DK149710B - METHOD AND APPARATUS FOR PAINTING CYLINDRICAL HOLIDAYS SUCH AS DAISY TOPICS - Google Patents

Description

in 149710 o

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a method and apparatus for painting the circumference of cylindrical hollow bodies, such as can blanks, wherein the hollow bodies are held rotatably about their longitudinal axis rotatable mandrels on a drawn mandrel wheel and pressed against a drawn mandrel wheel axis parallel paint roller in a paintwork and in a touch mill. the lacquer roller together with the mandrels is guided along the contour of the roller, and where the hollow bodies and lacquer roller are driven separately at different circumferential speeds.

Lacquering the circumference of cylindrical hollow bodies, e.g. Canned blanks are by the aforementioned known method in that the rotating mandrels of the orbital mandrel-drawn hollow body together with the mandrels are set in a rotational motion so that the circumferential velocity of the hollow bodies in the contact zone with the varnish roller is the same as the circumferential velocity of the varnish , so that the hollow body and the lacquer roller roll on each other and a lacquer transfer from the roller to the hollow body occurs under the influence of the pressure between the hollow body and the lacquer roller. In order to obtain a 20 closed and most uniform lacquer application to the hollow body, the contact is maintained for a period corresponding to two turns of the hollow body with the lacquer roller with the addition of a short overlap area.

By the pressure required in the contact zone between the cavity body and the lacquer reel, the lacquer applied by the lacquer roller is compressed, so that in the entrance gap between the areas of the cavity body and the lacquer roller approaching, a lacquer alignment or lacquer structure is maintained which is maintained throughout the contact time. the hollow body and the paint roller. In the exit gap which arises between the distant parts of the hollow body and the lacquer roller, a lacquer splitting occurs, ie. a longitudinal separation between the hollow body and the lacquer film lying on the surface of the lacquer roller, whereby no uniform tearing occurs.

35 On the contrary, at the narrowest point of the gap, first, due to the extensibility of the lacquer, a continuous bridge extending throughout the gap is formed which, with increasing gap width, becomes a number of separate single bridges which, with increasing opening width of the gap, are continuously torn and separated. as their central cross-sectional area becomes thinner. This creates unwanted lactose mist. In addition, 5 structures remain on the surfaces of the hollow body and lacquer roller of the lacquer which cannot be observed with the naked eye, and which are sometimes reduced again due to the viscosity of the lacquer, but do not disappear completely, so that only one small textured varnish on the surface of the hollow body.

The degree of varnish structure on the hollow body depends to a large extent on the viscosity of the varnish as well as on the circumferential speed of the hollow body and the lacquer roller.

To obtain the required circumferential speed of the hollow body, the rotatable mandrel of the mandrel with the then held hollow bodies is pulled only over a short portion of their path of movement towards the lacquer roller. During contact with the lacquer roller, the mandrel no longer drives, but nevertheless, the synchronized circumferential velocity of the lacquer roller and the hollow bodies is largely maintained at the pressure of the roller against the hollow bodies. The circumferential velocity of the hollow bodies and the lacquer roller at the previously known round lacquer is approx. 2 m / sec and can be increased to a maximum of 6 m / sec. At higher circumferential speeds, the varnish is atomized during the separation of the single-bridges described by the varnish described, so that a varnish mist is formed which must in any case be avoided to prevent disturbance of the lacquer. the operating function of the apparatus for performing the circumferential paintwork and also to avoid contamination of the surroundings.

