EP0260178A1 - Printing machine for printing on convex surfaces - Google Patents

Abstract

Printing machine for oval objects. According to the invention, the object is subjected to a simple pivoting around an axis (O) distinct from the center (O ') of the radius of curvature of a section (AA') of the zone to be screen-printed while the screen printing screen, integral with a support of a printing means or a screen (25) is movable to simultaneously correct the distance between said screen and the axis of rotation of the object. Application to the decoration processes of convex surfaces by screen printing, hot press, dry OFFSET ...

Description

The invention relates to a printing machine for printing on a convex surface, in particular on three-dimensional objects; it relates more particularly to a new arrangement allowing screen printing on cylindrical objects with non-circular convex section.

A screen printing machine comprises a frame inside which the screen screen is stretched and an inking spatula or squeegee moving on the surface of the screen to apply the ink, through the meshes of said screen. , on an object in contact with the other face of the screen.

If the surface of the object is not flat, it is necessary to cause a relative movement between the latter and the screen, so that the area to be screen printed rolls without sliding on the surface of the screen.

If, for example, the object to be screen-printed is cylindrical with a circular section, the mechanism is relatively simple and in particular, the movement to which said object is subjected is reduced to a simple rotation around the axis of the zone to be screen-printed.

On the other hand, if, while being cylindrical, the object to be screen printed has any convex section, commonly called oval, the mechanism is more complex since the rotation of the object is then accompanied by a displacement of the latter by report to the screen plan.

The known mechanical solutions to this problem are therefore complicated and relatively expensive.

In particular, in an automatic machine of this type, the conveying means which present an object facing the screen, are notably complicated by the fact that the position of the support of the object varies.

The invention aims to provide a simpler and less expensive mechanism for printing on a convex surface.

The basic idea of the invention consists in simplifying the movement to which the object is subjected by making the distance between, on the one hand, the screen printing screen, or more generally the plane printing means concerned in the in the case of the implementation of another printing process, and, on the other hand, the axis of rotation of the object.

More specifically, the subject of the invention is a printing machine for printing on at least one substantially cylindrical convex area of the surface of a three-dimensional object, of the type comprising a movable assembly capable of carrying a planar printing means , for example a screen printing screen, and means for pivoting said object so that said zone remains substantially in the plane of said printing means, characterized in that it comprises means for pivoting said object on itself around an axis of fixed position, that is to say around an axis of rotation whose position is fixed relative to the frame, and means for simultaneously correcting the distance between said printing means and the axis of rotation of said object and such that said printing means remains parallel, to itself.

According to a first possible embodiment, the means for correcting the distance between the printing means and the axis of rotation of the object result from the fact that, in the manner of a deformable parallelogram, the mobile assembly carrying this printing means is mounted articulated between two mechanisms forming rods, of equal length, pivoting around trees, in practice horizontal, respective.

According to a second possible embodiment, the mobile assembly is mounted movable perpendicular to the plane of the printing means, and, by an upright itself mounted movable parallel to this plane, it is articulated to a crank locked in rotation on the means suitable for rotating about an axis of rotation fixes the object to be printed.

In either case, and in addition to displacement longitudinal necessary for printing, the screen or other printing means used is, jointly, the object, because of the mobile assembly which carries it, of a displacement which, transverse with respect to the previous one, the gradually approaches the axis of rotation of the object being printed, then moves it away, which ensures the desired distance correction between this printing means and this object.

However, and this is an important characteristic of the invention, the axis around which the object rotates during its printing is advantageously fixed relative to the frame.

This results in an advantageous simplification of construction, and, in particular, an advantageous simplification of the conveying means necessary for automatically bringing, one after the other, to the printing station, the objects to be printed.

In addition, and in particular in the case of screen printing, the printing machine according to the invention advantageously easily lends itself to adaptation to the printing of cylindrical objects of convex section with different radii of curvature, as well than that of cylindrical objects of circular section or that of flat objects.

In fact, according to an additional characteristic of the invention, the mobile assembly used comprises a guide on which the support of the printing means is slidably mounted, the means for rotating the object to be printed on itself include holding elements for this object mounted to rotate about an axis parallel to the cylindrical zone to be printed on this object, and said printing medium support is subject to follow the direction of a pivoting element having a curvature and a pivot axis representative of the curvature and of the pivot axis of said cylindrical area to be printed on said object.

It suffices, therefore, for each object to be printed, whether it is a cylindrical object of non-circular convex section or whether it is a cylindrical object of circular section, choose the pivoting element to be used accordingly, in practice a pinion or fragment of pinion, and to corollary to the necessary adjustments.

