Technical field:

This invention relates to an ink pan for printing machi¬ nes, especially flexo printing and rotogravure printing, which pan at least comprises parts which are intended to accomodate an amount of ink and means for supporting said ink pan.

The state of the art:

Accordingly, the invention relates to (here the precha- racterizing portion of claim 1 follows) an ink pan for printing machines intended for operation with rollers of varying sizes, especially flexo printing and rotogravure print, which ink pan at least comprises parts intended to accomodate an amount of ink and means for supporting said ink pan. Printing machines of the above-mentioned kind on the market today often use non-disposable ink pans. Such ink pans are accordingly made of a durable material, such as for example stainless steel. In connection witn a new printing operation where a new colour is to be used, the ink pan has to be totally clean. Therefore, it is usual that there is at least one supplementing ink pan ready, which has of course been cleaned. Due to their design, these ink pans are quite heavy and cumbersome to deal with.

Technical problem:

From the above-mentioned it is evident that this known system not only implies a direct cost in the form of long set-up times but also leads to an environmental problem since the ink pans are relatively heavy and therefore difficult to lift and since a relatively time-consuming cleaning of the ink pans is necessary. This latter causes

both an environmental problem as well as a problem of economical optimization. The problem of economical opti¬ mization depends on whether it is profitable to wash the ink pans when this is compared to other possible alternatives. Hitherto, the only possible alternative has been to throw away the ink pan instead of washing it. Since the production cost of such an ink pan is relati¬ vely high, this has not been an acceptable solution and there-fore washing has been the winning alternative.

Further, there is another economical problem in connec¬ tion with machines of above-mentioned kind, to which there has not been found any solution so far. As a matter of fact, a large number of differently sized rollers with varying circumference has to be used for one and the same printing machine. One and the same printing machine can accordingly at one moment be used together with a roller with a circumferential size of circa 500 mm whereas for the next operation it has a roller with a circumferential size of about 1000 mm. For both of these operations, however, one and the same ink pan is used. In order to obtain sufficient ink onto the roller it is necessary that the roller is submerged into the ink (which is con¬ tained in the ink pan) with a certain part of its cir- cumferential area. It is evident that when using the smaller roller it is necessary to fill the ink pan to a higher level than is the case during the operation with the bigger roller. When such an operation is terminated, a certain minimum amount of ink will always remain, which in most cases will be a lost amount. This lost amount leads to a non-desired extra cost.

Further, this known system charges the environment in a hard way since it leads to a lot of solvent being exposed to the environment. The solvent is partly exposed in connection with the operation of the printing machines,

since the surface of the ink pans are relatively large thereby exposing a large liquid surface area but most of all it is related to the cleaning of the ink pans, a cleaning which has to be made by assistance of strong solvent.

The solution and advantages:

The object of the present invention is to provide a printing machine which eliminates the above specified disadvantages.

Said object is achieved by means of a device in accord¬ ance with the invention, which is characterized in that the ink pan is made of a material which is suitable for being disposable, and preferably that said supporting means maintains the ink pan's relative position inde¬ pendently of the size of the volume which is accomodated by the ink accomodating parts of the ink pan, so that a simple feasible optimization of the volume of the ink accomodated in the pan is obtained during operation with differently sized rollers.

From US-A-4 580 495 there is known an ink pan for printing machines being of the disposable kind. This known ink pan, however, is of a totally different kind, which is not intended for the operation with rollers of varying diameters.

Brief description of the drawings: In the following the invention will be described in more detail, by way of example only, with reference to the drawings in which;

Fig. 1 shows a side view of the longer side of an ink pan in accordance with the invention.

Fig. 2 shows a side view of the shorter side of an ink pan in accordance with the invention,

Fig. 3 shows a second ink pan seen from the shorter side,

Fig. 4 shows parts of an ink pan seen from above, and the attachment device therefor,

Fig. 4b shows alternative attachment devices, seen from the side,

Fig. 5 shows a side part intended to be used together with the ink pan,

Fig. 6 shows a cross-section, of the short side, of a support for an ink pan in accordance with the invention,

Fig. 7 shows the same support as in Fig. 6, in a vertical cross-section.