Furthermore, from DE-PS No. 1,536,978 it is known for printing or varnishing of hollow bodies, e.g. tubes, driving the holding spindles accommodating the hollow bodies and the printing or varnishing mill incrementally to a desired alignment of the circumferential velocities in order to provide hollow bodies with different diameters or different thicknesses with the aid of one and the same printing mill, and thereby obtain a presumptive imprint. Hereby, it should be possible to achieve a uniform and impeccable tearing of the ink while avoiding a twist ie. distortion or distortion of the cavity especially a tube. However, this can only be achieved when the circumferential velocities of the hollow body and the printing plant are approximately equal in the area of contact. According to DE-PS No. 2121,725, the circumferential speed of the hollow body seated on the holding spindle in relation to the speed of the rotary pressure carrier arranged with this cooperating to a particular endeavor can be adjustably adjustable with a specific for the difference between the desired and the actual perimeter of the cavity corresponds to being able to execute impeccable printing of other caverns with circumferential sizes within the tolerance range, with a cliche determined for a particular perimeter of the cavern. In this way it is to be achieved that an impeccable printing can also be carried out by better tearing of the color and an undistorted image on the hollow body when the outer diameters of the hollow bodies are different.

2Q Using the initially described method of circumferential lacquering of cylindrical hollow bodies such as can blanks, the object of the invention is to provide an improved lacquer application by making the lacquer coating on the lacquer body more uniform so as to reduce lacquer consumption while maintaining of the optically recognizable coverage quality or an improvement of the coverage quality by using the same amount of varnish as hitherto, while at the same time it is desired to enable the use of high viscous varnishes with low solvent proportions also at economically sound perimeter speeds.

This is achieved by the method according to the invention, which is characterized in that the difference between the circumferential velocities is kept at least 2 and a maximum of 6 m / sec, and that during the pressure contact with the paint roller, the cavity is driven at a circumferential velocity of 10-80% higher than the the circumferential speed of the paint roller.

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The noticeably higher circumferential velocity of the cavity bodies with respect to the lacquer roller, in terms of its magnitude and effect, cannot be compared with the possible velocity differences between a pressure carrier and the cavity body for equalization between the desired and the actual circumference of the cavity.

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the body by the known method. It causes a hydrodynamic application of the lacquer film to the hollow body. The lacquer layer works. here at the same time as a lubricant and is drawn due to the higher circumferential velocity of the hollow body than by the lacquer reel into the entrance slot to such an extent that no lacquer is formed in this slot. In the separation area, the paint is no longer separated as in the case of "continuous roller coating" in that only a solution occurs between the interacting surfaces of the hollow body and the paint roller during bridging and thread forming during the varnish splitting, but because of the higher circumferential speed. of the hollow body, the lacquer film is more or less cut in the area at the radius of the hollow body. In this way, in the overlap area of the varnish application, the residual accumulation of varnish arising from the entrance gap is avoided by lifting the hollow body from the lacquer reel, and at the same time it is obtained that the structure which arises from the varnish splitting and the lacrimal tearing is not formed so that a calm and even lacquer film on the hollow body.

This means that with the same amount of varnish as in the known method, a better opacity of the varnish film is obtained on the perimeter of the cavity or a lacquer saving at the same opacity, while making the overlap area even less visible than is the case with known varnishing methods.

3Q Due to the changed conditions of the lacquer cleavage with predominant separation when cutting the lacquer film in the area at the exit gap between the hollow body and the lacquer roller, the risk of lacquer fog is also avoided at higher circumferential speeds. The torn lacquer is oriented transversely without appreciable filament formation along the surface of the hollow body, so that the lacquer gap angle, ie. the angle between the paintwork bridges,

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5 149710 which is separated in the starting slot is diminished with increasing difference between the velocities of the hollow body and the paint roller.

Due to the greater circumferential velocity of the hollow body than of the lacquer roller, circumferential laceration of the hollow body can be done over a smaller area of the lacquer roller circumference than by "straight lacquer", so that the lacquer roller co-operating with the mandrel wheel can be made shorter than in the known methods. need only move away from their circular path over a shorter distance.

Finally, it is also possible, in the method according to the invention, to use aqueous varnishes which, as is well known, have poor shooting properties and are not suitable for pressure coating with equal circumferential speeds of mandrel and varnish roller.

