Object decorating system

Abstract

 A silk-screen machine comprises decorating means (14, 16) in a decorating station to decorate objects (2) through a silk-screen (10) positioned therein; said decorating means (14, 16) being joined to mobile support means (15, 13, 26; 15, 13a, 26), operated by respective driving means (29) to perform a reciprocating motion comprising a step (F1) of spreading a decorating product (9) and a step (F2) of printing a surface of said objects (2) with said decorating product (9); adjusting means (18; 19, 20, 23, 27) arranged to adjust the position of said decorating means (14, 16) with respect to said objects (2); said adjusting means (18; 19, 20, 23, 27) comprising a sensitive element (19, 20, 27; 19a, 20a, 27) that is not carried by said support means (15, 13, 26; 15, 13a, 26).

Description

[0001] The invention concerns a silk-screen machine, and particularly a slide of a silk-screen machine, for decorating objects as ceramic tiles.

[0002] In the silk-screen machines, the printing pressure, that is the pressure that is applied on the screen by the printing squeegee, must be adjusted for various reasons: first of all to take into account variations in the composition of the ceramic enamel, but also in relation to variations of the temperature and of the dampness of the environment, as well as variations of the physical features of the object to be decorated.

[0003] It is, therefore, necessary to prepare a periodic setup of the machine, that involves an adjustment of the printing pressure. In the known silk-screen machines it is necessary to stop the machine to adjust the printing pressure, thus interrupting the productive cycle. The adjustment of the printing pressure is made by operating on adjustment screws, that engage a support element of the squeegees on a slide body travelling on guide means in a transversal plane with respect to an advancement line of the tiles.

[0004] When the printing pressure has been adjusted, the position of the printing squeegee with respect to the screen is kept unaltered up to the subsequent adjustment. Therefore, a problem arises of improving the known silk-screen machines, particularly to make possible a more efficient adjustment of the printing pressure.

[0005] According to the present invention, it is provided a silk-screen machine system, comprising decorating means in a decorating station to decorate, through a silk-screen, objects positioned in said station: the said decorating means being joined to mobile support means, operated by respective driving means to perform a reciprocating motion, comprising a step of spreading a decorating product and a phase of printing a surface of said objects with said decorating product; adjusting means arranged to adjust the position of the said decorating means with respect to said objects, characterised in that, the said adjusting means comprises a sensitive element that is not carried by said support means.

[0006] Thanks to the invention, it is possible to adjust the printing pressure by varying the distance between the decorating means and the objects to be decorated operating on the sensitive element in such a way as to lift up or to lower the printing squeegee, independently of the fact that the support means of said squeegee are stationary, or in movement. In fact, since the sensitive element is not in engagement with the support means, when the sensitive element is operated to adjust the printing pressure, the support means could continue to reciprocate, without the machine being stopped.

[0007] Furthermore, to have some of the adjusting means released from the support means allows the printing pressure to be varied during the printing stroke to obtain original and unusual aesthetical effects. That may be obtained by operating manually the sensitive element, or by connecting it to a suitable motorised means, that may be electronically controlled in a programmable way.

[0008] The invention will be better understood and put into practice with reference to the enclosed drawings, which illustrate an exemplifying, but not limiting, embodiment thereof, in which:

Figure 1 is a schematic section of a printing group and a positioning group for the objects to be decorated through a middle plane of a silk-screen machine, transversal with respect to the positioning group, in a step wherein a fluid decorating product is distributed on a silk screen;

Figure 2 is a section as in Figure 1, but in a step wherein the fluid decorating product is urged to pass through meshes of the silk screen

Figure 3 is a top view of Figure 1, but limited to the printing group;

Figure 4 is the deviated section IV-IV of Figure 3;

Figure 5 is a top view as in Figure 3, but in a modified embodiment of the printing group.

[0009] As illustrated in Figures 1 and 2, in a silk-screen machine 1, the products 2 to be decorated, i.e. ceramic tiles, are positioned in a printing station by means of a pair of positioning belts 3 acting on opposite sides of each tile 2, said belts being wound as a ring on respective pulleys 4 and driven each from a respective motor 5. The tiles 2 to be decorated are conveyed toward the printing station and removed therefrom, after being decorated, by means of a pair of transfer belts 6, on which the tiles 2 rest, arranged in a longitudinal direction of the printing station.