Fig. 8 shows parts of said support seen from above,

Fig. 9 shows a preferred embodiment of the invention, and 10 and,

Fig. 11 shows the principal of operation of a device in accordance with the invention.

In the Fig. 1 and 2 there is ^' shown an ink pan 1 in accordance with the invention. The ink pan comprises two side portions 16,17 and a pan part 10 which extends therebetween. For letting out of the ink, the ink pan preferably has an outlet 12.

In Fig. 2 the principal positioning of the ink pan 1 is shown. The ink pan 1 is positioned adjacent to the printing roller 4. The ink pan 1 has as its object to allow the roller to rotate in ink 5. The ink can be kept at constant level, in the ink pan, by means of pumping an excessive amount into it, i.e. more than is being con¬ sumed, at the same time that one uses an outlet means which determines the level (not shown) . This outlet means can for instance comprise a pressure-sensing device, an overflow device or a level-determining positioning of the outlet device 12.

The surface of the pan 10 has a circle-like arch which is adapted to the outer surface 40 of the roller. Further, the ink pan has attachment means 13,14. These means consist in the shown embodiment of substantially plane surfaces which preferably are limited by downwardly directed tapered edges. These surfaces are preferably intended to interact with solid parts of the machine. The side portions 16,17 of the ink pan 1 also present centrally positioned recesses 11 in order to provide space for the shaft 41 of the roller 4. One of the ends 13 of the attachment means further is provided with re¬ cesses 15 in order to enable fitting of the ink pan 1 in connection with the mounting thereof into the machine. In Fig. 2 there is shown that this recess 15 is made by a depression of chosen parts, whereas under certain cir¬ cumstances it may be preferred to be arranged in the form of a through-hole, e.g. by means of punching.

In Fig. 3 there is shown an ink pan 1 in accordance with the invention but which has different dimensions compared to the ink pan in accordance with Fig. 2. The ink pan in accordance with Fig. 3 is namely adapted for use in connection with printing rollers 4 of larger circum¬ ference. As is illustrated in Fig. 3, the distance

between the two attachment means 13, 14, however, is the same in Fig. 2 and Fig. 3.

As has already been described, one and the same printing machine is used together with a number of rollers with different circumferences. In order to enable use of dis¬ posable pans but still always use the same attachment points, this requires that the pans are made in such a manner that they always can be attached at the same points.

This is easily achieved by attaching pans with different geometry 10 on supporting means 13,14 which has the same interrelated dimensions. The production of the pans can preferably either be made in a one-step process, e.g. hotpressing of a thermoplastic sheet, form moulding, etc or also in a two-step process where the ink pan 10 and the supporting means 13,14 respectively are first produced separately and thereafter joined.

In Fig. 4 the pan is shown from above but not the whole extension thereof. Fig. 4 shows how the pan 1 in an easy manner can be attached to the machine by means of preferably U-shaped clips 6. The ink pan has a recess 15 in order to provide space for one of the parts of the clips 6. Instead of using separate clips it may be advantageous to use a longish device (not shown) with a number of such clips 6 arranged thereon.

Another manner of solving the fitting is to, as is shown in Fig. 4b, use clips 60 whose inner portion 61 always interacts with the actual pan 10, enabling a number of differently sized clips 6 to be used. Further, parts of a support frame 22 are provided with adapters 62, whose size depends on the size of the roller, as does the size of the clips 60 too.

Fig. 5 shows a side piece 3 which, advantageously, is used in combination with an ink pan in accordance with the invention in order to secure it in a more stable manner. The side piece 3 is attached in an appropriate manner to the machine, one at each side of the ink pan 1. The side piece has a recess 31 which is adapted to the shaft 41 of the roller 4.

Fig. 6 shows a vertical cross-section of a supporting frame intended to be used in connection with the ink pan 1. This supporting frame 2 is adapted to be attached to the machine by means of an attachment device 26 and appropriately by means of attaching it to said side pieces 3. The frame 2 has two longitudinal beams 21,22 inter-connected with each other in an appropriate manner by means of transversal interconnecting means 23,24,25.

Fig. 7 shows the same frame seen in a vertical section from the side. The extension of the device of the frame 2 which supports the ink pan 1 is preferably of the same length as the ink pan 1.