According to the invention, it is convenient to coat the sheets at the beginning and end of the pressure contact with the paint roller operated at a higher circumferential difference rate than in the middle contact area. In this way, a 20 thinner lacquer film is applied at the beginning and towards the end of the varnishing process than in the middle region. Since the starting and ending regions of the circumferential lacquer form the overlap zone, a substantially uniform thickness of the lacquer film is also obtained in the overlap zones, so that the thickness of the lacquer film in these zones substantially corresponds to the thickness of the lacquer film on the other part of the perimeter of the cavity body.

It has been found particularly advantageous to operate the hollow bodies at a circumferential speed of about 6 m / sec, and to operate the paint roller at a circumferential speed of approx.

At these circumferential speeds, particularly favorable results can be obtained with respect to the application of a uniform varnish layer.

In order to carry out the described method, the invention uses an apparatus with a rotary drawn paint roller and a rotating drawn mandrel whose mandrels arranged perpendicular to the wheel plane are freely rotatable about their longitudinal axes and for adaptation to their path of movement at the

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The circular trajectory of the mandrels projecting circumferential surface of the paint roller over a portion of the wheel circumference by means of guide curves is slidably displaced across their longitudinal axis of the mandrel wheel, the apparatus having an adjustable drive mechanism adapted to rotate the mandrels about their longitudinal axis. . According to the invention, the drive mechanism of the apparatus is adapted to be able to rotate the mandrels and then placed hollow bodies at a circumferential speed of at least 2 and a maximum of 6 m / sec. greater than that of the varnish roller in the region 1 q before their deflection from the circular path to align with the circumference of the varnish roller and to the onset of deflection and to again influence the mandrels towards the end of their deviation from the circular path.

An embodiment of the apparatus according to the invention, wherein the drive mechanism consists of an endless belt drive, is characterized in that the drive mechanism has a driving belt part which is guided between two guide rollers arranged in the direction of movement of the mandrel wheel and after the deflection region of the mandrel in a region before and to the beginning of their deviation from the circular path as well as in an area towards the end of their deviation from the circular path.

This mechanism may be of very simple construction and may be configured in the arrangement of the guide rollers so that after the start of the coating process the mandrels are released from the driven belt part due to their deviation of the circular path, but towards the end of the coating process again enters. the path of movement of the belt part and is thereby again included by the belt. In this way, the mandrels with the then hollow bodies at the beginning and 30 towards the end of the pressure contact with the paint roller are driven at a higher orifice differential velocity than in the middle part of the contact area.

The invention will be further explained in the following with reference to the drawing, in which: FIG. 1 schematically shows the working method of an embodiment of the apparatus for carrying out the method according to the invention.

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7 FIG. 2. schematic on a larger scale the conditions of varnish application by prior art; 3 is a view similar to FIG. 2, but showing varnish application by the method according to the invention, and 5 fig. 4 is a diagrammatic view of an overlap of a lacquer application as obtained by twice-round lacquering by the method according to the invention.

In FIG. 1 is a schematic representation of a part of a mandrel wheel 1 which cooperates with a paint roller 2. The mandrel wheel 10 can be rotated about its center axis 2 'in the direction of the arrow 3 and is provided at its perimeter with mandrels 3 which are distributed with regular spacing along the circumference of the mandrel wheel 1. The mandrels 3 are rotatably mounted in the mandrel wheel and held so that they can rotate about their longitudinal axes. Cave bodies 15 4, which are to be painted, are retained extensively on the mandrels. They are routed in known manner to the mandrels 3 and pushed into them, and after completion of the circular lacquer, they are removed again and taken for further processing.

The mandrels 3 are displaceable in the drawing not shown in the drawing in transverse direction along their longitudinal axis in the mandrel wheel 1 for adaptation to the movement path of the paint roller 2, which is rotated about its center axis 5, so that the mandrels are viewed as a whole with reference numerals. 6 designated circular path for their center axes in the region of the lacquer roller 2 is moved along a path 6a and thereby remains in pressure with the lacquer roller 2 which rotates in the direction of the arrow 7.

