ES2826648A1 - QUALITY ASSESSMENT PROCEDURE FOR LOTS OF CORK SHEETS (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Procedure for evaluating the quality of batches of cork sheets, which comprises the steps of: estimating an optimal number of images (n) necessary to sample the batch, obtaining a number of sections of cork sheets equal to the optimal number, taking a image of each section of plate; classify each image as pluggable or refuged; express the quality of the lot as an estimated percentage of refuge (R); and calculate a confidence interval like: {IMAGE-01} Where R is the percentage of refuge obtained, n the optimal number of images and Z{al/2} the value of the Student's t distribution for a confidence level α and n degrees of freedom. (Machine-translation by Google Translate, not legally binding)

Description

DESCRIPTION

PROCEDURE FOR ASSESSING THE QUALITY OF LOTS OF SHEETS

CORK

OBJECT OF THE INVENTION

The present invention belongs to the technical field of forestry engineering.

More specifically, the invention relates to the field of non-wood forest products technology and has direct application, for example and without limitation, in the assessment of the productive capacity of cork oak forests and the economic analysis of cork extraction.

An object of this invention is to provide a method for evaluating the quality of batches of cork sheets. For this and as will be explained in more detail below, in the quality evaluation procedure according to the present invention, quality is expressed in relation to a variable that depends on technological aptitude, and a procedure is implemented to estimate it, analyzing the caliber. (or thickness) and the appearance of the cross sections of a randomly selected sample of plates.

The present invention contributes to improving the commercialization process for sheet cork by providing a tool that can be used to facilitate the relationship between the buyer and the seller of batches of cork sheets.

TECHNICAL PROBLEM TO BE SOLVED AND BACKGROUND OF THE INVENTION

Cork is the bark of the cork oak ( Quercus suber L.) and one of its best known uses is the manufacture of bottle stoppers, especially wine bottle stoppers. It can also be used in the manufacture of decorative panels and as a thermal and / or acoustic insulating material.

The plates of the so-called "raw cork" are obtained in an operation known as "uncorking" which consists of detaching the bark of the tree, an operation that is repeated After a period of time that is called "uncorking shift." The most common uncorking shift is 9 - 10 years, although in some regions this may be as long as 16

In the technical field of the manufacture of stoppers, the economic value of a cork sheet is determined, in addition to the market situation, by the so-called “technological aptitude” (also known as commercial category, or, more generically, "quality").

The quality of a sheet or piece of cork depends fundamentally on the quantity and quality of the stoppers and discs that can be obtained from it by simple cutting, which is a function, in turn, of the thickness (or gauge) of the sheet. and its appearance (presence or absence of anomalies). Thus, to evaluate the quality of a sheet or piece of cork, it is usual to examine said sheet and assess the factors listed above. Depending on this assessment, a specific technological aptitude is assigned to him from among a predefined set of possible technological aptitudes, in which each technological aptitude corresponds to a predetermined level of quality.

If the classification of the cork is done before it is processed (in the field), only two different technological aptitudes are usually established that depend on the appearance of the cork: “refugo” (not suitable for the manufacture of stoppers) or “pluggable” (suitable) . On some occasions, thinner plates can be separated within this last category, calling them "thin"

After extraction, the raw cork sheets are transported to the factory, where they are boiled and classified in more detail in a variable number of commercial categories or technological aptitudes (usually between 5 and 9), again depending on the size and the appearance of the same. The boiled and classified cork is called prepared cork, and it is marketed in the form of bales of homogeneous quality.

The marketing of raw cork is very frequently done by batches or batches of plates, which can be hundreds of tons (thousands of plates). The sale of a batch can be done before uncorking (with the cork on the tree) or after (in piles). The unit price of cork (€ / kg) is usually set by agreement between the buyer and the seller, depending on the overall quality of the consignment.

Currently there is no UNE nor ISO standard that refers to a methodology for classifying cork sheets, or for qualifying batches based on their quality. Only the vocabulary standard is available (UNE-ISO 633: 2010), which describes anomalies in cork, but not how they affect quality. At the academic level, there are currently electronic procedures that make it possible to improve the objectivity of the plate classification, without it becoming absolute.

In Spain, the quality of cork sheets is usually estimated using the so-called "cove plans", a service that different public bodies (such as the Junta de Andalucía and the Junta de Extremadura) provide to managers. of the cork plantations The aim of this is to inform the producers and managers of the cork forest of the quality of the cork they produce, promote a more transparent market and facilitate the marketing of cork.

