EP0081443A1 - Preadjusting method for a dry offset machine - Google Patents

Abstract

Method for presetting a dry offset machine, intended for printing cylindrical or conical parts, according to which presetting templates are produced from a matrix film, also used as the basis for the production of working plates , and are used to permanently adjust the machine so that the subsequent introduction of the shots only gives rise to a simple check.

Description

The present invention relates to a method for presetting a dry offset machine intended for printing cylindrical or conical parts. Many products are presented in cylindrical or conical containers, so for example in the field of cosmetics, aerosol tubes and jars are used. Glue tubes, yogurt jars and spray paints are other examples. The decoration or the indications which appear on these containers are printed by means of dry offset machines. These machines are quite expensive, so it is advisable to use them almost continuously to amortize them. This is even more imperative when the printing is carried out by a machine integrated into a complete manufacturing line in which the parts are shaped, printed, dried, undergo a final machining and are even sometimes filled and packaged. In such production lines, any downtime represents a considerable loss. However, it is necessary to stop the line when changing the shots to start a new series of pieces with different patterns. Given the cost of immobilizing the machine, the time spent setting up and adjusting a new set of plates should be kept to a minimum. This concern is also found in other areas where printing intervenes and has given rise to numerous attempts. There are thus various solutions which are exposed in particular in patent documents. Most of these solutions obey the same principle: combine the operation of fixing or hanging the plate on the plate holder sector with the operation of adjusting the plates between them. The application of this principle generally results in the arrangement in the plate of perforations in which hooking claws integral with the sector are housed and then tend and place the plate on the sector. Various variants of this kind of solution are set out in particular in the documents: CH 492 557, CH 551 241, DE Offenlegungsschrift 25 01 266, DE Offenlegungsschrift 29 44 675, DE Offenlegungsschrift 30 25 060, DE Auslegeschrift 20 45 953, DE Patentschrift 20 10 899, GB 1,575,016, US 3,908,546.

The main characteristic of the already known solutions is that the precision of the machine adjustment is dependent on the precision with which the perforations have been made as well as the exact adjustment of the claws in the shape of the perforations. This precision is limited by the necessary characteristics of the material used to make the plates, as well as by the difficulty of producing claws which are both mobile and which however have no play. In practice, these systems are not used because they do not not give full satisfaction. The adjustment of the machine shots is therefore carried out most of the time by trial and error, the duration of the operation then depending on the skill or the luck of the operator of the machine. For a four-color machine therefore having four sectors on which four plates are mounted, the setting time is approximately two hours. It is with the intention of reducing this adjustment time to approximately fifteen minutes that the present invention was made.

The solution defined by the invention is set out in the claims.

• la fig. 1 montre un gabarit de préréglage
• la fig. 2 montre le maître-gabarit
• la fig. 3 montre une vue d'un secteur porte-blanchet et d'une pièce-épreuve.
• la fig. 4 montre une vue du marquage d'un secteur
• la fig. 4b montre une vue du guide de marquage
• la fig. 5 montre une vue d'un secteur sur lequel des axes sont tracés
• la fig. 6 montre une vue d'un cliché de travail (ou d'un gabarit) lors de la mise en position sur un secteur.
• la fig. 6 e montre l'apparition par une perforation de l'axe tracé sur un secteur
• la fig. 7 montre une variante enrichie du maître-gabarit et
• la fig. 8 montre une variante enrichie d'un gabarit

The process is described below by the text and the drawing where:

• fig. 1 shows a preset template
• fig. 2 shows the master template
• fig. 3 shows a view of a blanket sector and a proof room.
• fig. 4 shows a view of the marking of a sector
• fig. 4b shows a view of the marking guide
• fig. 5 shows a view of a sector on which axes are drawn
• fig. 6 shows a view of a working shot (or a template) when positioning in a sector.
• fig. 6 e shows the appearance by a perforation of the axis traced on a sector
• fig. 7 shows an enriched variant of the master template and
• fig. 8 shows a variant enriched with a template

Fig. 3 does not show the image printed on the blanket as it actually appears, in fact, the templates being engraved in positive, they are "readable", which has the consequence that the blanket is "illegible" since the image is reversed. In the drawing, this inversion has been deliberately ignored so that the reader finds the various elements in the same arrangement in all the figures.

