Unit for decorating ceramic products

Abstract

 A unit for decorating ceramic products (2) with respective decorations (3) has a decorating roller (10) defined by an elastically deformable tubular body (12) having a given longitudinal axis (11), and by two covers (19) for axially closing the tubular body (12); the tubular body (12) and the covers (19) defining a chamber (22) connectable pneumatically to a pneumatic device (23) supplying a pressurized gas.

Description

[0001] The present invention relates to a unit for decorating ceramic products, and in particular to a unit for decorating ceramic products with liquid enamel.

[0002] In the decoration of ceramic products, a unit is known comprising a conveyor device, which has a substantially horizontal conveying surface, and feeds the ceramic products successively in a given travelling direction through a decorating station equipped with a decorating roller.

[0003] The decorating roller is located over the conveying surface, and comprises an elastically deformable tubular body, which is mounted to rotate about a respective longitudinal axis crosswise to said travelling direction, is open axially outwards, and is bounded externally by a cylindrical surface substantially coaxial with the longitudinal axis.

[0004] The tubular body has a number of cup-shaped cavities, each of which opens outwards at said cylindrical surface, receives and retains a given quantity of liquid enamel, and defines, singly or together with other cavities, a decoration to be reproduced on the ceramic products.

[0005] The unit also comprises a pressure device fitted inside the decorating roller to deform the tubular body elastically and keep it, in use, substantially contacting the ceramic products to be decorated.

[0006] Known units of the above type have various drawbacks, mainly on account of the pressure device which makes them relatively complex and expensive.

[0007] Known units of the above type also have the further drawback of being fairly inaccurate, on account of the thrust exerted on the tubular body by the pressure device being difficult to control and varying, for example, alongside wear of the pressure device.

[0008] It is an object of the present invention to provide a unit for decorating ceramic products, designed to eliminate the aforementioned drawbacks, and which is cheap and easy to produce.

[0009] According to the present invention, there is provided a unit for decorating ceramic products, as claimed in Claim 1.

[0010] A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a first schematic side view, with parts removed for clarity, of a preferred embodiment of the unit according to the present invention;

Figure 2 shows a second side view, with parts removed for clarity, of the Figure 1 unit.

[0011] Number 1 in Figures 1 and 2 indicates as a whole a unit for decorating ceramic products 2 with respective decorations 3. In the example shown, each product 2 is substantially flat, is substantially in the form of a rectangular parallelepiped, and is bounded by two substantially parallel major lateral faces 2a.

[0012] Unit 1 comprises a known conveyor device (not shown), which has a substantially horizontal conveying surface 4, and provides for successively feeding groups 5 (only one shown in Figures 1 and 2) of products 2 in a given direction 6 and along a given path P. Groups 5 are equally spaced along surface 4, and each comprise a number of - in the example shown, three - products 2 aligned in a direction 7 crosswise to direction 6, and laid "flat" on surface 4, i.e. with one of respective faces 2a contacting surface 4.

[0013] Unit 1 also comprises a decorating device 8 located along path P, at a decorating station 9, and in turn comprising a decorating roller 10, which is located over surface 4, and is mounted to rotate, under the control of a known actuating device not shown, about a respective longitudinal axis 11 parallel to direction 7.

[0014] Roller 10 comprises a substantially cylindrical tubular body 12, which is substantially coaxial with axis 11, is open axially outwards, and is made of elastically deformable material.

[0015] Body 12 comprises a number of groups 13 of decorations 3, which groups are spaced about axis 11 with substantially the same spacing as groups 5 on surface 4, and each comprise a number of decorations 3, which are equal in number to products 2 in each group 5, are aligned with one another in direction 7, and are advanced in time with relative products 2.

[0016] Each decoration 3 is defined by at least one cavity 14, which is substantially cup-shaped, opens outwards at an outer cylindrical surface 15 of body 12, and contains and retains a given quantity of liquid enamel fed into cavity 14 by a known feed device 16.

[0017] Device 16 is mounted outside roller 10, and comprises a feed member 17, which feeds the liquid enamel onto surface 15, and cooperates with a flat doctor 18 for distributing the liquid enamel inside cavities 14.

[0018] Body 12 is closed axially by two covers 19, each of which is substantially cup-shaped with its concavity facing body 12, is fitted to body 12 in axially sliding manner, and is locked axially to body 12 by radial locking members (not shown) with the interposition of a sealing member (not shown).

[0019] Each cover 19 comprises a flat plate 20 crosswise to axis 11; and a shank 21, which projects axially from plate 20, extends coaxially with axis 11, and provides, together with the other shank 21, for connecting roller 10 to said actuating device (not shown).

[0020] Body 12 and covers 19 define a pneumatic chamber 22 communicating with a pneumatic circuit 23 for feeding pressurized gas, e.g. air, into chamber 22. Circuit 23 comprises a pressure regulating device 24, operation of which is feedback-controlled by a control device 25 for determining the actual pressure inside chamber 22, and for controlling device 24 to maintain a substantially desired pressure inside chamber 22.

[0021] Operation of unit 1 is easily deducible from the foregoing description, with no further explanation required.

[0022] Unit 1 has several advantages, mainly due to the fact that:

the air pressure inside chamber 22 is uniform, constant, and equal to a desired pressure;

roller 10 is relatively straightforward and inexpensive; and

in-service access to the inside of body 12 is prevented by covers 19.

Claims

1. A unit for decorating ceramic products (2) with respective decorations (3), the unit comprising a decorating roller (10), in turn comprising an elastically deformable tubular body (12) having a given longitudinal axis (11); and being characterized in that the decorating roller (10) also comprises two covers (19) for axially closing said tubular body (12); and a pneumatic chamber (22) defined by the tubular body (12) and by the covers (19), and connectable pneumatically to a pneumatic device (23) supplying a pressurized gas.

2. A unit as claimed in Claim 1, and also comprising control means (25) for determining an actual pressure inside said pneumatic chamber (22), and for controlling the pneumatic device (23) as a function of said actual pressure.

3. A unit as claimed in Claim 2, and also comprising pressure regulating means (24) for selectively controlling the pressure of the gas fed into said pneumatic chamber (22) as a function of a comparison between said actual pressure and a desired pressure.

4. A unit as claimed in any one of the foregoing Claims, wherein said tubular body (12) is bounded externally by a cylindrical surface (15) substantially coaxial with said axis (11), and comprises a number of cavities (14) opening outwards at said surface (15); each decoration (3) being defined by at least one said cavity (14).

5. A unit as claimed in Claim 4, and also comprising feed means (16) for feeding decorating material into said cavities (14).

6. A unit as claimed in any one of the foregoing Claims, and also comprising first actuating means for moving the decorating roller (10) and the product (2) for decoration with respect to each other in a direction (6) crosswise to said axis (11); and second actuating means for rotating the decorating roller (10) about said axis (11).

7. A unit as claimed in Claim 6, wherein said first and second actuating means are timed with each other to advance said product (2) in time with the relative said decoration (3).

Drawing