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-01-11
Filing date: 1980-01-09
Publication date: 1980-08-28
Also published as: DE2900829C2; NL8000024A; GB2040227B; IT1136100B; AT375878B; DE2900829A1; IT8012409A0; ATA816479A; CH644796A5

Abstract

A screen printing machine having a rotatable stencil 4 and an applicator roller 5 which is mounted rotatably in the interior of the stencil 4 and whose shaft journals 50 are passed through side mounting heads 30, 31 of the stencil, wherein the stencil can be separated from its mountings in the side mounting heads, by means of both shaft journals 50 being releasably connected to the applicator roller 5. By engaging the released roller 5 with lifting hooks 80, the roller 5, carrying with it the stencil 4 released from the side mounting heads, can be removed from the machine. <IMAGE>

Description

SPECIFICATION Screen printing machine with a rotatable stencil The invention relates to a screen printing machine having a rotatable stencil and an applicator roller which is mounted rotatably in the interior of the stencil and whose shaft journals are passed through side mounting heads of the stencil, which stencil can be separated from its mountings in side mounting heads of the machine.

A screen printing machine of this kind, with a rotatable stencil, has been proposed in DAS No. 20 35 220. In this proposed screen printing machine, when the stencil is to be changed, the applicator roll must firstly be released from its mountings and then drawn out through one of the side mounting heads.

This operation involves certain difficulties particularly when the machine is of large working width.

Operators have therefore changed over to a method which involves lifting the assembled stencil with applicator roller and side mounting heads, by a lifting means, and moving it to a cleaning station in which the special tool for extracting the applicator roller is also provided. However, before each change of stencil, the applicator roller must in any case be completely removed, at the cleaning station, before the stencil, being releasably mounted in the side mounting heads, can be replaced or cleaned.

In order to solve this problem, it has been proposed that the mountings of the screen printing stencil may be of a U-shaped configuration, the stencil heads being fitted into the upwardly open mountings and being tightened to the mountings.

The serious disadvantage of this proposal is that this manner of mounting the stencil leads to difficulties with regard to satisfactory rotational truth and with regard to precisely fixing the stencil in its working position.

The present invention is based on the problem, while maintaining the mounting of the stencil in side mounting heads which are preferably closed, of permitting replacement of the stencil, inspite of the squeegee roller disposed in the interior thereof, without the side mounting heads having to be released from their support and without the applicator roller having to be completely drawn out through one of the side mounting heads.

Accordingly the present invention provides a screen printing machine having a rotatable stencil and an applicator roller which is mounted rotatably in the interior of the stencil and whose shaft journals are passed through side mounting heads of the stencil, wherein the stencil can be separated from its mountings in the side mounting heads, by means of both shaft journals being releasably connected to the applicator roller. This arrangement therefore makes it possible for the shaft journals to be released from the applicator roller and for the applicator roller to be lifted with a lifting means, and, afterthe stencil has been separated from its side mounting heads, for the applicator roller together with the stencil to be taken to the washing station, with a lifting means.This therefore provides a considerable saving of time for cleaning and dis mantling the printing mechanisms, it is no longer necessary to transport heavy weights, and the replacement time is extremely short. This arrange ment retains the advantage of the optimum manner of mounting the stencil in side mounting the stencil in side mounting heads so that the side mounting heads can be of a robust construction, thereby providing excellent production conditions.

A further very important concept provides that the shaft journals are secured to the applicator roller so that they can be axially withdrawn. This therefore provides a very simple releasable connection between the shaft journals and the applicator roller, which can be employed with comparatively little problem.

A further very important concept of the invention provides that the separating lines between the hub portions of the applicator roller and the shaft journals are respectively disposed between the closed part of the stencil and ring and the side mounting head. In this arrangement, the separating lines between the shaft journals and the applicator roller are disposed in the region in which the stencil is also separated from its side mounting heads, so that there is a general separating line at that position, and both stencil and applicator roller can be lifted out of the machine.

A concept of the invention further provides that the shaft journals are respectively mounted in such a way that they can be extracted from a hub portion or the applicator roller, the applicator roller with its hub portions being of smaller length than the distance between the side mounting heads. When the hub portions have remained and the shaft journals have been drawn out or removed, this arrangement permits convenient manipulation between the side mounting heads, while the applicator roller and the stencil can be lifted out between the side mounting heads, for example by a lifting means.