As seen in fig. 1, the preset template is a thin plate, identical to those usually used in dry offset. The template 1 is produced according to the same process as a working plate. The various elements that appear on the template in the figures are first arranged on a lithorthochromatic film allowing copying on photopolymer plates, the plates then being immersed in a washing bath creating the relief.

In the following description, the various engraved elements participating in the invention are described as they appear on the photograph produced. The operations which make it possible to re-make the film, and then to etch the plates are a technique well known to those skilled in the art and are not described here.

Usual locating crosses 2 in photoengraving are placed on a film. Two axes AA 'and BB' are added. The axis AA 'is arranged parallel to the axis of rotation of the plate-holding sector on which the template will be fixed in a subsequent step. The axis AA 'is located near the right hooking margin 3 of the template. Its position more or less close to said margin does not play a role. The second axis BB 'is then arranged perpendicular to the axis AA' in the variant presented. The direction of the axis BB 'is however not necessarily perpendicular to the axis AA', but it is preferable that the two axes form an angle between 80 and 100 ° between them. The film carrying the locating crosses 2 and the axes AA 'and BB' constitutes a basic matrix. On a copy of this matrix, we then have (fig. 2) four alignment bars 8,. 9, 10 and 11 strictly parallel to the axis AA ', therefore to the axis of rotation of the plate-holder sector. These bars have a width of 5 mm and a length of 35 mm in the variant shown. The two right bars 9 and 11 are placed at a distance from the right edge 12 of the plate which varies according to the machine on which the plates will have to work. For a machine of the W1FAG type, the distance which separates the right edge 12 of the plate from the right edge 13 of the bars 9 and 11 is fixed at 40 mm. The top 14 of the bar 9 is placed 25 mm from the top of the plate 15. The base 16 of the bar 11 is located 25 mm from the bottom of the plate 17. The two left bars 8 and 10 have the same dimensions as the two bars on the right. Their positioning on the photograph takes into account two factors. First rement, their position is determined by two perpendicular to the axis AA '. One of them is raised by the vertex 14 of the upper right bar 9. The vertex 18 of the bar 8 is aligned on this perpendicular. In the same way, the base 16 of the bar 11 and the base 19 of the bar 10 are aligned on the same perpendicular to the axis AA '. Secondly, the distance which separates the right side 13 of the two right bars 9 and 11 from the left side 20 of the two left bars 8 and 10 is determined by the development of the parts on which the printing will finally take place. The usual diameters of the parts which are printed by means of plates of the format shown are 35, 40 and 45 mm. The developments of these parts are therefore respectively 109.2 mm, 124.8 mm and 140.4 mm. In the variant shown in FIG. 2, the distance is 124.8 mm and thus corresponds to a part 40 mm in diameter. It is also envisaged to include on the same template the bars corresponding to several developments (fig. 7). The number of templates that must be engraved depends on the number of color groups in the machine. For a dry offset press with four color groups, four templates are produced. The first of these four templates, the master template-100 which corresponds to the first sector, includes all the elements described so far, namely the crossbeams 2, the positioning axes AA 'and BB' and the bars alignment 8, 9, 10 and 11 (fig. 2). The other three templates are identical to each other, but only have crosses 2 and axes AA 'and BB' (fig. 1). Once the four templates have been made, four perforations are made on each of them. The four perforations are positioned in the same way and in the same places on each template. We practice, centered on the axis AA ', two perforations 4 and with a diameter of the order of 5 to 10 mm, one of the perforations 4 made in the top of the plate, the other 6 in the bottom. These perforations are circular in the drawing, but other shapes are also envisaged, in particular oblong, square or triangular. Two other perforations are then made on the axis BB ', one 5 on the right of the template and centered both on the axis BB' and on the axis AA '. This perforation is also provided away from the axis AA ′, but the variant shown in FIGS. 1 and 2 makes it possible subsequently to have a third reference 5 which is added to the two perforations 4 and 6 of the axis AA 'already described. A second perforation 7 is made on the axis BB ', but on the left of the template this time. The four templates are then bent to a curvature barely more open than that of the sectors on which the templates will be mounted. Once the templates are perforated and bent, they are machine mounted. Machine presetting can then be carried out. The presetting begins with the positioning of the master template on the first color group of the machine. The master jig 100 is the one which has the alignment bars 8, 9, 10 and 11 in addition to the crosses 2 and the axes AA 'and BB'. The master template is fixed on the sector corresponding to the first group. A test piece 21 is then placed on the workpiece mandrel 22 (fig. 3). After inking the template, a pass is made with the blanket 23. The ink is transferred from the template to the blanket 23 then, from the latter, to the test piece 21. At this stage, the end of the blanket 23 doesn’t is not yet adjusted and an additional part 24 protrudes. As a result, the blanket 23 is in contact with the test piece 21 over a developed length greater than the development of the piece. As a result, the ink that the blanker 23 has deposited on the proof piece 21 is redeposited, after the piece has made a complete revolution, on the additional part of the blanket.

