STONES AND THE LIKE”

TECHNICAL FIELD OF THE INVENTION

The present invention regards a machine and a method for machining ceramic products, natural stones and the like, e.g. ceramic tiles, stone materials, glass, composite materials, etcetera.

In particular, the present invention regards a machine and a method for machining ceramic products, natural stones and the like, with measurement of each of the partial machining operations carried out on the products.

STATE OF THE ART

With particular reference to the field of the ceramic industry for the manufacturing of products such as tiles, plates or bricks, or natural stones, it is known to carry out the machining, such as the calibration and/or squaring of the edges so as to bring the aforesaid products within the requested size and/or geometric tolerances.

For the execution of the size calibration and squaring, the prior art provides calibrator machines, otherwise known as squaring devices, which provide for the transfer of the squareable element to be squared along a path during which the element itself is machined at two opposite edges, parallel to the advancement direction, by a plurality of mandrels with opposite front grinding wheels.

Each grinding wheel is rotated at a pre-established speed by a motor and it can remove more or less material as a function of the machining position in the product advancement path.

At the start of the path, the machine is normally equipped with wheels with abrasive material for rough-shaping, which remove more material, and subsequently with wheels with abrasive material for finishing, which remove less material and which render the surface smoother.

The wheels are distributed in opposite pairs along the path and the distances between the two opposite wheels of each pair are adjustable closer to and away from the product part being machined and as a function of the width size to be obtained. As stated above, the moving closer or away adjustment also depends on the position occupied by the pair of wheels along the path, since in fact such machining is obtained progressively - removing material from the products in subsequent steps, up to the obtainment of the final dimensions and surface roughness requested for the products. The adjustment of the position of the wheels is carried out by an operator based on his/her experience or on the noise of the machine or on the electrical power required by the motors that drive the wheels.

Following wear of the wheels, the operator must periodically compensate for the position of the same wheels in order to obtain the removal of material necessary for that machining step.

This procedure is difficult and, depending also on the experience of the operator, does not always ensure satisfactory results. For example, it can happen that following wear of the wheels, a machining step removes less material than that expected.

There is therefore the need to improve the technique of squaring ceramic products, natural stones and the like, by means of grinding wheels.

DE10051253A1 teaches a solution according to the state of the prior art.

OBJECTS OF THE INVENTION

Therefore, the main object of the present invention is to improve the state of the art of the field of machines for squaring of ceramic products, natural stones and the like. In the scope of such task, one object of the present invention is to provide a machine and a method for machining ceramic products, natural stones and the like which allows an easy adjustment of the position of the wheels in each machining step, without requiring the operator to have any particular experience.

Another object of the present invention is to provide a machine and a method for machining ceramic products, natural stones and the like which allows automating the adjustment of the position of the wheels in each machining step.

Still another object of the present invention is to provide a machine and a method for machining ceramic products, natural stones and the like which can be attained with limited costs.

These and still other objects of the present invention are achieved by a machine for machining ceramic products, natural stones and the like according to claim 1.

A method is also provided for machining ceramic products, natural stones and the like according to claim 10.

The dependent claims refer to preferred and advantageous embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will be more evident from the detailed description of a non-exclusive embodiment of a machine for machining ceramic products, natural stones and the like, according to the present invention, given as a non-limiting example in the enclosed set of drawings in which: figure 1 is a top schematic view of a machine for machining ceramic products, natural stones and the like according to the present invention;

figure 2 is a side schematic view of the machine for machining ceramic products, natural stones and the like pursuant to the preceding figure;

figure 3 is a top schematic view of a detail of the machine pursuant to the preceding figures, according to one version of the present invention;

figure 4 is a top schematic view of a detail of the machine pursuant to figures 1 and 2, according to another version of the present invention;

figure 5 is a top schematic view of a detail of the machine pursuant to the figures 1 and 2, according to a further version of the present invention;

figure 6 is a partial section schematic view of the machine for machining ceramic products, natural stones and the like pursuant to the preceding figures;

figures 7 and 8 illustrate several details of the machine for machining ceramic products, natural stones and the like pursuant to the preceding figures.

EMBODIMENTS OF THE INVENTION

With reference to the enclosed figures, a machine for squaring ceramic products, natural stones and the like is indicated with the reference number 1 in its entirety.

Ceramic products, natural stones and the like are generally indicated as elements A, they translate in the machine according to advancement direction X and comprise two edges B to be machined; the edge B is arranged substantially parallel to the advancement direction X of the elements A.

The machine 1 comprises a series of pairs of driven grinding wheels 2, i.e. at least two pairs of driven grinding wheels 2; in addition, one or more pairs of driven grinding wheels 3 can be provided, arranged tilted or tiltable for achieving the smoothing on the edges.

Each edge B is machined by the machine 1 by means of at least one wheel 2 and possibly also by means of a tilted or tiltable wheel 3.

The machining operations carried out by the driven grinding wheels 2 on the elements A are the following: squaring of the shape of the slab, calibration of the width size, grinding of the surface of the edges; the tilted or tiltable driven grinding wheels 3 carry out the machining work of chamfering or smoothing.