For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: -Figure 1 is a view of a screen printing machine according to the invention in cross section through a printing station, Figure 2 is a side view of a printing station of the screen printing machine of Figure 1, Figure 3 is a perspective view of a detail of one side of a stencil mounting arrangement of the machine of Figures 1 and 2, Figure 4 is a view in partial section of one end of an applicator roller of the machine of Figures 1 to 3, in the working position, Figure 5 shows the Figure 4 construction in the dismantled position, Figure 6 is a diagrammatic end view of the mounting of the applicator roller, and Figures 7 and 8 show a dismantling station for stencil replacement, in two different working positions, also in diagrammatic form.

As will be seen from Figure 1, a screen printing machine 1 according to the invention firstly comprises a machine frame 2 and one or more printing stations 3 which are disposed thereon and in each of which a respective rotatable stencil 4 is mounted between two side mounting heads 30 and 31.

Disposed in the interior of the stencil 4 is an applicator roller 5 having shaft journals 50 which are passed through the side mounting heads 30 and 31, being carried at both sides in swing bearings 130 and 131. The swing bearings 130 and 131 are each fixedly connected to the side mounting heads 30 and 31. Drive gearwheels 60 and 61 for the applicator roller may be associated with the swing bearings 130 and 131. The drive gear wheels 60 and 61 may be driven by a transmission means 6, the torque being transmitted from one side to the other by way of the applicator roller 5.

In the embodiment illustrated in Figure 1,theweb of material 7 is passed through below the stencil 4, the web of material preferably lying on a printing blanket 70 which in turn is supported on a counterpressure beam 20.

The stencil 4 is in turn mounted releasably by the side mounting heads, in per se known manner. In the embodiment illustrated, the stencil mounting is by means of pin members 144 which are each arranged in pairs in the stencil end rings 44 and which can each be fixed in a respective drive sleeve 230 and 231 respectively. The drive sleeve 230 and 231 form part of the side mounting heads 30 and 31. Mounting the stencil 4 in this way is known per se. Figure 3 shows the mounting arrangement in greater detail.

In the example showing the mounting of the stencil at the drive sleeve 231, by axial displacement of the side mounting heads 30 and 31 towards each other, it is possible to free the heads of the pin members 144 so that the stencil 4 can be lifted, preferably upwardly, out of the slots 300 which are disposed parallel to each other. For this purpose, the stencil 4 must obviously be turned into the right position.

This however is also known. The possibility of separating the stencil from its mountings in the side mounting heads may also be achieved in a different manner from that illustrated. However, the construction illustrated has been found to be satisfactory in practice.

It is essential, in the subject of the invention as illustrated, for both shaft journals 50 of the applicator roller to be releasably connected thereto. In this respect, it is advantageous for the shaft journals 50 to be secured to the applicator roller in such a way that they can be withdrawn axially, as shown in Figures 4 and 5. For this purpose, the shaft journals 50 are mounted by means of a splined or grooved shaft 350 in an opening 351 in a hub portion 51 of the applicator roller 5, the hub portion 51 preferably having an annular groove 151 which is intended to lie outside the end rings 44 of the stencil 4, with a respective crane hook 80 which forms part of a lifting mechanism 8 being capable of engaging into each of the annular grooves 151 (see Figure 7).Axial displaceability of the shaft journals 50 can be achieved by engagement of a splined shaft or the like into the respective associated hub portion 51, while the arresting or locking means can be provided in the region of the mounting 130 and 131 respectively.

Here there is a sliding sleeve 32 through which an arresting pin 52 can engage into a groove 150 at the end of the shaft journal 50, the sliding sleeve 32 itself being mounted in a swing ball bearing 330. In order further to secure the components in position relative to each other, it is possible for a screw 55 which is fixed in the hub portion 51 to be taken through the entire shaft journal 50. The screw 55 automatically rotates when the applicator roller 5 is rotated.

Splines 250 of the splined shaft 350 ensure that the applicator roller 5 is entrained when the gearwheel 60 is rotated by the main drive or the transmission means 6.

The swing bearings 130 and 131 are disposed on the outside on the side mounting heads 30 and 31 and form a bridge arrangement between components of the side mounting heads 30 and 31. The bridge arrangement is supported at one end on a pivot pin 33 and at the other end on an adjusting bolt 34. By adjusting the bolt 34, the bearing 131 or asp the bearing 130 can be precisely adjusted so that the peripheral surface of the applicator roller 5 can be set precisely with respect to the stencil 4.

In order now to permit the stencil 4 to be easily removed, the spacing a, namely the spacing of the crane hooks 80 relative to each other, must be less than the spacing of the side mounting heads 30 and 31 from each other. This distance is indicated by b in Figure 1. The difference here should be of such an extent as to permit the applicator roller 5 with the stencil 4 hanging thereon to be easily lifted out.