As shown in fig. 3, the first patterns deposited by the blanket are the bars 8 and 20, these are printed 8 'and 10' on the piece 21 then redeposited on the blanket 8 "and 10". It is then checked that the top 18 "of the bar 8" is aligned at the same height as the top 14 of the bar 9 which marks the end of the blanket. We also check the alignment of the base 19 "of the bar 10" with the base 16 of the bar 11. If the vertices 18 "and 14 and the bases 19" and 16 are not aligned, we adjust the master template 100 on the sector by the set of fixing bars 34 (fig. 6) until said alignment is obtained. When the alignment is obtained, we have the demonstration that the axis AA 'as well as the alignment bars 8, 9, 10 and 11 are well oriented parallel to the axis of rotation of the sector.

The space which separates the bars 14 and 18 "as well as the bars 16 and 19" comes from the fact that the number_ τ has a conventionally different value in this area of printing, the conventional value is: 3.12.

Depending on whether the offset machine rotates clockwise of a watch (Type WIFAG) (fig. 3) or in the opposite direction, the end of the blanket will be on the right or on the left, in this case, all the positions of the above elements are simply reversed.

The master template 100 being correctly positioned on the first sector, the sector is marked (fig. 4) by means of a stylus by tracing two marks aligned on the axis AA 'by the perforations 4 and 6 and two others marks aligned on the axis BB 'by the perforations 5 and 7.

To mark, use either a simple stylus 25 (fig. 4) or a stylus mounted on a guide 26 (fig. 4a). In the latter case, the guide has a countersink 27 which follows the relief of the axis 28 and drives the stylus by sliding on the rail formed by the relief of the axis.

To adjust the group corresponding to the second color, one of the three identical templates shown in fig. 1. We then pass over the blanket, but without using a proof piece this time. The master template 100 which is mounted on the first sector deposits its patterns, in particular the locating crosses 2 on the blanket as in FIG. 3. The second template 1 in turn deposits its patterns, as shown in FIG. 1 on the blanket. The second template is then adjusted on the second sector until its locating crosses 2 exactly coincide on the blanket with the crosses 2 left by the master template 100. When the coincidence of the crosses is perfect, the marking of the second is practiced sector in the same way as for the first.

The operation described above is repeated for the third, then for the fourth sector. The cross marks corresponding to the four groups are thus perfectly superimposed and the four sectors are marked.