The mandrels 3 are driven from an endless belt pull 9, which runs in the direction indicated by an arrow 8 and is guided by 30 steering rollers 10, 11 and 12, at least one of which is simultaneously formed as a drive roller. It is seen that a belt portion of the belt pull abuts against the mandrels 3 to drive them prior to their deflection and pressure contact with the paint roller 2 and rotate them about their center axes. In the region where the 35 mandrels 3 and 3 respectively. the hollow bodies 4 located on these are in pressure contact with the lacquer roller 2, the mandrels 3 are removed by their guide along the path of movement 6a of the belt part,

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8 1497 10 is interrupted in this area, but so that before lifting the hollow body from the lacquer roller 2 'comes into contact with the belt part so that they are again driven towards the end of the pressure contact with the lacquer roller. In the example shown, the mandrels are driven 3a and 3b, respectively. again of the belt pull 9 belt part, while the mandrel 3c is out of contact with the belt part, but abuts against the circumferential surface of the paint roller 2,

The belt pull 9 brings up the mandrels 3 at a circumferential speed greater than the circumferential speed of the paint roller 10 2. The circumferential speed of the paint roller and mandrels is hereby between 2 and maximum 6 m / sec, and the perimeter speed of the mandrels 3 and 3, respectively. the hollow bodies 4 then placed during the pressure contact with the paint roller 2 are 10-80% higher than the circumferential speed of the paint roller. Hereby, 15 different conditions are obtained in the application of the lacquer roller from the lacquer roller to the hollow bodies, than is the case with "straight runs", ie at equal circumferential speeds of the hollow bodies and the lacquer roller.

The above difference is explained in more detail with reference to FIG. 2 and 3.

FIG. 2 schematically illustrates the conditions of the aforementioned continuous pressure coating. In this method, the circumferential surface of the lacquer roller 2 moves at a speed V2 in the direction of arrow 13. The hollow body 4 is also driven or included by the lacquer roller 2 at a speed in the direction of arrow 14. At the same speed, that is when V The application in the embodiment of FIG. 2 of the hollow body 4 against the lacquer roller 2, whereby a lacquer accumulation 16 is formed in the entrance slot 5, while relatively large lacquer bridges 18, 30, which with increasing separation of the surfaces of the hollow body 4 and the lacquer roller 2, are first subdivided into the gap 16 while reducing the cross-section in their center region, whereby lacquer yarns remain in the separating region until they are also torn, so as to appear on the surfaces of the hollow body 4 and of the lacquer roller, in FIG. 2 shows enlarged structure 19 and 19, respectively.

20 of the varnish application which, depending on the viscosity of the varnish, shows more or less pronounced tips, as indicated in the figure.

The separation of the varnish, that is the varnish splitting, takes place in this kind of round varnish approximately along the angular bisector line 21. The total angle is referred to as the varnish splitting angle.

In the round coating according to FIG. 3 appear completely different conditions. In comparison with the circumferential speed V2 of the hollow body 4, compared with the circumferential speed V2 of the lacquer roller 2, the lacquer structure 16 in the entrance slot, which can be seen in FIG. 2. Furthermore, in the output slot 17, due to the higher circumferential velocity of the hollow body 4, a lacquer separation or cleavage which is oriented in the direction of the hollow body 4, ie. it occurs approximately tangentially to the hollow body 15 4 or approximately in the direction of the plane 22 with a dotted line, and the salmon cleavage takes place as a kind of clipping, so that in FIG. 2 shown in FIG. 20 on the hollow body 4 and the paint roller 2 are avoided.

Lacquer application of the hollow bodies 4 at two orbits 20 and an overlap zone during the painting process leads to the described method of operation of the apparatus of FIG. 1 to a lacquer application such as that of FIG. 4.

The cavity bodies 4 are brought up to a relatively large differential velocity relative to the paint roller 2 at the beginning of their pressure contact with the lacquer roller 9 by means of the belt pull 9 25, so that only a relatively thin lacquer film is applied to the surface of the cavity bodies 4 at the beginning of the lacquer application. 4 after the beginning of the pressure contact with the lacquer roller is lifted from the belt part, the difference between their circumferential speed and the circumferential velocity of the lacquer roller is reduced, so that the thickness of the applied lacquer increases evenly until the mandrel 3 towards the end of the lacquer process is again subjected to driving action.

