EP0937540A2

EP0937540A2 - Sanding-polishing machine for slabs, tiles and the like

Info

Publication number: EP0937540A2
Application number: EP99830085A
Authority: EP
Inventors: Paolo Cuoghi
Original assignee: Onix SRL
Current assignee: Onix SRL
Priority date: 1998-02-24
Filing date: 1999-02-18
Publication date: 1999-08-25
Also published as: EP0937540A3; IT1305459B1; ITMO980039A1

Abstract

The invention relates to a sander-polisher machine for slabs, tiles and the like, which comprises a mobile plane (1) for the slabs or tiles (2) conveying the latter in a predetermined direction. Above the mobile plane (1) are located a plurality of rotating frontally-acting sanders (3) having rotation axes which are perpendicular to the mobile plane (1) and to the advancement direction of the tiles (2). The frontally-acting sanders (3) are located above the mobile plane (1) and operate contactingly with at least a part of the upper surface (20) of at least one tile (2) situated on the mobile plane (1) in such a way that the upper surface (20) is entirely covered by a sanding action of the frontally-acting sanders (3) acting in a perpendicular direction to the advancement direction of the tiles (2).

Description

In particular, though not exclusively, the invention is usefully applicable for sanding-polishing all types of ceramic tiles, including glazed tiles.
The invention is especially advantageous for polishing surfaces often referred to as "structured", where the top surface of the support is not uniformly glazed, but varied zone-by-zone so as to give the impression of a relief-type decoration or design.
In tiles of the above-described type, in order to achieve a desired effect, the tiles are polished only in the parts in relief. The background areas should remain dull or at least less polished so as to achieve the desired aesthetic effect. The fact is, however, that all tiles exhibit deformations due to the firing process, rendering the top surface of the tiles not perfectly flat.
As these deformations are of significant entity, exceeding the thickness of the layer of glaze, the polish obtained using known devices does not achieve satisfactory results as inevitably the sanding away of glaze tends to flatten the top surface of the tiles and not to follow the undulations of the uneven surface. The lowest-lying glaze is therefore often left unsanded and unpolished, while the highest-lying glaze is sometimes totally removed, revealing the underlying support.
This grave defect in the prior art means in effect that existing means for sanding and polishing are inapplicable to this type of tile, as the level of rejects and the quality of the few acceptable tiles remaining are impossible to sustain. Structurally the prior art teaches various configurations.
In some cases machines are used which have a single large-dimension tool, covering the whole tile surface, at least in a perpendicular direction to the advancement direction.
In other cases single tools are also used, though of small diameter, which are provided with alternating oscillating motion in a transversal direction to that of tile advancement, so as to cover the whole transversal dimension of the tile itself. This type of realisation, however, apart from the drawbacks mentioned above, has other disadvantages attributable to the range of the oscillating motion of the tool, which contribute to a lack of uniformity in the worked result.
The main aim of the present invention is to obviate the above-described limitations and drawbacks in the prior art.
An advantage of the present invention consists in its constructional, functional and operative simplicity.
A further advantage of the present invention consists in the possibility of easily and rapidly converting it to suit the format of the slabs or tiles being worked. These aims and advantages and more besides are all attained by the present invention, as it is characterised in the appended claims.
Further characteristics and advantages of the present invention will better emerge from the detailed description that follows of a preferred but non-exclusive embodiment of the invention, illustrated purely by way of a nonlimiting example in the accompanying figures of the drawings, in which:
figure 1 is a schematic plan view from above;
figure 2 is a schematic section made according to line II-II of figure 1;
figure 3 is an enlarged-scale drawing of a detail of figure 2;
figures 4 and 5 are schematic sections made according to line II-II relating to two different operative configurations.
With reference to the figures, 1 denotes in its entirety a mobile rest plane, constituted for example by a horizontal conveyor belt, on which slabs or tiles 2 are translated one after another in the direction indicated by the arrow 11. The tiles 2 exhibit an upper surface 20 which is to be sanded and polished. A position-adjustable platform 5, also horizontal, is located above the plane 1 and mounted on a support 6.
The support 6 is mounted on fixed guides 12 arranged transversally to the plane advancement direction and can therefore translate horizontally in two directions perpendicular to the advancement movement of the plane 1. In particular, the support 6 is commanded by a crank mechanism to make straight alternating movements along the guides 12. The total extension of these alternating movements can be adjusted, for example by varying the length of the con rod of the crank.
The platform 5 can be rotated about the support 6 about an axis which is central and perpendicular to the plane 1. A plurality of identical chuckheads 4 are arranged on the platform 5; these have parallel axes and are contained within a same plane which is perpendicular to the rest plane 1 forming an angle (with respect to the advancement direction indicated by arrow 11) which is variable in relation to the orientation at which the platform 5 is set, and which is not near 90°.