[0010] In the printing station, a plurality of longitudinal support elements 7 is provided supporting the tile 2 during decoration, while a printing group 8 distributes a fluid product 9, i.e. ceramic enamel, through meshes of a silk screen 10 defining a predetermined decorating pattern.

[0011] As illustrated in Figure 3, the printing group 8 comprises a slide 15 reciprocating on a pair of guide rods 11 extending in a transversal direction with respect to the longitudinal direction of movement of the tiles 2 on the transfer belts 6 and lying operatively in a plane substantially parallel to the tiles 2.

[0012] On the slide 15, an oscillating member 13 his hinged to oscillate around a hinge pin 12 having ends fixed to appendixes 25 of respective tubular bodies 26 of the slide 15 slidingly coupled with the guide rods 11; a first squeegee 14, spreading the enamel 9 on the meshes of the silk screen 10, and a second printing squeegee 16, capable of pressing the enamel 9 on the face of the tiles 2 facing upward, are supported in a manually adjustable manner to the oscillating member.

[0013] Both the first and the second squeegees, 14 and 16, are coupled to the oscillating member 13 by means of pairs of adjustment screws 17, which are coupled in respective threaded holes of the oscillating member and are provided with grip knobs 18.

[0014] In an intermediate position between the guide rods 11 a pressure adjusting rod 19 is interposed, which extends between the second squeegee 16 and the tile 2 being decorated. The adjusting rod 19 is equipped with a pair of cylindrical end portions 20 coupled in an angularly adjustable manner in support holes 21 machined in respective support blocks 22, through driving means 27, i.e. a knob for the manual adjustment or an electric motor, the ends of the guide rods 11 being secured to said support blocks. The end portions 20 define an axis A for angular positioning the adjusting rods 19. The middle portion of the adjusting rod 19, between the end portions 20, is preferably cylindrical with an axis B parallel to and different from the axis A defined by the end portions 20; said middle portion constituting a first cam means on which a rolling body 23 rolls, that is rotatably supported through a pin 28 on a fork 24, which is part of the oscillating member 13.

[0015] The slide 15 is caused to reciprocate along the guide rods 11 by driving means comprising a connecting rod 29 device with crank (not shown), in which the connecting rod 29 is hinged to a vertical pin 30, projecting from the upper portion of the body of the slide 15. On the side of the oscillating member 13 facing toward the connecting rod 29, a second cam means 31 is provided comprising a section having a non-active outline 33 and a section having an active outline 32 cooperating with an extension 34 of the connecting rod 29 provided with a further rolling body 35.

[0016] As shown in Figure 4, the tubular bodies 26 are interconnected by a pair of crossroads 38 each provided with a hole 39, through which the middle portion of the cam means 19 is inserted; each holes 39 is large enough not to interfere with the cam means in any angular position, that may be reached by the cam means under the action of the said driving means 27.

[0017] Between the oscillating member 13 and the slide 15 elastic means 36 are interposed, advantageously, for instance, compression springs adjustable by means of screw adjusting means 37 capable of keeping the oscillating member 13 pushed upward, so that the active profile 33 is engaged against the upper further rolling body 35 of the connecting rod 29.

[0018] The arrangement is such that, when the connecting rod 29 causes the slide 15 to run along a direction F1 for spreading the decorating product 9 on the silk screen 10, the further cam means 31 is opposed by the further rolling body 35 of the connecting rod 29 and the printing squeegee 16 is kept lifted from the silk screen 10, while the spreading squeegee 14 spreads the decorating product 9 on the mesh of the silk screen 10. On the contrary, when the connecting rod 29 after passing a dead point position at the end of a spreading stroke along the direction F1, pushes the slide 15 in a direction F2 opposite to the direction F1, to perform a printing stroke, the connecting rod 29 moves the further rolling body 35 on the non-active portion 32 of the cam 31 and the spring means 36 may rotate the oscillating member 13 around the pin 12 as far as the rolling body 23 engages the outer surface of the cam means 19 facing it. In this situation, the spreading squeegee 14 is no more in contact with the decorating product 9, while the printing squeegee 16 presses against the meshes of the silk screen 10, to force the decorating product 9 through them.