We then remove the four templates from the machine and trace (fig. 5) on each of the sectors the axes AA 'and BB' by connecting the marks which have been marked through the perforations 4, 5, 6 and 7 as described above. Each of the sectors therefore carries the two axes AA 'and BB' as shown in FIG. 5.

In an enriched variant (FIGS. 7 and 8), the templates receive, in addition to the elements already described, gauges 29 making it possible to control the pressure on the blanket as well as the lining and millimeter scales 30, 31 and 32. The gauges 29 are arranged differently on each of the four templates so that the gauges on each template leave a distinct imprint on the blanket.

The millimeter scales each have their own function. Ladders 30 and 31 are arranged on the master template (fig. 7). The origin of the scale 30 is placed on the blanket end line which is determined by the straight edge 13 of the alignment bars 9 and 11. As mentioned above, the blanket is longer than the development of the proof piece. The scale 30 is printed from the master template on the additional part 24 of the blanket (fig. 3). Reading the reported scale 30 gives the exact indication of the length of the additional part 24 which will have to be deleted. This indication makes it possible to adjust the blanket holder sector 33 so that the real end X of the blanket coincides with the ideal end Y determined by the straight edge 13 of the alignment bars 9 and 11. The second millimeter scale 31 (fig. 7) is placed perpendicular to the axis AA '. Its origin is placed in the central part of the master template, the exact position does not play a role. However, when it has been chosen, it will be transferred exactly to the other three templates 1 (fig. 8). The scale 31 is double in the sense that the graduation develops to the right and to the left from the origin.

On the other three templates 1, a millimeter scale 32 is arranged (fig. 8). Its center is the deferred origin of the scale 31; its axis is parallel to the axis AA '.

The ladder 31 is deployed over the entire length of the master jig, since it frequently happens that the sectors of a machine are in a completely de-synchronized phase. In this case, the scale 32 printed by the second template for example can be found both on the far left and on the far right of the imprint left by the master template on the blanket. The measurement of the correction to be made can be read directly at the point of intersection between the scale 31 and the scale 32. The correction in development, ie the synchronization of the sectors, can be read on scale 31; the correction affecting the height positioning of the template on the sector can be read on the scale 32. The assembly formed by the scales 31 of the master template and 32 of each of the three other templates has the same function as the locating crosses 2 , but occurs when the amplitude of the corrections is greater.

When the machine is preset, that is to say when the axes AA 'and BB' have been traced on the four sectors, the machine is ready to receive the working shots and to start the serial printing of the parts.

All working shots are made on the basis of copies of the matrix film. Therefore, the axes AA 'and BB' appear on all the pictures. They are only materialized by engraving in the vicinity of the perforations 4, 5, 6 and 7 (fig. 6 and 6e).

The setting in machine of the sets of stereotypes is summarized for the operator to check the coincidence of the axes AA 'and BB' traced on the sector with the axes AA 'and BB' engraved on the stereotype (fig. 6e). The operator just has to adjust the picture by the play of the fixing bars 34 (fig. 6) by bringing the axes in superposition.

Coincidence and control are made possible by the fact that the perforations 4, 5, 6 and 7 made on each of the photographs reveal the axes traced on the sectors (fig. 6e).

The machine preset allows different formats to be used; in fact, the axis AA 'being close to the attachment margin 3, whatever the size of the plate, it is possible to punch two holes revealing the axis AA'. Regarding the axis BB ', it will be halfway up if the picture is large, it will be at the top of the picture if it is small.

The advantage of the present invention compared to already known solutions is to be able to move the adjustment moment to a certain extent, or more exactly to split the adjustment into two separate stages. your. The first step is to preset the machine. This is a little longer than the setting as it is usually practical, but it has the merit of deploying a permanent effect, and therefore does not have to be repeated. The second step, closely dependent on the first, consists in shifting the timing of the adjustment of the plate on the sector or, more precisely, in presetting it so that the adjustment in machine is limited to a simple control, thus eliminating the groping which immobilizes the machine too much.