Each of the chuckheads 4, which have their rotation axes perpendicular to the plane 1, can freely translate by a limited entity in an axial direction with respect to the platform 5. For this purpose each chuckhead 4 is rotatably supported in a sleeve 14 coupled axially slidably to the platform 5.
Each chuckhead 4 also has solidly connected to it a cogged pulley 9 predisposed to couple with a transmission belt 8 (cogged on both sides), which has the task of drawing the chuckhead 4 in rotation.
All of the chuckheads 4 are drawn in rotation by means of a single mechanical transmission, actuated by a motor 7 which is solidly mounted on the platform 5, and which uses a single belt 8 wound about the cogged pulleys 9 provided on the chuckheads 4 in such a way as as to rotate any two adjacent chuckheads 4 in opposite directions.
In a further embodiment of the invention the belt winding pattern for drive transmission could be arrainged so that the chuckheads 4 all rotate in a same direction.
Each chuckhead 4 bears a multi-cutting tool or frontally-acting sander 3 predisposed above the mobile rest plane 1, which sander 3 operates contactingly on at least a part of the upper surface 20 of at least one slab or tile 2 situated on the plane 1.
In particular, the chuckheads 4 and therefore the sanders 3 (which are all the same and have a small diameter with respect to the tiles to be sanded-polished, preferably less than 150mm) are arranged in such a way that the surface 20 of the tile 2 is totally worked by the action of the sanders 3 perpendicularly to the advancement direction of the tiles 2 themselves, indicated by the arrow 11. In other words, the vertical plane containing the rotation axes of the chuckheads 4 forms, together with the advancement direction, an acute angle sufficient for the contiguous contact scuffs caused by the work of each of the sanders 3 on the tile upper surfaces 20 to be superposed at least minimally by the work of other sanders 3. This superpositioning can be more or less accentuated according to the angle of orientation the platform 5 is made to assume.
The possibility of rotating the platform 5 means that the invention can be adapted to suit the format of the tile to be sanded, as is clearly shown by the two different configurations illustrated in figures 4 and 5.
A small tile requires a small angle between the plane containing the axes of the chuckheads 4 and the advancement direction, with a considerable ensuing superpositioning of the above-mentioned contact scuffs, whereas a large tile requires a greater angle between the plane containing the axes of the chuckheads 4 and the advancement direction, with a consequently smaller superpositioning of the contact scuffs.
The sanders 3 are not only identical in terms of size and structure, they also frontally exhibit the same abrasive granulometry.
The frontal surface of each sander 3 is elastically deformable and is afforded or located on an elastically-deformable support 30.
This enables the frontal surface to adapt to the irregularities (whether deliberate or not) which characterise the upper surfaces 20 of the tiles 2 and therefore sand them efficiently, following at least partially the outline surface of the tile upper surfaces. This sanding operation is further enhanced by the vertical freedom of the chuckheads 4 bearing the sanders 3.
The constancy of the force with which the single sanders 3 press on the tile upper surface is guaranteed by the total weight of the whole mobile unit comprising the chuckhead 4, the sanders 3 and connected organs plus an added weight if necessary.
In a further embodiment, the above-mentioned weight could be replaced by a spring.
In a further embodiment, not illustrated in the accompanying drawings, the chuckheads 4 may not be free to translate vertically, the elastic deformability ofthe sanders 3 and the supports 30 alone performing the task of following the deformed profile of the upper surface 20 of the tiles 2. For this purpose the support 6 is structured so as to be height-adjustable, obviously causing the sanders 3 also to be height-adjustable with respect to the upper surfaces of the tiles 2 arranged on the mobile plane 1. Thus, with the resulting rigid vertical connection of the chuckheads 4, and the possibility of height-regulating the sanders 3, a pressure of predetermined and considerable entity can be exerted on the tiles 2.
During normal operation, once the platform 5 orientation has been adjusted with respect to the advancement direction of the plane 1 according to the transversal dimensions of the slab or tile to be sanded-polished, so that a full overall result is obtained, the sanders 3 work on the tile upper surfaces 20, exerting constant vertical action thereon and following the normally uneven profile thereof.
Thus, during sanding a more or less uniform layer of glaze is removed from the tile surface, independently of the degree and distribution of the tile upper surface undulations.
The uniformity of the final working operation over the whole tile surface is guaranteed not only by the fact that the described sanders 3 are identical, but also by the alternating motion vertically to the advancement direction with which the support 6 and thus the whole sander 3 group can be provided.
The frequency of this transversal motion can be advantageously regulated in combination with the plane 1 advancement speed.
To obtain a final polish on the tiles 2, it is usual practice to arrange a number of machines in series, which are similar to the above-described machine but which are distinguished by having sanders with progressively lower abrasion grades.
The invention can be used to work many and widely-varied types of materials. It is sufficient to adapt certain characteristics thereof, such as the degree of elastic deformability of the sanders 3 and the weight the sanders 3 exert on the advancing tiles.
The invention is in any case distinguished by its high production speed.