• - la figure 1 est une vue schématique en élévation d'une machine d'impression sérigraphique conforme à l'invention ;
• - la figure 2 est une vue de détail, et à plus grande échelle, en élévation, de l'un des mécanismes formant biellettes que comporte cette machine d'impression ;
• - la figure 3 est une vue de dessus en coupe partielle de la figure 2 ;
• - les figures 4 à 6 sont des vues schématiques, qui, analogues à celle de la figure 1, illustrent le fonctionnement de la machine d'impression concernée ; et
• - les figures 7 à 9 sont des vues schématiques, qui, analogues, chacune respectivement, à celles des figures 4 à 6, se rapportent à une autre forme de réalisation.

The invention will be better understood, and other advantages will appear more clearly from it, in the light of the description which follows, by way of example, with reference to the appended drawings in which:

• - Figure 1 is a schematic elevational view of a screen printing machine according to the invention;
• - Figure 2 is a detail view, and on a larger scale, in elevation, of one of the link forming mechanisms that this printing machine comprises;
• - Figure 3 is a top view in partial section of Figure 2;
• - Figures 4 to 6 are schematic views, which, similar to that of Figure 1, illustrate the operation of the printing machine concerned; and
• - Figures 7 to 9 are schematic views, which, analogously, each respectively, to those of Figures 4 to 6, relate to another embodiment.

In the embodiment shown in Figures 1 to 6, the screen printing machine 11 according to the invention comprises a movable assembly 12 mounted articulated between two mechanisms forming rods 13, themselves pivoting relative to the frame 14 of the machine . This mobile assembly 12 includes a kind of support frame composed of two sliding shafts 16, parallel, and here horizontal, and two uprights 18, here vertical, forming lockable slides.

The uprights 18 are supported by yokes 19 themselves articulated to the mechanisms forming connecting rods 13, respectively. However, the position of the yokes 19 along the uprights 18 can be adjusted. More specifically, a system screw-nut, controlled by a crank 22, makes the connection between each upright 18 and the corresponding yoke 19, the latter carrying the corresponding nut. The screw-nut system is controlled at the upper part of each upright 18 by a crank 22 located in the extension of the corresponding screw. The two screw-nut systems of the two parallel uprights 18 are coupled by a chain link, not shown.

The two shafts 16 carry a squeegee support 24 and a screen support 25. The squeegee and the screen printing screen fixed to the supports 24 and 25 are conventional sub-assemblies and have not been shown so as not to overload the drawings.

In the envisaged application, consisting of screen printing cylindrical "oval" surfaces, the squeegee support 24 is fixed to the shafts 16 while the screen support 25 is capable of sliding along them; these trees therefore form a guide for the screen support 25.

In the embodiment shown, the screen support 25 is generally U-shaped and comprises two vertical uprights 28 provided with rings 29 sliding on the shafts 16 and a lower horizontal crosspiece 30 carrying a rack 31. Thus, when, as indicated, the squeegee support 24 is immobilized along the shafts 16, the screen support 25 can move along the same shafts 16 by a certain amplitude, on either side of said squeegee support.

Each link forming mechanism 13 is of adjustable useful length and comprises two parallel rods 35,36, rigidly secured to one another by two end spacers 37. A first rod 35 is clamped in a first articulation part 38 integral with a shaft 39, here horizontal, itself mounted rotating in yokes 40 fixed to the frame 14. Bearings 40 a are interposed between the yokes 40 and the shaft 39. The assembly of the two rods 35,36 is oriented with respect to the shaft 39 so that the second rod 36 intersects the geometric axis (P1) of said shaft 39, perpendicular to it (see Figures 1 and 2). The lower end of said second rod 36 is integral with a second articulation part 43 (FIG. 3) fixed to the mobile assembly 12 by means of the corresponding yoke 19. More specifically, said yoke 19 is articulated to a horizontal pin 41 (of axis P2) itself linked to the second rod 36. It is therefore understandable that when the two mechanisms 18 forming rods are adjusted so that their useful length (i.e. the distance P1, P2 between the geometric axes of the shaft 39 and the journal 41) is the same, the movable assembly 12 to which are fixed both the screen printing screen and the squeegee , is capable of carrying out a controlled pendulum movement, while remaining parallel to itself. As will be seen below, the suitable useful length P1, P2 depends on the object to be screen printed. The pendulum movement is transmitted by a chain 42 in engagement, in particular with two pinions 44 respectively integral with the two shafts 39. The chain 42 is driven from a motor or a jack, by any suitable means (for example by through a cam) capable of imparting to it a back-and-forth movement of desired amplitude.