Each driven grinding wheel 2 is provided with adjustment means 21 of the position with respect to the edge B; also each tilted or tiltable driven grinding wheel 3 can be provided with means 31 for adjusting the position with respect to the edge B of the elements A.

The machine 1 comprises a support structure 4 for at least one conveyor belt 5 for transferring and advancing on a respective support plane 6 of the elements A according to a specific advancement direction X.

Pressing members 7, e.g. rollers or belts, are also present that are adapted to abut against the elements A driven by the conveyor belt 5: the pressing members have movement synchronous with the belt 5, and allow stably retaining the elements A during the advancement and machining of the same.

The particular characteristic of the present invention is that the machine 1 comprises measuring means 8 arranged downstream of each wheel 2, with respect to the advancement direction X, and possibly also downstream of the measuring means 8 arranged downstream of each tilted or tiltable wheel 3; the measuring means 8 allow measuring the distance L of the edge B with respect to a reference of the machine 1.

By means of the distance L, the measuring means 8 are capable of calculating, hence they indirectly detect, a measurement of the machining carried out on the edge B by the wheel 2, or by the wheel 3, which immediately precedes the measuring means 8. Figure 3 illustrates a version of the present invention in which the measuring means 8 comprise contact measuring probes 9, for example of electromechanical type.

Each probe 9 is arranged downstream of each wheel 2, or wheel 3, so as to measure the distance L after each machining carried out, intermittently, i.e. the contact with the edge B can occur periodically, after each machining, so as to verify the measurement actually attained in that machining step.

Figure 4 illustrates another version of the present invention in which the measuring means 8 comprise an ultrasound distance measuring device 10.

Since there is no contact with the element A, the measurement of the distance L can also occur continuously; the verification of the edge B is analogous to that of the preceding version.

In figures 5, 7 and 8, another version of the present invention is illustrated in which the measuring means 8 comprise a laser distance measuring device 11.

The measuring device 11 comprises an emitter 12 of a light or electromagnetic radiation 13, and a receiver 14 which detects a radiation 15 (figures 5 and 7) reflected by the edge B of the element A, due to the emitted radiation 13.

For an improved detection of the radiation 15 by the receiver 14, a device 16 can also be provided for blowing a jet S of compressed air (figure 8) in order to repel the powder that may be present.

Also for this version, since there is no contact with the element A, the measurement of the distance L can also occur continuously; the verification of the edge B is analogous to that of the preceding versions.

The measurement of the distance L directly on the edge B of the element A therefore allows evaluating the amount of material removal carried out by the specific driven grinding wheel 2 and comparing it with a predefined value based on experimental or calculated data, for that specific machining step.

The deviation between the actual value and the predefined value is shown in a display that can be found next to the specific driven grinding wheel 2 or 3, or in a centralized display for all the wheels 2 or 3.

The operator of the machine 1 who detects an excessive deviation in a specific machining step, due to a specific driven grinding wheel 2 or 3, can thus adjust and/or compensate for the position of the same wheel by means of the adjustment means 21 or 31; for example, an excessive deviation between the actual value and the predefined value for that machining step can be caused by the wear of the abrasive disc 22 (figure 6).

Naturally, this procedure can be repeated by the machine 1 operator for all the machining steps in which an excessive deviation is detected between the actual value and the predefined value.

Due to the present invention, the operation of adjusting and/or compensating for the driven grinding wheels is rendered simpler and quicker, and is independent of the experience of the operator.

According to another version of the present invention, the actuation of the adjustment means 21 or 31 can occur in a completely automatic manner.

The machine 1 can comprise a wiring 17 and a control unit 18 (figure 6), and by means of the wiring 17 the control unit 18 is in communication with all the measuring means 8 and all the adjustment means 21 or 31.

The measurement signal L coming from each of the measuring means 8 is sent to the control unit 18, which if necessary provides for actuating the adjustment means 21 or 31 of the wheels 2 or 3 that are situated upstream of the respective measuring means 8; such actuation is attained by means of suitable logic means of the control unit 18, for example by means of a software.

However, in addition to that stated above, the control unit 18 could, as a function of the data received by the measuring means 8, displace, e.g. advance or move back the wheels on one side (e.g. operator side) and those on the opposite side (e.g. machine side) in a coordinated manner, so as to simultaneously maintain correct both the positions of the wheels as a function of the actual width and position of the tiles, and the symmetry of the belt or series of tiles being processed with respect to a horizontal longitudinal axis.

For such purpose, each pair of driven grinding wheels 2 comprises a first wheel 2 on one side (operator side) of the machine set to machine a first edge B of the elements or tiles A and a second wheel 2 on the other side (machine side) of the machine set to machine a second edge B opposite and parallel to the first of the elements A to be machined.

With reference to such aspect, when the elements or tiles A are loaded on the conveyor belt 5, the same might not be centered with respect to the longitudinal axis of the machine - such axis being parallel to the advancement direction of the belt - but rather offset with respect to such axis. If this is the case, the measuring means 8 would detect a distance from the edge B of the elements A that would be a function of such non- alignment and which would affect the measurements and evaluations pertaining to the wear of the wheels 2.