Fig. 8 is a view of the same frame 2 seen from above. The distance between the two beams 21,22 and the locations of the interconnecting parts 23,24,25 should be adapted to the largest possible roller 4. If there is only suffi¬ cient space for the largest roller the adaption of the others can be made by the choice of ink pan.

When changing from the old system to the use of dis¬ posable ink pans in accordance with the invention, it is appropriate to proceed as follows. The first measure is to establish that it is possible to mount the ink pan in an appropriate manner 1. This is done either by arranging attachment means therefor 21,22 on the machine in an appropriate manner, or by providing a frame 2 (see Fig.

6,7 and 8) into which the ink pan 1 can be attached. In a preferred embodiment one uses a frame 2 which has attach¬ ment means 26 in order to be attached to the machine (not shown) . Thereafter one selects an ink pan 1 which is adapted to the circumference of the print roller 4 which is to be used. The supporting surfaces 13,14 of the ink pan is arranged so as to rest against the supporting parts 21,22 of the frame. When an appropriate distance, circa 7-10 mm, has been adjusted between the roller's periphery and the inner surface of the ink pan, the ink pan 1 is fixed by means of appropriate fixation means 6, which in the preferred embodiment consist of a longish part with a leg-like part intended to clamp the ink pan to the frame 22.

In Fig. 9 and 10 there is shown a preferred modification of the invention. Instead of only having the pan part exchangeable, one here also has an exchangeable frame construction. Similar to what has been described in Fig. 6,7 and 8 this frame construction 2 also presents U-like transverse interconnecting elements 23,24,25. Each frame 2 comprises three such U-like units. At the upper part of each such U there is attached a longish plate 27 thereto. This longish plate has at its lower part, by means of a welding 271 attached thereto, an inwardly directed part of its respective leg 23,25. Between the upper part of the plate 27 and the lower part there is a longitudinal fold 272, providing a certain adaptation of the inner surface of the plate to the outer surface of the pan 1. The upper part 271 of the plate presents a longish fold- together unit, where the upper part accordingly has been bent so that it contacts the outer surface of the plate in order to avoid that the sharp edge portion 273 comes into contact with the ink pan 1 and instead providing smoothly folded edge 274 as the upper part of the plate. At each interconnecting element 23,24,25 being positioned

at the outer locations there are attachment means 28A,28B at the surface, i.e. erected away from the centre of the ink pan. In the shown embodiment these are made by square tubes being welded to each respective leg 23,25. The tubes 28A,28B are substantially parallelly arranged and the distance L between the outer surfaces is a distance which is determined by the supporting device (not shown) of the machine on which the frame 2 is intended to be positioned. The distance L between the tubes 28 is accordingly determined by the design of the machine and is therefore independent of the size of the ink pan 1, in accordance with what has prior been described and which principle is an essential feature of the invention. By means of the latter described embodiment of the device in accordance with the invention one gains the advantage that the ink pan 1 can be made from a very thin material since the longish plates 27 support the ink pan in an advantageous manner. The tray 1 is produced in such a manner that protruding tongue-shaped parts 18 protrude at the upper edge areas. These tongue-shaped parts 18 are used in order to clamp the ink pan 1 to the frame 2 by means of clips 6. The tongues 18 and the ink pan 1 are separated by a folding line which is provided during the process of production, along which folding line the upper edge 274 of each plate 27 is intended to be arranged. The figure further presents a ring 70 with an outlet pipe 71 that is arranged at the outlet. The ring 70 is appro¬ priately attached to the interconnecting element 23,24,25 by means of attachment device and threaded means.

Fig. 10 shows a differently sized frame which is used together with the same machine as the one shown in Fig. 9. The frame shown in Fig. 10 is intended for use in operation with rollers having a smaller diameter than those used together with the frame shown in Fig. 9. As a consequence, the distance between the plates 27 of the

smaller frame (Fig. 10) is smaller than the distance between the plates 27 of the bigger frame (Fig. 9) . The distance between the attachment tubes 28A,28B, however, is the same as for the bigger frame. In order to obtain the correct distance L of the smaller frame, the tubes 28A,28B are attached to the outer surfaces (welded) of the interconnecting devices 23,24,25, whereas on the bigger frame (Fig. 9) they are welded with the end surface towards said interconnec-ting devices. If a still smaller frame is to be used than the one in Fig. 10, one has to use connection pieces, or similar means, in order to attach the tubes 28A,28B onto the units.