Referring more particularly to FIG. 3, it can be seen that the first rod 35 of a link-forming mechanism 13 is fixed perpendicular to the shaft 39 and laterally with respect thereto, by elastic clamping by means of a part. elastically deformable 45, forming a yoke. The shaft 39 also comprises two coaxial parts 39 a , 39 b , respectively internal and external. The pinion 44 is integral with the external part 39 b in the form of a sleeve, which carries at one of its ends, a pinion 46 in engagement with a rack 35 a cut along said first rod 35. The internal part 39 a is fixed to an axial stop 49 in contact with the part 45 forming a yoke and capable of tightening it while coming to bear against the adjacent end of the second part 39 b of the shaft 39. To do this, the rear end Of the game internal 39 a is threaded and receives a nut 50 bearing on the other end of the external part 39 b . In this way, when the nut 50 is tightened, the two coaxial parts 39 a , 39 b and the rod 35 are made rigidly secured, so that the assembly constituted by the rods 35 and 36 can be subjected to a movement of pendulum, when the chain 42, engaged with the pinion 44, is moved back and forth. On the other hand, if the nut 50 is temporarily loosened, a movement transmitted by the chain 42 results in a rotation of the pinion 46 controlling the sliding of the rod 35 in the part 45 forming a yoke, which is loosened. Thus, the useful length of the link mechanism 13 is adjusted. As the chain 42 is engaged with the two pinions 44 of the two mechanisms 13, the length adjustment is made simultaneously on both sides.

On the other hand, the machine includes means for pivoting the object on itself around a chosen axis of this object. A part of these means is visible in FIG. 1. It is a horizontal shaft 60 mounted rotating in a fixed structure 61 of the frame 14 and bearing in base 63 shaped to receive one end of the object. The latter (not shown) can be held horizontally in the extension of this base by means of a tailstock or similar equipment (not shown), for example cooperating with a neck if the object is a bottle and if the position of this neck lends itself to this method of attachment; if this is not the case, another base is provided, shaped according to the object, placed opposite the base 63 and mounted rotating around another horizontal shaft, located in the axial extension of the shaft 60 , so that the object can rotate on itself around a fictitious axis crossing it, here a horizontal axis.

For convenience, it will be assumed that, in the example described, the convex cylindrical zone to be screen printed of said object has a constant section, perpendicular to the aforementioned fictitious axis and that this section is comparable to an arc of circle AʹA also represented by an edge of the base 63.

It will be appreciated that, according to the invention, the only movement communicated to the object is a rotational movement on itself, which greatly simplifies the mechanisms for positioning and maintaining the objects to be screen printed.

However, as the object is not a cylindrical object with circular section, its own axis of rotation O, is not confused with the axis Oʹ of the cylindrical area AAʹ to be screen printed. The axes O and Oʹ appear by points in FIG. 1. In practice, the axis O is chosen to cut, in the plane of the figure, the radius of curvature OʹB passing through the center O of the corresponding arc AʹA.

If the shape of the object presents a singularity facilitating its maintenance, the axis O is chosen according to this singularity. Thus, if the object is, for example, a bottle comprising a neck placed in the extension of an axis of symmetry of the object, the axis O will preferably be merged with this axis of symmetry.

Furthermore, the screen support 25 is subject to follow the contour of a pivoting element having a curvature and a pivot axis representative of the curvature and of the pivot axis of the aforementioned convex cylindrical zone, shown in the drawings. by the arc AʹA.

In the embodiments shown, this pivoting element is a fragment of pinion 62 (or a complete pinion) mounted pivoting eccentrically at the end of a horizontal shaft 60 a , parallel to the shaft 60.

This pinion fragment 62 is in engagement with the rack 31.

As indicated above, its curvature and its dimensions are representative of the object to be printed, and more particularly of the characteristics of the surface concerned, represented here by the arc AʹA thereof. It is therefore interchangeable depending on the shape and dimensions of this object. Thus, in the embodiments shown, the average radius of curvature R of the teeth of the pinion fragment 62 is equal to the radius of OʹB curvature, the distance from the center of rotation of this pinion fragment 62 (the axis of the shaft 60 a ) to its teeth is equal to the distance OB, etc.