The mode of operation of the apparatus is as follows: After the print or a printing operation has been concluded, the side mounting heads 30 and 31 are lifted or lift themselves out of the printing position, namely, by actuation of the cylinders 430 and 431, two such cylinders being provided in each side mounting head. This causes support bolts 530 to be extended, at all four corners of a printing station.

After the printing station has been raised, as shown in Figure 2, the stencil is rotated into a position, as shown in Figure 3, namely in which the slots 300 face upwardly. The applicator roller 5 is then supported in some manner, for example by being hung on the crane hooks 80 or by pushing two members underneath, so that in any event the applicator roller 5 or the hub portions 51 are supported. The side mounting heads are then lowered again, namely by being released by the cylinders 430 and 431 respectively.

When this occurs, the swing bearings 130 and 131 respectively move upwardly and there is no longer any load on the shaft journals 50. The shaft journals can then be drawn out by releasing the locking pins 52 and moving the shaft journals from a position as shown in Figure 4 into a position as shown in Figure 5. The applicator roller 5 is either supported on support means which are inserted thereunder or is already suspended from the crane hooks 80. if the applicator roller 5 is supported on support means thereunder, the crane hooks 80 must now be engaged therewith, and slightly raised. The support means under the applicator roller are then removed.

In this position, the stencil is still connected to the side mounting heads 30 and 31. The side mounting heads are then moved towards each other so that the pin members 144 provided with heads are released from their locked position in the respectively associated drive sleeves 230 and 231, and the applicator roller 5 with the stencil 4 can then be lifted out of the machine and moved to a dismantling station which is shown in Figures 7 and 8. Figure 7 shows the position when the assembly is moved into dismantling station; support pin members 90 which form part of the dismantling apparatus 9 can be inserted into the openings provided in the hub portions 51.

In order to permit the second movable dismantling stand 92 to be taken away, a support leg 91 can also be provided at a central position, which support leg 91 can be put into position only when the stencil has been pulled away in the direction indicated by the arrow.

As will be apparent from the description, the subject of this invention is not limited to the embodiment illustrated, so that variations are conceivable and possible. However, the illustrated manner of securing the shaft journals 50 to the hub portions 51, by simply pulling them out, is particularly advantageous and does not give rise to any serious technical problems.

Claims

1. A screen printing machine having a rotatable stencil and an applicator roller which is mounted rotatably in the interior of the stencil and whose shaft journals are passed through side mounting heads of the stencil, wherein the stencil can be separated from its mountings in the side mounting heads, by means of both shaft journals being releasably connected to the applicator roller.

2. A screen printing machine according to claim 1, in which the shaft journals are secured to the applicator roller in such a way that they can be axially extracted.

3. A screen printing machine according to claim 1 or claim 2, in which the shaft journals are each mounted so that they can be retracted from a hub portion of the applicator roller.

4. A screen printing machine according to claim 1, in which the separating lines between hub portions of the applicator roller and the shaft journals are respectively disposed between a closed part of a stencil end ring and the respectively associated side mounting head.

5. A screen printing machine according to claim 4, in which the separating lines of the applicator roller are closer to each other, being at spacing (a), than the spacing (b) of the side mounting heads from each other.

6. A screen printing machine according to claim 5, in which the separating line between the applica tor roller and the shaft journal is disposed in the approximate region of the separating line between the stencil and the side mounting head.

7. A screen printing machine according to claim 3, in which securing means for engagement by a lifting means or by crane hooks are provided on the applicator roller.

8. A screen printing machine according to claim 7, wherein the securing means is a groove.

9. A screen printing machine according to claim 7 or claim 8, wherein the securing means is provided on the hub portion of the applicator roller.

10. Ascreen printing machine according to claim 1, in which the shaft journals carry at their ends a splined shaft or the like, which respectively engage into a corresponding opening in the applicator roller or in a hub portion of the applicator roller respectively.

11. A screen printing machine according to claim 1, in which the shaft journals are each mounted in respective swing bearings secured to the side mounting heads.

12. A screen printing machine according to claim 9, in which sliding sleeves are arranged in the swing bearings, for axial displacement of the shaft journals and arresting means are provided for fixing the position of the shaft journals in the sliding sleeve.

13. A screen printing machine according to claim 1, in which the shaft journals are secured to the applicator roller or its hub portion by a respective axially disposed screw which is passed through a central bore.

14. A screen printing machine substantially as hereinbefore described with reference to the accompanying drawings.