MXPA01005717A - Method of controlling a treatment line - Google Patents

Abstract

The invention relates to a method of controlling a treatment line. According to said method a) a correlation between one or several variable parameters of the chemical and/or physical processes of the treatment line and one or several characteristic values that are characteristic of the success of the treatment is established;rules are derived of this correlation that describe the dependence of the characteristic value or the characteristic values of the variable parameters;the correlation and/or the rules derived therefrom are stored in a control system for the treatment line;b) the one or the several characteristic value(s) is/are measured continuously or discontinuously;c) if said characteristic values deviate from a predetermined standard range of values, the/those variable parameter(s) that is/are most closely correlated with said characteristic value is/are modified in the direction which counteracts the deviation of the characteristic value or the characteristic values from the standard range.

Description

METHOD TO CONTROL A TREATMENT LINE This invention relates to a process for controlling a treatment line, in which a workpiece is treated by chemical and / or physical processes. More particularly, the invention relates to processes in which the surface of the workpiece is modified and / or chemically coated. An example of such application is phosphating and the subsequent painting of metals, more particularly car bodies. There is a large number of industrial processes in which a work piece is treated by chemical and / or physical treatment processes. One objective of such treatment may be the chemical modification of the surface of the workpiece or its coating, for example its paint. A frequent goal of such processes is to provide the desired technical or aesthetic properties to the surfaces of the workpieces. An example of this are processes by which the surface of the workpieces can be protected from corrosion or by which the surface of the workpiece receives a desired, aesthetically appealing appearance. In all these cases, the goal of treating the work pieces by chemical and / or physical processes © s produce certain technical or aesthetic effects. That the desired result is achieved depends on the substrate and the selected parameters of the chemical and / or physical processes. The most precisely that we know which of the selectable parameters influence the desired result and how they do it, the parameters can be adjusted so that the desired result is achieved as safely as possible or that the desired technical and / or aesthetic results of the treatment are as good as possible. In this regard, the various constants that are considered to be characteristic of the intended result are defined. These constants are correlated in different ways with one or more of the parameters of the chemical and / or physical processes by which the desired result is to be achieved. The practical knowledge of which parameters of the chemical and / or physical processes influence the result and in what form they do it for the most part of an empirical nature and has been acquired and improved in series of tests. However, it is by no means guaranteed that all correlations between the parameters of the chemical and / or physical processes and the results achieved by the treatment are now sufficiently well known and that these parameters are adjusted so that the desired result is achieved. the most optimal way possible. Consequently, there is a need to refine the known correlations and find new correlations. There is also a need, in case of deviations from the result obtained and the intended result, to recognize those parameters of the chemical and / or physical processes and be able to vary them in such a way that the deviations of the result obtained from the. The result can be corrected as safely as possible. The present invention relates to a process for controlling a treatment line, in which a work piece is worked by chemical and / or physical processes, characterized in that a) a correlation between one or more variable parameters of the chemical processes and / or physicists of the treatment line and one or more constants that are characteristic of the treatment result are established, from it derive rules that define the dependence of the constant or constants on the variable parameters and the correlation and / or the rules derived from it are stored in a control system for the treatment line, b) the one or more constant characteristics of the treatment result are measured continuously or intermittently; and c) in the case of a deviation of these constants from a certain scale of established values or in the case of a significant tendency of these constants to move makes the limits in the scale of established values, that or those variable parameter (s) of the chemical and / or physical processes of the treatment line that are more closely correlated with this constant are altered in accordance with, the correlation established in step a) and / or the derived rules of the same in that direction