As has already been mentioned the loss of ink can be minimized by means of the invention, since the invention provides access to ink pans of different sizes whereby an appropriate combination of roller 4 and ink pan 1 can be chosen.

An optimal performance is, for one and the same machine that is intended for use together with a number of diffe¬ rent sized rollers, to group these together in appro¬ priate groups whereby each group is intended for a cer¬ tain size of ink pan so that a limited number of ink pans can be achieved.

For a machine where the smallest print roller had a cir¬ cumference of 530 mm and the largest print roller had a circumference of 930 mm it has been shown that a pre- ferred grouping contains four groups. The smallest size of the ink pan is hereby adapted ^' to the use for printing rollers with a circumference of 530 mm up to 600 mm. It is evident that the smallest loss is obtained when the machine is used together with the largest roller, 600 mm, and that the loss increases more the smaller the roller being used. It has been found that this optimal grouping

results in an increase of the loss from circa 12 kg to circa 15 kg when one starts with using the largest one and ends with using the smallest one within the respec¬ tive group. This should be put in relation to the total loss of at least 45 kg that had to be taken into account when using the old method with non-disposable ink pans.

The material being used in order to produce the pan 1 can be of any material known to the skilled man which will be suitable for the production of disposable units of this kind. The material must be relatively durable, so that the ink pans can be changed without the necessity of too much carefulness. Furthermore, the material should of course be non-permeable to liquids and also be resistant to solvent. Moreover it is desirable that the ink pan be relatively light so that preferably one man can exchange it without any extra lifting means. A further desire is that the cost for such an ink pan should be kept as low as possible, and therefore it is desired that the used material be not too expensive and most of all, easy to form. It is evident for the skilled man that there are several kinds of material that are suitable, most of all polymeric material, such as polyethylene, etc. For the preferred embodiment black impregnated polyethylene is used.

When the machine is to be used, (see Fig. 11) a receptacle 80 is positioned on a predetermined spot adjacent the machine. This container contains a (not shown) plastic vessel which contains the colour 5 that is to be used during the printing operation. By means of a flexible input tube 81A,B and a non-contacting pump 82, it is possible to pump the colour from the container 80 to the ink pan 1. Moreover, there is in a preferred embodiment, at the outlet 12 of the ink pan arranged an outlet tube 71 which leads down into said vessel 80.

During the printing operation one adds a continous ex¬ cessive flow of colour to the ink pan where a not shown levelling device insures that a constant level is maintained.

By means of a viscosity sensing meter 84 and a stirrer 85 and an inflow tube 83 for solvent, the viscosity of the ciruculating liquid 5 can be kept within certain levels during operation.

The invention is not limited by the above described but can be varied within the scope of the following claims. Accordingly, it is for example possible, instead of the almost circular cross-section of the ink pan, to have a form that deviates therefrom, such as an oval or discon¬ tinuous, ten-edged pan form.

Further, it is evident for the skilled man that it is easy to find substitutes for the above-described attach- ment means (the clips 6) . Accordingly, it would be possible to use some kind of resilient clamp, e.g. of the type that is known for attaching clothes to rope. Further, it is possible to use some kind of threaded means etc. Moreover, it is evident for the skilled man that said supporting means 13,14 do not have to be in one straight line as has been shown above but can be arranged in any other pattern if this is likely to give a better solution for support of the ink pan 1.

A further possible change would be to lower the level of the ink pan so that it could be placed underneath the level of the shaft 41 with its lower part whereby the recess therefore would be superfluous.

Furthermore, it is obvious for the skilled man that modifications can be made to the described frame 2 in

order to adapt this to certain needs, such as to make it supported by damping means of rubber if the vibrations cause problems. Finally, it is evident for the skilled man that especially the preferred embodiment of the invention, despite its preferred use for printing machine with rollers of different sizes, also advantageously can be used for printing machines that are not intended for use together with rollers of different sizes.