The systems already known also attempt to shift the timing of the adjustment, but, in addition to their uncertain functioning, they have the handicap of asking for total precision in an operation (the perforation of the pictures) which is precisely that which is least suitable for it. The present invention, on the contrary, requires the same precision of an operation which lends itself perfectly to it (copying the matrix film) whereas the perforations used are made with relative precision without any resulting disadvantage.

Claims (13)

1 / Method for presetting a dry offset machine, intended for printing on cylindrical or conical parts, composed in particular of a series of plate-holding sectors, of a blanket holder sector, of a blanket and a workpiece chuck characterized in that: a) a matrix film is produced on which two axes AA 'and BB' are engraved as well as crosses (2) b) the alignment bars (10, 11) or adjustment scales (30, 31) are engraved on a copy of the matrix film c) the templates (1) are then drawn from the matrix-a) and a master template (100) from the enriched matrix film b) d) one punctures in these templates, on the axes AA 'and BB', in the range of the plate holder sector, at two points furthest from each other on the axis AA 'and on the axis BB ', at the intersection with the axis AA' and at a point farthest from this intersection on the axis BB '. e) the master template is fixed to the first sector of the machine by adjusting its positioning using the alignment bars (8 ", 10") or the adjustment scales (30, 31) transferred to the blanket by the part - proof (21) f) adjusting and then fixing the template (1) on each of the other sectors of the machine using crosses (2) or adjustment scales (31, 32) printed on the blanket g) we identify and draw the axes AA 'and BB' on each of the sectors h) all the working shots are reproduced from copies of the matrix film while preserving on each of them the same axes AA 'and BB'. i) the working stereotypes are put in place by superimposing the axes engraved on the stereotypes on the axes traced on the sectors. 2 / A method according to claim 1, characterized in that one of the axes (AA ') is oriented so that it is parallel to the axis of rotation of the sector. 3 / A method according to claim 1, characterized in that the alignment bars (8, 9, 10 and 11) which are placed on a copy of the matrix film are divided into two groups, one (8 and 10 ) marking the beginning of the development of the part on which the printing will be carried out, the others (9 and 11) marking the end of the blanket. 4 / A method according to claim 3, characterized in that the test piece (21) transfers the images (8 'and 10') of the bars (8 and 10) on the blanket thus giving the images (8 "and 10") 5 / A method according to claim 4, characterized in that one controls the establishment of the master template (100) by checking the alignment of the bars (9 and 8 ") and bars (11 and 10") 6 / A method according to claim 3, characterized in that one has the origin of one (30) of the scales on the end of blanket line determined by the right side (13) of the alignment bars (9 and 11), this scale being transferred by the test piece (21) to the additional part (24) of the blanket. 7 / A method according to claim 1, characterized in that two perpendicular scales (31 and 32) one of which (31) is perpendicular to the axis (AA ') have a common origin chosen in the central part of the master template ( 100) 8 / A method according to claim 7, characterized in that there is on each template (1) from a simple copy of the matrix film a scale (32) having the same origin as the scale (31) of the master - template (100) 9 / A method according to claim 1, characterized in that the axes (AA 'and BB') are identified on the sectors by the opening of the perforations (4, 5, 6 and 7) 10 / A method according to claim 1, characterized in that one carries out all the working shots on the basis of the same matrix film as that which made it possible to produce the simple templates (1) 11 / A method according to claim 1, characterized in that one carries out the superposition of the axes engraved on all the working shots on those traced on the sector by bringing the axes of the stereotype in the alignment of the axes of the sector which one makes appear by the perforations (4, 5, 6 and 7) of the stereotypes. 12 / Presetting template for dry offset machine as a direct product of the process according to claim 6. 13 / Preset plate for dry offset machine as a direct product of the process according to claim 10.

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