Therefore, in accordance with the present invention, the control unit 18 once it has received values detected by the measuring means 8 - in particular by a part of or by all the measuring means 8 on one side or the operator side and a part of or all the measuring means 8 on the other side or machine side - can be set in a manner such that it is capable of evaluating if the elements A are non-aligned with respect to the longitudinal advancement axis of the machine and, if necessary, adjusting the position or consequently moving the respective wheels 2, such to arrange a wheel or a row of wheels 2 on one side of the machine in a symmetric position with reference to the longitudinal advancement axis of the elements A with respect to the other wheel or to the other row of wheels 2 on the other side of the machine.

In substance, the wheels of one pair or of multiple pairs or of all the pairs of wheels on both sides of the machine are arranged one substantially symmetric with respect to the other, with respect to the actual longitudinal axis of the elements A and not with respect to the longitudinal axis of the machine, which ideally corresponds to that of the elements A, but in practice could different therefrom.

As seen, the system knows the position of the wheels 2 and the position of the middle line of the machine and, due to the measuring means 8, it can calculate the difference between the actual axis of the elements A and theoretical axis ideally equivalent to that of the machine, and on the basis of the above-indicated evaluations, move the wheels or better yet the rows of wheels on one side of the machine so as to move them closer to or away from the wheels or better yet from the row of wheels on the other side of the machine.

The evaluation of the actual axis of the elements A can be obtained by means of a mean of the values derived by the measuring means 8 on one side and of the measuring means 8 on the other side.

Clearly, the evaluation of the actual axis of the elements A to be machined is made continuously, and since the tiles A are progressively fed onto the conveyor belt, such axis can change. In addition, such evaluation is conducted simultaneously with the evaluations pertaining to the above-described operations of adjustment and/or compensation.

In addition, as is known, all the mechanical clearances are a serious detriment to the quality of the mechanical machining operations, since they induce vibrations on the tools or wheels, which rotate at very high speeds. In the same manner, the clearances on possible screws or control components of the adjustment means 21 or 31 which adjust the position of the wheels 2 can be quite damaging.

In order to resolve the problem deriving from the clearances, usually one employs high- precision control screws lacking clearance (with recirculation of walls and preloaded) or one intervenes at the software level.

With regard to such aspect, it is known that the clearances do not induce vibrations since the gap between screw and nut screw does not intercept the flow of the load that is imparted by the wheel, since screw and nut screw are always thrust together. It is easy to obtain thus condition when the adjustment is in the direction of pushing a wheel 2 towards the elements A to be machined, while it is more difficult when it is necessary to loosen in order to reduce the quantity of removed material and hence a wheel 2 is pushed away from the elements A.

If it is necessary to move a wheel 2 back with respect to an element A to be machined, if one only completes a retreating travel by acting on the screw of the adjustment means, the gap between screw and nut screw would be on the wrong side or better yet on the side such to increase the present clearances.

In order to remedy such problem, the control unit 18 can be such that when it is necessary to move one or more wheels 2 back or away from the elements A to be machined by a first or specific distance Dc, the unit 18 moves back or away the wheel or wheels 2 from the elements A by a second or greater distance, e.g. equal to 1.5 times or double or triple the first quantity or distance, before then newly advancing or moving the wheel or wheels 2 closer to the respective edge B of the respective element A to be machined up to bring such wheels actually to the first or specific distance. In this manner, the control screw of the adjustment means 21 always works thrustingly, bringing the clearances onto the correct side and reducing or eliminating the problem correlated therewith.

Also forming the object of the present invention is a method for machining elements A, such as ceramic products or natural stones and the like, the elements A being provided with-two edges B to be machined, comprising the steps of transporting and advancing the elements A according to a specific advancement direction X on a respective support plane 6, the edge B being arranged substantially parallel to said advancement direction X, machining the edges B by means of driven grinding wheels 2 provided with adjustment means 21 of the position with respect to the edge B of the elements A, measuring a distance L of said at least one edge B with respect to a reference of the machine 1 , by means of measuring means 8 arranged downstream of each wheel 2, with respect to the advancement direction X, and calculating, by means of the distance L, a measurement of the machining work on the edge B carried out by the wheel 2 which immediately precedes said measuring means 8.

The method also comprises the steps of providing a predefined value based on experimental or calculated data, for a specific machining step due to the specific wheel 2, comparing the predefined value with the measurement of the machining carried out on the edge B by the specific wheel 2 and performed by the measuring means 8, so as to present on a display the deviation between the actual value and the predefined value for that specific machining step.

A method according to the present invention can comprise steps for arranging a wheel or a row of wheels 2 on one side of the machine in a symmetric position with reference to the longitudinal advancement axis of the elements A with respect to the other wheel or to the other row of wheels 2 on the other side of the machine and/or for reducing the mechanical clearances according to that described above relative to a machine in accordance with the present invention.

The invention thus conceived is susceptible of numerous modifications and variations, all falling within the scope of the inventive concept.

In addition, all details can be substituted with other technically equivalent elements.

In practice, the materials used, as well as the contingent shapes and sizes, can be of any type in accordance with the requirements, without departing from the protective scope of the following claims.