During the first orbit of the hollow bodies 4, as in the unfolding of FIG. 4 is denoted by D ^, the lacquer application 23 shown on an enlarged scale, which serves as a substrate

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149710 ίο 23 'for the second varnish application during the second circulation D2 · This varnish application is in fig. 4, indicated by 24. The lacquer application 24 grows in thickness until the hollow body in question is again subjected to a driving effect towards the end of the round coating. This time, respectively. this region of the circumferential surface of the hollow body 4 is unfolded in FIG. 4, indicated by the reference numeral 25. Due to the now increasing increase in the differential velocity, the thickness of the varnish application corresponding to the surface 26 is reduced until the hollow body 4 is lifted. Hereby, a varnish application as shown with the shaded surfaces of FIG.

4. It can be seen that this lacquer application has a relatively uniform thickness, and that this also applies to the ϋ designation overlap area. This uniformity is achieved by the described mode of operation of the hollow bodies 4 as well as by the way the lacquer splitting 15 as described takes place.

Of the embodiment shown in FIG. 3, it will be appreciated that this lacquer application method can easily work on the Roto-Gravure system, since the lacquer on the surface of the hollow bodies can remain lacquer due to the lacquer cleavage along the tangent 22 of FIG. 3 and the higher circumferential velocity of the hollow body 4 than the lacquer roller 2 sneaks along the surface of the hollow body and in this way covers the area between adjacent lacquer bridges. In this way, the spaces 25 between the bridges calculated by lacquer transfer by the Roto-Gravure method are deliberately uniformly covered, so that the Roto-Gravure structure after two cycles of the hollow body 4 can no longer be observed.

Since in the process according to the invention virtually no lacquer threads are drawn or the lacquer threads snuggle along and lie on the circumferential surface of the hollow body 2, it is possible without the risk of formation of lacquers to work at high circumferential speeds up to 6 m / sec. , whereby water-based varnishes can also be used.

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Claims (4)

149710 o PATENT REQUIREMENT. A method of lacquering the circumference of cylindrical hollow bodies (4), such as can blanks, wherein the hollow bodies are kept rotating about their longitudinal axes rotatable mandrels (3) on a drawn mandrel wheel (1) and pressed against a drawn, mandrel wheel axis parallel, lacquer roller (2) in a lacquer mill and in the contact area with the lacquer roller together with the mandrels are guided along the contour of the roller, and where the hollow bodies (4) and the lacquer roller (2) are driven separately at different 10 revolutions, characterized in that the difference between the rotational speeds is kept at least 2 and a maximum of 6 m / sec, and that during the pressure contact with the paint roller (2), the hollow bodies (4) are operated at a circumferential speed of 10-80% higher than the circumferential speed of the paint roller (2). Method according to claim 1, characterized in that the hollow bodies (4) are driven to the middle region of the contact zone at a higher differential circumferential speed to the beginning and at the end of the pressure contact with the paint roller (2). Method according to claim 1 or 2, characterized in that the hollow bodies (4) are operated at a circumferential speed of close to 6 m / sec and that the paint roller (2) is operated at a circumferential speed of approx. 4-4.3 m / sec. Apparatus for carrying out the method according to claims 1-4 and having a rotating drawn paint roller (2) and a rotating drawn mandrel wheel (1), the perpendicular (3) arranged perpendicular to the wheel plane about their longitudinal axes and for adjusting their movement path to the surface of the paint roller (6) projecting in the circular path (6) of the paint roller (2) over part of the wheel circumference by means of control curves is slidably mounted in the mandrel wheel (1) in a direction across their longitudinal axes, the apparatus having an adjustable drive mechanism which arranged to rotate the mandrels (3) about their longitudinal axis, characterized in that the drive mechanism is adapted to rotate