Claims

A sander-polisher machine for slabs, tiles and the like, characterised in that it comprises:

a mobile rest plane (1) for the tiles (2) on which the tiles (2) are conveyed in a predetermined advancement direction;

a plurality of rotary multi-cutting tools, namely frontally-acting sanders (3), predisposed with rotation axes thereof perpendicular to the mobile plane (1) and the advancement direction of the tiles (2);

the frontally-acting sanders (3) being predisposed above said mobile rest plane (1) in order to operate contactingly on at least a part of an upper surface (20) of the tiles (2) situated on the mobile plane (1), the upper surface (20) being totally covered by a sanding action of said frontally-acting sanders (3) operating in a vertical direction to said advancement direction of the tiles (2).
The machine of claim 1, characterised in that the frontally-acting sanders (3) are supported on chuckheads (4) having reciprocally parallel axes, each of which chuckheads (4) can translate in an axial direction and each of which can press and keep pressed with a predetermined force a frontally-acting sander (3) against the upper surface (20) of the tile (2) it is destined to work upon.
The machine of claim 2, characterised in that the chuckheads (4) are mounted on an orientable platform (5) which is mounted on a support (6) which can alternating translate perpendicularly to the advancement direction of the mobile plane (1).
The machine of claim 3, characterised in that the chuckheads (4) have reciprocally parallel axes lying within said same plane which is perpendicular to said mobile plane (1), and in that the same plane forms an angle with the advancement direction of the tiles which is not 90°.
The machine of claim 4, characterised in that the platform (5) can be oriented with respect to the support (6) about a central axis thereof which is perpendicular to the mobile plane (1).
The machine of claim 1, characterised in that the frontally-acting sanders (3) exhibit a frontal working surface which is abrasive, elastically deformable and either afforded directly on or predisposed on an elastically-deformable support (30).
The machine of claim 5, characterised in that the frontally-acting sanders (3) exhibit a frontal working surface which is abrasive, elastically deformable and either afforded directly on or predisposed on an elastically-deformable support (30).
The machine of claim 1, characterised in that the frontally-acting sanders (3) have a relatively small diameter with respect to dimensions of slabs or tiles (2) to be worked on.
The machine of claim 7, characterised in that the frontally-acting sanders (3) have a relatively small diameter with respect to dimensions of slabs or tiles (2) to be worked on.
The machine of claim 9, characterised in that the chuckheads (4) are driven in rotation by a mechanical transmission, actuated by a motor (7) solidly constrained to the platform (5), which transmission is achieved by means of a belt cogged on either side thereof which winds about cogged pulleys (9) constrained to the chuckheads (4), resulting in opposite rotation directions of adjacent pulleys (9).
The machine of claim 10, characterised in that the frontally-acting sanders (3) are of the same size.
The machine of claim 11, characterised in that the frontally-acting sanders (3) have the same abrasive granulometry.
The machine of claim 3, characterised in that the alternating translating motion of the support (6) in a perpendicular direction to the advancement direction ofthe mobile plane (1) exhibits a frequency which is correlated to the advancement speed of the tiles (2) on said mobile plane (1).
The machine of claim 12, characterised in that the alternating translating motion of the support (6) in a perpendicular direction to the advancement direction of the mobile plane (1) exhibits a frequency which is correlated to the advancement speed of the tiles (2) on said mobile plane (1).
The machine of claim 12, characterised in that the means for keeping a frontally-acting sander (3) contactingly against a surface (20) of a tile (2) are constituted by an overall weight of the chuckhead (4), the frontally-acting sander (3) and organs connected thereto, and an additional weight (10) which can be optionally added to reach a desired total weight.
The machine of claim 12, characterised in that the means for keeping a frontally-acting sander (3) contactingly against a surface (20) of a tile (2) are constituted by a spring operating between a chuckhead (4) and the orientable platform (5).
The machine of claim 1, characterised in that the frontally-acting sanders (3) are supported on chuckheads (4) having reciprocally parallel axes which are perpendicular to said mobile plane (1) and which are axially solidly connected to an orientable platform (5) which is mounted on a support (6); said support (6) being able to translate alternatingly in a perpendicular direction to the advancement direction of the mobile plane (1); each of said chuckheads (4) being axially constrained to said platform (5) at a prefixed distance which enables a frontally-acting sander (3) to be kept pressed at a predetermined pressure against the surface (20) of the tile (2) with which it is destined to come into contact.