TECHNICAL FIELD

The present invention refers to the technical field of materials and food working, in particular it relates to a device and to a method for measuring the thickness of material laid on a moving support in respect to the measuring point, particularly suitable to gauge quality parameters of materials in batter, fats, crystalline and amorphous form in machine for their working.

BACKGROUND ART

There are known machines for refining material consisting of cocoa and similar products, reducing the dimension of granules of the material. Said machines are sometimes equipped with a known device to measure the thickness of the refined material laying on a support, for example a rotating cylinder. The thickness data of the material provides an indirect measure of the of the granules dimensions of the material and thus can be used to verify such quality index of the material and/or to control the refining process in order to maintain the dimensions of the granules under a fixed or adjustable threshold.

Said known devices fit for measuring the thickness of the layer of the material spread on and moved by the moving support, generally consisting in the cylindrical surface of a rotating roller around its own axis, they can be a kind trolley free to approach to and remove away from the support and equipped with wheels fit to match the external surface of the layer of material, of which the thickness is measured. A sensor of inductive or capacitive type installed on the trolley provides a signal regarding its own distance to the support. Since the distance of the sensor from the support depends on the thickness of the layer of material interposed between the wheels of the trolley and the support, said signal is proportional or correlated to the thickness of the material.

To reduce the soiling of the wheels, these latter can be very thin, can be braked or accelerated in respect to the motion of the material layer.

A disadvantage of said known devices consists in that despite the braking and the thin thickness of the wheels, they can become excessively dirty providing incorrect and erroneous signals.

Further disadvantage is that the known devices, due to the attritions, wear out in a very short time.

Other disadvantage consists in that said known devices and the respective known measuring methods, in case of irregularity of the layer or of the roller, can provide wrong signals and values.

Further disadvantage of said known devices consists in that, at least in some conditions, the wheels can sink into the layer to be measured provoking thickness measure errors.

Other disadvantage is that the vibrations can compromise the measuring precision of the thickness.

DISCLOSURE OF THE INVENTION

An object of the present invention is to propose a device to measure a thickness of a material almost without soiling and without errors caused thereby.

Other object of the present invention is to propose a measuring method and device, which can avoid or reduce measures errors of the thickness due to the irregularity of the layer and/or of the respective support.

Further object is to propose a device nearly wear - free, durable, reliable and not affected by

errors due to vibrations or to environmental agents.

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristics of the invention are highlighted in the following with particular reference to the attached drawings, in which:

- figure 1 shows a side view of the device for measuring a thickness, object of the present invention, connected to a upper roller of a rolling machine to refine the cocoa; - figure 2 shows an enlarged side view of the device of figure 1 ;

- figure 3 shows a back view, or from a point of view on the axis of the upper roller, of the device of figure 2.

BEST MODE OF CARRYING OUT THE INVENTION

With reference to the figures from 1 to 3, the numeral 1 indicates the preferred embodiment of the device, object of the present invention, to measure the thickness of a material M, for example cocoa powder or cocoa batter, laid on a support S consisting in the external face, nearly cylindrical, of a rotating roller R of a machine G to refine the cocoa, to form a layer L on said support. Obviously the invention provides that the device can be also connected to supports of machine to work and/or to refine vegetable origin material, such as grasses or, for example, paints and other similar products.

The device 1 comprises a supporting mean 2 at least for sensors, first 3, second 4 and third 5, positioned toward the layer L and the support S in nearly radial direction in respect to the roller and horizontally positioned.

The supporting mean 2 is fixed to a vertical arm 6 and approximately tangent to the roller R connected to a supporting frame F of the axial supports of the roller R.

In alternative, the invention provides that the arm 6 comprises translation means of known type, for example guide and belt type or worm gear type, and not shown, for moving the supporting means 2 in a parallel direction respect to the axis of the respective roller R to measure the thickness of the layer L in various transversal positions.

In the case of a supporter S constituted by a roller S whose axis can translate, for example, for the adjustment of the refinement or for compensations of dilatation or similar, the position of the supporting means 2 can be registered by means of the arm 6, or the signals of the sensors can be compensated by the control means. In alternative the arm 6 and the supporting means 2 can be fixed to the rotation axial supports of the roller in order to eliminate the relative movements between sensors and support S.

The sensors are reciprocally aligned and the first sensor 3 is interposed, and equidistant from, the others two sensors, second 4 and third 5.

The alignment straight line of the sensors, first 3, second 4 and third 5, is nearly parallel to the axis of the roller R. Eventual small parallelism errors affect in negligible manner on the measure of the layer.

The distance from each sensor 3, 4, 5 from the support S is enough bigger than the thickness of the layer L to avoid soiling and interferences with the material.

The sensors, first 3, second 4 and third 5, are orientated parallel one to the other and nearly orthogonal to the axis of the roller.

In particular, the first sensor 3 is of the type which can measure the distance from the sensor itself to the first surface faced thereto, preferably of laser type, and the sensors, second 4 and third 5, are of the type which can measure their distance from the support S, also in the presence of the layer L, preferably of inductive and/or capacitive type.

In alternative the invention provides that, vice versa, the first sensor is of the second type and that the sensors, second 4 and third 5, are of the first type or that, even generally, the first sensor 3 is of the type to measure its own distance from the support S also in the presence of the layer L, and the sensors, second 4 and third 5, are of the type to measure their own distance from the first surface S faced thereto, or vice versa.

Optionally, the supporting means 2 can be provided with at least a thermal detector fit to detect the temperature at least in the support area, sensed at least by the first sensor.

The first, second, third sensors and the thermal detector are connected to a thickness control mean, of known type and not shown, to which the respective signals of distance and temperature are transmitted.