that counteracts the deviation of the constant or constants of the scale of established values. In this regard, it is certainly advisable to alter only those parameters of the chemical and / or physical processes of the treatment line that do not adversely affect the other constants that are characteristic of the result. The selected parameters of the chemical and / or physical processes are therefore those whose alteration correlates as closely as possible with the divergent constant and whose alteration does not have a negative effect on other constants. This can be done, for example, by a computer program that operates on the lines of an expert system. The process according to the present invention is preferably carried out in such a way that, in step c), the alteration of the variable parameters of the chemical and / or physical processes of the treatment line occurs automatically without human intervention. or that the control system for the process issues an appropriate recommendation to alter the variable parameters. The first alternative corresponds to fully automatic operation of the treatment line, in the second alternative, the operating personnel receives precise information as to which parameters are they will alter and in what way the result of the process according to the invention The control system for friction in accordance with the present invention is preferably installed so that it is "adaptable" Consequently, the process according to the present invention is preferably initiated in such a way that, during the operation of the line of work The correlation between the variable parameters of the chemical and / or physical processes of the treatment line and one or more constant characteristics of the treatment result, and / or the rules derived from it, are adapted. Consequently, care is taken to ensure, in the first place, that the control system receives continuously or at specific times - information about the values of as many as possible of the parameters of the chemical and / or physical processes of the treatment line. This can be done, for example, by automatically analyzing the chemical processing liquids used during the treatment of the workpieces and the passage of the results of the analyzes to the control system for the process according to the invention. This, of course, can also be done by manual entry. Second, care is taken to ensure that the control system is informed as completely as possible about the result of the chemical and / or physical treatment. that is, it receives information about the values of as many as possible of the constants that are important to the result of the treatment. As much as possible, this is also preferably done automatically, but otherwise by manual data entry . In this way, the system is placed in the position of being able to continuously improve the correlation between the real parameters and the results achieved and, if necessary, find new correlations. The way in which the correlation between the individual variable parameters of the Chemical and / or physical processes of the treatment line and the constants characteristics of the ST treatment result stored in the control system and evaluated are basically not important. For example, the rules derived from the empirically discovered correlation can be expressed in the form of mathematical equations, as imprecise relations ("fuzzy logic") or in the form of model-free algorithms., such as neural networks. The appropriate mathematical equations are. for example, many Lilmeales regression methods or a partial minimum square regression. In a particular embodiment, the process according to the present invention can be carried out in a plant in which a chemical modification and / or coating of the surface of the work piece is carried out. A coating may consist, for example, of a single layer or multiple layer paint structure. The chemical nature of the workpiece is initially not relevant. For example, a workpiece may be made of a natural substantial, such as wood, a plastic, or a ceramic or metal material, eg, a surface plastic whose coating behavior will be improved by chemical and / or physical treatment can be involved. A chemical treatment may consist, for example, of an oxidant attack on the plastic surface. An example of a possible physicochemical process is a plasma treatment. Processes in which the metal surface is chemically modified can be involved, particularly in the case of metal workpieces. In this way, the prevention of corrosion can be improved and / or obtain a desired surface appearance. Examples of these processes They are anodization. Chromation, a treatment using complex fluorides, optionally in combination with organic polymers. an alkaline passivation or phosphating of layer formation of non-layering. After this chemical modification, the metal surface can also be coated, for example by painting or enamel, Depending on the type of metal and the chemical treatment, an additional coating may be unnecessary. In an example embodiment of the process according to the invention. The treatment line is a phosphating plant for the phosphatation