Said cove plans consist of carrying out a sampling with which a series of cork pieces are collected (normally between 70 and 100), of small dimensions (of the order of 10x10 cm - 20 x 20 cm); This sampling can be done before uncorking, in the tree (by sampling plots or sampling routes, which are established according to the production and number of trees in each area), or afterwards (in a pile). Later they are transferred to the laboratory, where they are boiled and classified. The quality of each cork sheet is determined by an expert, based on their experience, and assigning each piece to a technological aptitude based on its caliber and appearance. Each of the entities that carry out samples of this type have predefined the total number of pre-existing technological aptitudes in terms of quality (usually 9), as well as their characteristics and relative value. The quality of the batch is expressed by a quality index (Q), calculated as the average of the relative values of the samples obtained.

The cleat plans described above present, in summary, the following limitations:

- The quality index (Q) obtained by classification in a large number of classes is usually deduced based solely on the experience of the classifier, who must have extensive experience and years of training;

- The samples are obtained in the field, transported, and boiled and evaluated in the laboratory; This sets a minimum time of several days between taking samples and obtaining results; Y

- The number of samples obtained is usually limited. In fact, a two-person team can collect 70-120 samples per day, giving sampling errors of around 15%.

DESCRIPTION OF THE INVENTION

The present invention aims to address the limitations of the prior art and provide an alternative to it, characterized by:

- Use as an index the estimated percentage of refugo, R. This index provides less detailed information than the Q index, but it is simpler, understandable and repetitive. Classification in two categories (pluggable and refugo) requires a much lower level of experience;

- Carry out the classification with raw cork samples, without the need for a laboratory process; Y

- Carry out the classification on cross sections of the raw cork sheets, which allows their digitization and archiving with ease, even directly in the field.

To this end, the present invention has as its object a process for evaluating the quality of batches of cork sheets, characterized in that it comprises the following steps:

a) establish a maximum sampling time;

b) estimate an optimal number (n) of images to sample the batch of cork sheets based on the maximum sampling time and the size of the batch of cork sheets to be evaluated,

c) selecting a number of sections of cork sheets equal to the optimal number (n) of images;

d) obtaining the sections of cork sheets by cutting transversely the corresponding cork sheets;

e) taking an image of each section of cork sheet with an image capture means;

f) classify each image as pluggable or refugo, depending on the thickness and appearance of the cork sheet section;

g) express the quality of the lot as an estimated percentage (R) of refuge; and h) calculate a confidence interval, for a confidence level a prefixed as:

where Res is the estimated refuge percentage, n is the optimal number of images and za / 2 is the value of the Student's t distribution for a confidence level a and n degrees of freedom.

In the evaluation procedure according to the present invention, therefore, only two different technological aptitudes are established: pluggable or refugo and the quality of the batch is expressed as the percentage of refugo R, therefore the quality level of a batch of plates of cork will be greater, the smaller the value of the percentage (R) obtained.

Furthermore, the evaluation procedure according to the present invention is designed to classify, preferably, raw cork batches, whatever their type: in the tree, at the foot of the tree, at the loading dock, in the factory yard.

The process of the invention has, among others, the following advantages:

- allows to contrast the results of the quality evaluation, since it is based on images that are recorded;

- It is based on a technological aptitude that can only adopt two different values (refugo / corkable) widely used in the sector and easily understood by all the agents involved in the cork marketing process;

- The use of said technological aptitude, which can only adopt two different values, is more objective and repetitive than the classification in a high number of classes. The classification criteria are simpler, and it is easier to train people who can classify objectively and repetitively. It is also easier to develop mathematical models that mimic this classification;

- the quality of the batch is expressed by a percentage (R), a variable that is also easily understood. Furthermore, the calculation of the confidence interval for the estimate is simple;

- the procedure can be applied with samples (sets of cork sheet sections) of any size. The effect of the sample size is reflected in the confidence interval. Therefore, the procedure can be applied to qualify a single cork oak with only 10 images (genetic improvement programs, for example) as well as to classify lots or cork oak forests with thousands of cork sheets;

- the procedure for obtaining the sample (image) is much faster than the traditional one, which reduces the cost and increases the sample size, with the consequent improvement in the estimation (decrease in the confidence interval); Y

- it is possible to obtain the quality results of the batch at the same time that the samples are classified. It would be possible to rate a game at the same time as the uncorking is taking place.