The control means are of analogical electronic type or, preferably, digital type for memorizing and/or for filtering and/or for elaborating, on the base of memorized algorithms, values or sequences of the various received signals to provide at least the thickness of the layer L.

The operation of the device according to the method of the invention to measure the thickness of a material M spread on a roller support S cylindrical and also a little bit fusiform or irregular, provides starting from an initial condition in which the support S is not covered by the layer L:

- to provide the control means, by means of the first sensor 3, with a signal of the distance from the first sensor to the support S;

- to memorize, by means of the control means, at least a signal value of the distance from the first sensor to the support;

- to calculate, by means of the control means, the average signal value of the distances from each of the sensors, second 4 and third 5, to the support S, and to calculate and to memorize a correction value consisting in the difference between the said average value

and the memorized value of the signal of the distance from the first sensor to the support in order to allow the compensation of eventual cambers or irregularity of the support S;

- in a subsequent operational condition in which the support S in rotation is covered by the layer L of the material M, the method provides to provide the control means, by means of the first sensor 3, with the signal of the distance between the first sensor 3 and the layer L;

- to provide the control means, by means of the sensors, second 4 and third 5, with respective signals of their distances to the support; - to calculate, by means of the control means, an average value of at least a value of these latter signals provided by the second and third sensors, and to subtract to this latter average value the correction value to obtain at least a distance value calculated between the first sensor 3 and the support S;

- to subtract by means of the control means to of this latter distance value between the first sensor 3 and the support S a signal value of the distance signal from the first sensor

3 to the layer L obtaining a thickness value of the layer L.

The method also provides to obtain the value of the distance signals from the first sensor 3 to the support S and to the layer L, and the at least one value of the signals of the distances from each of the sensors, second 4 and third 5, from the support S, for example as elaborations to obtain average values, of the respective values of said signals calculated on one rotating period of the roller support or its multiple.

The method also provides to obtain, by means of an algorithm memorized in the control means, starting from the thickness values of the layer L, an index of the granularity of the material M that provides useful information about the granules dimensions of the material

M and in particular of the cocoa or chocolate. On the base of said index, which can be also very precise, the control means can check in feedback the operational parameters of the machine, for instance the distance or pressure between rollers or their rotation speed, in order to maintain the granules' dimensions under a fixed or adjustable threshold value.

A first variant of the device 1, which is comprehensible without any specific figure, provides that the supporting means 2 comprises only the first 3 and the second 4 sensors positioned toward the layer L and the support S as described in the preferred embodiment, and oriented approximately parallel one to anther and orthogonal to the support S.

In this variant the first sensor is of the type able to measure the distance from itself to the first surface faced thereto, preferably of laser type, and the second sensor 4 is of the type which is able to measure the distance from itself to the support, preferably of inductive and/or capacitive type, fit to provide a signal of the distance to the surface of the support S, also in presence of the layer L.

The operation of the first variant according to the method of the invention to measure the thickness of a material M, provides:

- in an operational condition in which the support S is covered by the layer L, to provide the control means, by means of the first sensor 3, with signals of the distance of the first sensor from to the layer L;

- to provide the control means, by means of the second sensor 4, with signals of the distance from the second sensor to the support S;

- to subtract, by means of the control means, the signal value of the distance from the first sensor to the layer L from of the signals values of the distance from the second sensor to the support S in order to obtain values related to the thickness of the layer L;

- in case whose two sensors are positioned at different distances from the support, the difference of the distances from the support S of the two sensors 3, 4 must be also subtracted from of the value of the signals of the distance of the second sensor from the support S.

The method also provides to obtain, in correspondence of a roller support S, the value of the signals of the distance of the first sensor from the layer L and the value of the signals of

the distance of the second sensor 4 from the support S, for example by means of elaborations of the arithmetic average of the respective values of said signals calculated during one rotation period of the roller support or its multiple.

A second and simple variant provides that the device is equipped with the first sensor only of the type able to measure the distance from itself to the first faced thereto and orientated as described in the first variant and, for example, of laser type.

The operation of this second variant of the device 1 according to the method of the invention provides :

- in an initial condition, in which the support S is not covered by the layer L, to provide the control means, by means of the first sensor 3, with a signal related to the distance from the first sensor itself to the support S; - in an operational condition in which the support S is covered by the layer L, to provide the control means, by means of the first sensor 3, with signals of the distance of the first sensor from the layer L;

- to memorize by means of the control means a signal value of the distance from the first sensor to the support S; - to subtract, by means of the control means, a value of the signal of the distance between the first sensor and the support S out from a value of the signals of the distance from the first sensor to the layer L in order to obtain the thickness values of the layer L.

Also in this case the method provides to obtain, in correspondence of a roller support S, the at least a value of the signal concerning the distance between the first sensor and the support S by means of an elaboration of the values of said signal calculated on one rotation period of the roller support or its multiple periods, and it provides to obtain the value of the signals of the distance of the first sensor from the layer L by means of elaboration of the values of said signal calculated on one rotation period of the roller support or its multiple. Said elaborations can consist, for example, in arithmetic media or in other algorithms.

Must be observed that the device and the method of the invention are suitable also for various type of supports, for example, consisting of belt conveyors or mobile flat surfaces and the like, and each of the sensors, first second and third, can comprise one or more sensible elements to provide each with one or more signals. Furthermore, the detected signals in the operational condition can be digitized also with relative high sampling frequencies, for example 10 or 100 times bigger than the inverse of the period of the roller rotation, and elaborate in real time.

An advantage of the present invention is to provide a device to measure a thickness of a material, which is almost soiling and error free and is to provide a measuring method and a device avoiding or reducing errors in detecting the thickness caused by irregularity of the layer and/or of the respective support and/or of misalignment.

Further advantage is to provide a wear-free, durable and reliable device, which is also free from errors caused by the vibrations or by environmental agents.