The drive chain 42 connecting the two pinions 44 of the shafts 39 passes around a pinion 64 secured to the shaft 60 a . The shafts 60 and 60 a are coupled in rotation in the same direction, by a gearbox of ratio 1, not shown. Of course, the trees 60 and 60 a could be confused.

In operation, the useful length P1, P2 of the link rod mechanisms 13 is adjusted to be substantially equal to the radius of curvature OʹB of the zone to be screen printed, that is to say also to the radius of curvature R of the pinion fragment 62. Once this adjustment has been made, action is taken on the screw-nut systems of the uprights 18 to bring the rack 31 into engagement with the pinion fragment 62. The operation follows with obviousness from the preceding description and appears clearly in FIGS. 4 to 6 .

At the start of the screen printing operation (FIG. 4) the pivoting mobile assembly 12 carrying both the squeegee support 24 and the screen support 25 is tilted to the right (considering the drawings) while the fragment of pinion 62 is inclined as far as possible to the left while remaining in engagement with the rack 31. The screen printing is carried out by a pendulum movement from right to left of the assembly 12 until, first of all, an intermediate position ( Figure 5) where the link rod mechanisms 13 are vertical. It can be seen that the pinion fragment 62 has pivoted clockwise and that the screen support 25 has lowered at the same time as, by sliding on the shafts 16, it has moved towards the straight with respect to the squeegee support 24, which is fixed on them. The movement continues (FIG. 6) until the assembly 12 completes its pendulum movement from right to left and the pinion fragment 62 completes its pivoting in the clockwise direction. During this second part of the movement of balance, the screen support 25 continues to move to the right relative to the squeegee support 24, but, instead of lowering, as before, it is raised.

During all these operating phases, the object executed the same movement as the fragment of pinion 62 while rolling without sliding on the lower face of the screen while a relative movement between said screen and the squeegee occurred on the upper surface. of the screen, above said object.

The machine which has just been described can be used for printing a cylindrical object with circular section. In this case, it suffices to block the mechanisms forming link rods 13 in the position in FIG. 5 and to use a pinion fragment 62 rotating around its geometric axis and with the same radius of curvature as the object.

For printing flat objects, the screen support 25 can be left stationary and the squeegee support 24 released so as to impart a translational movement to it relative to the screen support 25.

In the embodiment illustrated in FIGS. 7 to 9, in which the same elements have been designated by the same references, the movable assembly 12ʹ which the printing machine according to the invention comprises is mounted movable perpendicular to the plane of the screen printing screen or other printing means used, and, by an upright 75, itself mounted movable perpendicular to this plane, it is articulated to a crank 77 locked in rotation on the means suitable for pivoting around 'a fixed axis of rotation or pivoting O the object to be printed.

As before, this mobile assembly 12ʹ includes a guide 16 on which the corresponding screen support 25 is slidably mounted.

As before, also, this guide 16 can be formed by two parallel shafts of which only one is visible in the figures.

In the embodiment shown, this guide 16 further comprises, parallel to one another, and connecting one to the other the preceding trees when such trees are used, two cross members 71, which each form a bushing, and by which it is slidably engaged on two balusters 72 perpendicular to the plane of the printing means and secured to the frame 14 of the machine.

These columns 72 are therefore here vertical.

Anyway, the upright 75 on which this movable assembly 12 ensemble is articulated to the crank 77 is also slidably mounted, by a sleeve 76, on the guide 16.

The crank 77, which has only been shown schematically in broken lines in the figures, its production falling within the skill of the art, is in practice locked in rotation on the shaft 60, which, mounted rotating in a fixed structure of the frame 14, carries a base shaped to receive one end of the object to be printed.

At its other end, there is provided, between it and the upright 75, a roller 78 suitable for their mutual articulation in Oʹ.

Preferably, this roller 78 is adjustable in position, for adjusting the distance OOʹ as a function of the radius of curvature of the area to be printed of the object concerned.

For example, the roller 78 is carried adjustable in position by a buttonhole mounting on any of the elements that constitute the upright 75 and the crank 77, and it is engaged with a groove provided for this purpose on the other of these elements.

The squeegee support associated with the screen support 25 can, moreover, be fixed relative to the upright 75.

The operation of this second embodiment is similar to the previous one: when, pivoting on itself, for example clockwise, the object to be printed rotates around the fixed axis O, along the arrow F1 of FIG. 7, and that, jointly, the pinion fragment 62 which is in its image, centered on the axis Oʹ, and carried by a shaft 60 a , pivots in the same direction, meshing with the rack 31 carried by the lower cross member 30 of the screen support 25, which causes a sliding from left to right of this screen support 25 on the guide 16, along arrow F2, and, jointly, a sliding, in opposite direction, of the upright 75 on this same guide 16, there is, first of all, in FIG. 7, a progressive lowering of the mobile assembly 12ʹ, before, after passing to a low neutral point, in FIG. 8, it is raised, FIG. 9.