of metallic surfaces before painting. In this application, phosphating is preferably carried out as the so-called layer-forming phosphating in the form of zinc phosphating. In the course of this, a layer of only a few micrometers in thickness consisting of crystalline zinc phosphate or phosphates in which metals other than zinc (iron, nickel, manganese ...) are incorporated as cations is formed in the metal surface. These foaming processes are used, for example, in the metal industry, in the manufacture of vehicles and in the white goods industry. In industrial plants of the type used, for example, in the production of cars, the phosphating plant as an integer, in addition to having one or more zones of phosphorus. it generally includes one or more cleaning zones and a zone of activation of previous phosphating and, frequently, a zone of post-passivation after phosphating. As a rule, the intermediate rinse with water is carried out between the individual treatment steps in the different treatment zones. Post-passivation in the post-passivation zone, which in favorable cases can still be omitted, is generally followed by painting. In the manufacture of cars, the first step of painting is - ID normally, electrodeposition, cathodic coating However, the anodic electrophoretic coating can also be used or the first layer of paint can be applied, without the aid of current, by submerging the workpiece in the painting or spray bath by spray application of the paint. For example, layer formation phosphating can be carried out in the foefatacion zone by contacting the metallized surface with an acidic aqueous phosphating solution containing 0-3 g / l zinc ions at 3 to 30 g / l. Ce phosphatic ions In the case of acidic phosphatase solutions having a pH on the scale of about 2 8 to about 3.8, phosphate ions are present largely as free phosphoric acid and as dihydrogen phosphate ions. Zinc contents in the phosphating solution are preferably on a scale from 0 4 to 2 g / l and in particular 0.5 to 1 5 g / 1 which is normal for low zinc processes The weight ratio of the phosphate ions to zinc ions in the phosphination rings can vary within wide limits, as long as it is in the range of 3.7 to 30. A weight ratio of 10 to 20 is par- ticularly preferred. zinc ions and phosphate ions the phosphating bath may contain other components of the typical currently typical of phosphate baths. It is preferable to use phosphate solutions containing additional mono- or divalent metal ions that have been found by the experience that they have a favorable effect on the adhesion to paint and on the protection of the phosphate layers produced in this way against corrosion. Consequently, the phosphating solution also preferably contains one or more of the following cations 0.1 to 4 g / l manganese (II), 0.1 to 2 g / l nickel (II), 0.2 to 2 g / l magnesium? or (II), 0.2 to 2 5 g / l calc (II), 0.002 to 0 2 g / l copper (II). 0.1 to 2 g / l cobalt (II). For example. in addition to zinc ions, the phosphate solution contains 0 1 to 4 g / l manganese ions and 0 002 to 2 g / l copper ions and not more than 0 05 g / l and in particular not more than 0.001 g / l of nickel ions as additional cations. However, if you intend to maintain the technology of trication phosphating baths that, in addition to zinc ions, contain O the 4 g / l of manganese ions and furthermore 0.1 to 2.5 g / l nickel ions can be used in addition to the cations divalent layer formation, phosphating baths usually also contain sodium ions, potassium ions, or ammonium ions to adjust the free acid. In the case of foaming baths that are intended to be suitable for different substrates, It has become common practice to add free fluoride and / or complex in quantities of up to? . 5 g / l of total fluoride, of which up to 300 mg / 1 is free fluoride. In the absence of fluoride, the aluminum content of the bath should not exceed 3 mg / l. In the presence of fluoride, higher Al contents are tolerated through the complex formation that provides the concentration of the Al not in compiejo does not exceed 5 mg The use of fluoride-containing baths, therefore, is advantageous when the surfaces to be phosphated consist at least partially of aluminum or contain aluminum. In such cases, it is favorable not to use fluoride in its entirety, but only free fluoride, preferably in concentrations of 0 to 10 g / l. For the phosphating of zinc surfaces, it is not absolutely essential for the phosphating baths to contain the so-called accelerators. For the phosphating of steel surfaces, however, the phosphating solution must contain one or more accelerators. These accelerators are common in the prior art as components of zinc phosphate baths Accelerators are substances that chemically bind the hydrogen formed as a result of the attack by the acid on the metal surface reducing themselves Oxidation accelerators also have the effect of oxidizing iron (II) ions liberated by the attack on steel surfaces in the trivalent stage so that they can be precipitated with iron (III) phosphate. Examples of suitable accelerators are 0.2 to 2 g / l of sulfonate ions of -n-trobenzene. 