In a preferred embodiment of the invention, in step f) of classifying the images of each section of cork sheet as pluggable or refuged, said classification is carried out based on the thickness of the section of cork sheet and, furthermore, on depending on the presence or absence of anomalies in said section of cork sheet.

The classification of images in step f) can be done directly visually or, more preferably, with the help of programmable logic means that decrease the subjectivity of the classification.

Likewise, the image capturing means used in step e) are preferably digital image capturing means. Furthermore, all the images obtained by the image capturing means used in step e) are preferably stored in an electronic device.

Preferably, in step e) before taking the images of the cork sheet sections, on each of said cork sheet sections a graduated ruler, an identification code or both are placed.

The incorporation of a graduated ruler makes it easier and more precise to estimate the thickness of the cork sheet section. On the other hand, the use of an identification code, as its name indicates, makes it possible to more easily identify the sections of cork sheet that are present in each of the images taken in step e) by the image capture means.

DESCRIPTION OF THE FIGURES

To complement the present description and in order to help a better understanding of the technical characteristics of the invention, according to preferred examples of practical embodiments thereof, a set of drawings is attached as an integral part of said description, in which with illustrative and non-limiting character, the following has been represented:

Fig. 1.- Shows a block diagram in which the stages of a method according to the invention are listed; Y

Fig. 2.- Shows an image of a section of cork sheet taken by the image capture means.

DESCRIPTION OF A FORM OF EMBODIMENT OF THE INVENTION

A detailed description of a preferred embodiment of the present invention is provided below with the aid of the attached figures 1 to 2.

Fig. 1. shows a flow chart listing the steps in a process for evaluating the quality of batches of cork sheets according to the present invention.

As can be seen, in said figure, the procedure begins with a stage (a), in which a maximum sampling time is established.

Next, in a stage (b) the optimal number (n) of images (also called sample size) is estimated, as a function of the maximum sampling time and the size of the batch of cork sheets.

Next, in a stage (c), the sampling method is set and as many sections of different cork sheets are selected, as images need to be obtained to sample the batch of cork sheets in the best possible way, which is given by the optimal number (n) of images obtained in the previous stage.

In step (d) the sections of cork sheets are obtained by cutting the corresponding cork sheets transversely.

Subsequently, in step (e), with an image capture means, an image is taken of each section of cork sheet obtained in the previous step (d).

Once all the images of the sheet sections have been taken, in step (f) each of said images is analyzed and the section of cork sheet that appears in it is classified as pluggable or refuged, depending on the thickness and appearance. of the cork sheet section.

In the next stage (g) the quality of the lot is expressed as an estimated percentage (R) of refuge and, finally, in stage (h) the confidence interval of said value (R) is calculated in the manner described above.

In Fig. 2 an image of a cork sheet section (s) taken by the image capture means during the stage is shown. In the image you can see the graduated ruler (t) and the identification code (u).

The present invention is by no means limited to the embodiments disclosed herein. Different possible embodiments of this invention will be apparent to the person skilled in the art in light of the present disclosure. Consequently, the scope of protection of the present invention is defined exclusively by the claims that follow.

Claims (5)

1. Procedure for evaluating the quality of batches of cork sheets, characterized in that it comprises the following stages: - establish (a) a maximum sampling time; - estimate (b) an optimal number (n) of images to sample the batch of cork sheets as a function of the maximum sampling time and the size of the batch of cork sheets to be evaluated, - selecting (c) a number of sections of cork sheets (s) equal to the optimal number (n) of images; - obtain (d) the sections of cork sheets (s) by cutting transversely the corresponding cork sheets; - taking (e) an image of each section of cork sheet (s) with an image capture means; - classify (f) each image as pluggable or refugo, depending on the thickness and appearance of the section of cork sheet (s); - express (g) the quality of the lot as an estimated percentage (R) of refuge; and - express (h) also the confidence interval for a preset confidence level (a), calculating it as:

where R is the estimated percentage of refuges obtained, n the optimal number of images and za / 2 the value of the Student's t distribution for a confidence level a and n degrees of freedom. Method according to any of the preceding claims, in which the image capturing means used in step (e) are digital image capturing means. ll 3. Method according to claim 3, in which the images obtained by the image capturing means in step (e) are stored in an electronic device. 4. Method according to any of the preceding claims, wherein in step (e) before taking the images of the sections of cork sheet (s), each of said sections of cork sheet (s) is placed a graduated ruler (t), an identifying code (u), or both. 5. Method according to any of the preceding claims, wherein in step (f) it is carried out using programmable logic means.