[0019] In a certain angular position, if the outer surface of the cam means 19 interacting with the rolling body 23, is an even surface, the printing pressure, that is the pressure between the printing squeegee 16 and the tile 2, is constant during the printing stroke.

[0020] Otherwise, if the outer surface of the cam means 19 interacting with the rolling body 23, is an uneven surface, the printing pressure is variable along the printing stroke, and, exactly, increases when the rolling body 23 approaches the tile 2 and decreases when it goes away from the tile.

[0021] In addition, a variation of the printing pressure may be obtained when the outer surface of the cam means 19 interacting with the rolling body 23, is even, if one acts on the driving means 27 of the cam means 19 during the printing stroke F2, causes the cam means to angularly rotate around the axis A.

[0022] As illustrated in Figure 5, on the outside of the pair of guide rods 11, a pair of adjusting rods 19a is supported, each having ends provided with respective end portions 20a, which may be angularly positioned in holes made in support blocks 22a; each adjusting rod 19a being adjustable around the respective longitudinal axis A, independently of the other rod through driving means 27.

[0023] In this embodiment, the oscillating member 13a is provided with a pair of fork appendixes 24a, in which respective wheels 23 free to rotate on the adjusting rods 19a.

[0024] The adjustment of the printing pressure may be obtained in an independent way at each end of the printing squeegee 16, because the oscillating member 13a is provided with a pair of joint means 40, advantageously hinge joints, that make the fork appendixes 24a released with respect to the body of the oscillating member 13a, in a vertical plane. In addition, the joint means 40 are caused to cooperate with respective elastic means that, during the spreading stroke, keeps the fork appendixes 24a pressed against related portions of the oscillating member 13a.

Claims

1. Printing group (8) comprising decorating means (14, 16) capable of decorating objects (2), the said decorating means (14, 16) being joined to mobile support means (15, 13, 26; 15, 13a, 26) operated from respective driving means (29) to perform a reciprocating motion, adjusting means (18; 19, 20, 23, 27) arranged to adjust the position of the said decorating means (14, 16) with respect to said objects (2), characterised in that, said adjusting means (18; 19, 20, 23, 27) comprises a sensitive element (19, 20, 27; 19a, 20a, 27) that is not carried by said support means (15, 13, 26; 15, 13a, 26).

2. Printing group (8) according to claim 1, wherein said sensitive element (19, 20, 27; 19a, 20a, 27) comprises at least an elongated body (19) having at least an end constituting a tang (20) rotatably joined to a frame body (22).

3. Printing group (8) according to claim 2, wherein said elongated body (19) is substantially cylindrical.

4. Printing group (8) according to one of claims 2 or 3, wherein said elongated body (19) and said tang (20), or, respectively, tangs, have respective longitudinal axis (A, B), which do not coincide with each other.

5. Printing group (8) according to one of the preceding claims, wherein said sensitive element (19, 20, 27; 19a, 20a, 27) is joined to driving means (27).

6. Printing group (8) according to claim 5, wherein said driving means (27) are motorised.

7. Printing group (8) according to one of the preceding claims, wherein said support means (15, 13, 26; 15, 13a, 26) comprises an oscillating portion (13) supported by hinge means (12, 25) to a translating portion (26), said oscillating part (13) having a rolling body (23) that acts on said sensitive element (19).

8. Printing group (8) according to claim 7, wherein those adjustment means (18) that are separate from said sensitive element (19) are coupled with said oscillating portion (13).

9. Printing group (8) according to one of claims 2 to 8, wherein said sensitive element (19, 20, 27) is interposed between guide means (11) of said support means (15, 13, 26).

10. Printing group (8) according to one of claims 2 to 8, wherein said at least one sensitive element comprises a pair of sensitive elements (19a, 20a, 27), that are positioned on the outside of guide means (11) of said support means (15, 13a, 26).

11. Printing group (8) according to one of claims 7 to 10, wherein said oscillating portion (13a) is equipped with joint means (40) capable of allowing the respective ends to be independently moved.

12. Printing group (8) according to one of the preceding claims, characterised from that, it is associated with a silk-screen machine to decorate said objects (2).

Drawing