As before, there is thus, simultaneously with the movement of the screen in contact with the print area of the object, a systematic correction of the distance D between this screen and the axis of rotation O of this object.

For convenience, this distance D has been identified between the axis O and the rack 31 in Figures 7 to 9; it goes through a minimum value for the neutral position of figure 8.

It will be appreciated that, with this embodiment, the adjustments to be made advantageously only intervene at one point, in this case the roller 78.

Of course, if, as previously, for the sake of simplicity, the shaft 60 a carrying the pinion fragment 62 has been assumed to coincide, in the figures, with the shaft 60 carrying the object to be printed, it may be in reality distinct and parallel trees.

The mechanisms which have just been described do not apply only to the implementation of a screen printing. Their adaptation to other printing processes using a planar printing means such as a heating plate for a gilding press, of the kind described for example in French patent No. 2314831, or a blanket and plan set for dry OFFSET machine, etc., is on the contrary possible and obviously falls within the scope of the invention.

Claims (10)

1. Printing machine, for printing on at least one substantially cylindrical convex area (AAʹ) of the surface of a three-dimensional object, of the type comprising a movable assembly (12,12ʹ) capable of carrying a printing means plane, for example a screen printing screen, and means for pivoting said object so that said zone (AAʹ) remains substantially in the plane of said printing means, characterized in that it comprises means (60) for making rotate said object about itself around a fixed position axis and means (13,16-72) for simultaneously correcting the distance between said printing means and the axis of rotation of said object and such that said means impression remains parallel to itself. 2. Printing machine according to claim 1, characterized in that said mobile assembly (12) is mounted articulated between two mechanisms forming connecting rods (13) of equal length, pivoting around respective parallel shafts (39). 3. Printing machine according to claim 1, characterized in that the mobile assembly (12ʹ) is mounted movable perpendicular to the plane of the printing means, and, by an amount (75) itself mounted movable parallel to this plane, it is articulated to a crank (77) locked in rotation on means (60) suitable for pivoting about an axis of rotation fixes the object to be printed. 4. Printing machine according to any one of claims 1 to 3, characterized in that the movable assembly (12,12ʹ) comprises a guide (16) on which is slidably mounted a support for printing means or d 'screen (25), the means for pivoting the object on itself comprise holding elements (63) of this object mounted to rotate about an axis (O) parallel to the convex cylindrical zone (AAʹ) of said object, and in that said printing means or screen support (25) is subject to follow the contour of a pivoting element (62) having a curvature and a pivot axis representative of the curvature and of the pivot axis of said convex cylindrical zone (AAʹ) of said object. 5. Printing machine according to claim 4, characterized in that said printing or screen means support (25) comprises a rack (31) and that said pivoting element (62) is a pinion or fragment of pinion (62) mounted eccentrically pivoted, whose curvature and eccentric pivot axis correspond to the curvature and the pivot axis of the convex cylindrical area (AAʹ) of the object. 6. Printing machine according to claims 2 and 5, taken together, characterized in that the useful length (P1, P2) of the link mechanisms (13) is substantially equal to that of the radius of curvature (R) of the pinion or pinion fragment (62). 7. Printing machine according to claim 6, characterized in that the link rod mechanisms (13) are of adjustable length to adapt to different radii of curvature of said pinion or pinion fragment (62). 8. Printing machine according to claim 7, characterized in that each link-forming mechanism (13) comprises two parallel rods (35,36) rigidly secured to one another by two end spacers (37), in that a first rod is clamped in a first articulation part (38) rotatably mounted at the end of the corresponding shaft (39), in that the assembly of the two rods is oriented so that the second rod (36) intersects the geometric axis (P1) of said shaft (39), perpendicular to it, and in that one end of this second rod is integral with a second articulation part (43) fixed to the mobile assembly (12) concerned. 9. Printing machine according to claims 3 and 4, taken together, characterized in that the amount (75) by which the movable assembly (12ʹ) is articulated to a crank (77) is also slidably mounted on the guide (16). 10. Printing machine according to any one of claims 1 to 9, characterized in that, as regards screen printing, the mobile assembly (12, 12ʹ) also comprises, associated with the support of printing means or screen (25), a squeegee support (24).

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