0.1 to 10 g / l of hydroxylamine in free or bound form. 0.05 to 2 g / l of ions of m-ni trobenzoate, 0.05 to 2 g / l of p-nor trofenol, 1 to 70 mg / 1 of hydrogen peroxide in free or bound form, 0.01 to 0.2 g / l of nitrite ions. 0.05 to 4 g / l of organic N-oxides. 0.1 to 3 g / l nitroguanidine In addition, nitrate ions in amounts up to 10 g / l can be present as co-accelerators that can have a favorable effect. particularly in the phosphating of steel surfaces. In zinc-coated steel phosphating, however, the phosphating solution preferably contains as little nitrate as possible. The concentration of nitrate of 0.5 g / l preferably should not exceed e because, at higher concentrations of nitrate there is a danger of so-called "porosity", ie, the formation of crater-like, white holes in the phosphate layer . Particularly preferred accelerators with hydrogen peroxide - from the perspective of environmental acceptability - and hydroxylamine - for the technical reasons of simpler formulation of regeneration solutions, However, the use of these two accelerators together is not advisable because hydroxylamine It is broken down by hydrogen peroxide. If the hydrogen peroxide in free or bound form is used as an accelerator, concentrations of 0.005 to 0.2 g / l of hydrogen peroxide are particularly preferred. Hydrogen peroxide can be added as such to the phosphating solution. However, hydrogen peroxide can also be added in bound form as compounds that proportion in hydrogen peroxide as a result of hydrolysis reactions in the phosphating bath. Examples of these compounds are persalts, such as perborates, percarbonates, peroxosulfates or peroxyaisulfates. Other appropriate sources of SD hydrogen peroxide? ionic peroxides, such as alkali metal peroxides Hydroxylamine can be used: as the free base, as a hydroxylamine complex or in the form of hydroxylammonium salts If the hydroxylamine is added to the foaming bath or to a bath concentrate. Phosphating will be present largely as a hydroxylammonium cation due to the acidic nature of these solutions. If hydroxylammonium salt is used, sulphates and phosphates are particularly suitable. In the case of phosphates, the acid salts are preferred in view of their superiority. Solubility Hydroxylamine or compounds thereof are added to the phosphating bath in such amounts that the calculated concentration of the free hydroxy lamma is between 0 1 a and 10 g / l, preferably between 0 2 and 6 g / l and more preferably between 0.3 and 2 g / l The effect of hydroxylamine as an accelerator can be helped by the additional use of chlorate. Other appropriate accelerates are the N-oxides. organic compounds described in detail in German patent application DE-A-197 33 373 6 N-methyl formaldehyde is a particularly preferred organic N-oxide The N-oxides are preferably used in combination with co-accelerators, such as chlorate hydrogen peroxide, m-niX-benzene sulphonate or nitroguanidma. The trogaanidma can also be used as accelerator alone, as described, for example, in DE-A-196 34 685 Other parameters known to the skilled artisan for the control of phosphating baths are the pH // or the free acid content and total acid content generally expressed as a point count The free acid point count means the consumption in ml of 0 1 N sodium hydroxide solution in order to titrate 10 ml of bath solution at a pH of 3 6 Similarly, the point count of Total acid indicates consumption in ml at a pH of 8 2 Free acid values between 0 and 1 5 points and total acid values between about 15 and about 30 points are within the usual technical scale Phosphatation n can be carried out by immersion, spray or spray / dispersion processes. Contact times are on the usual scale of between about 1 and about 4 minutes. The temperature of the phosphide solution is on the scale of about 35 to about 70SC and more particularly on the scale of about 40 to about 60 ° C. Consequently, a large number of physical and chemical parameters can be selected to determine the phosphating result and the protective effect of the subsequently applied paint. The physical parameters are in Particularly the temperature of the phosphating bath and the phosphating time It is also important if the parts to be phosphatized are surfaced in the phosphating solution or sprayed with the phosphating solution or if the two processes are carried out one after the other in order Variable The adjustable chemical parameters are the composition of the phosphat solution tion and the content of free acid and total acid content Accordingly, the parameter or variable parameters can be selected from the temperature of the phosphating solution. the concentration of zinc in the phosphating solution, the content of free acid or total acid content in the phosphating solution, the concentration of one or more accelerators in the phosphating solution, the concentration of different polyvalent metal ions to another zinc in the phosphating solution, the period of which the metal surface is in contact with the phosphating solution and the movement of the phosphating solution relative to the metal surface (bath agitation processes of spraying or immersion, pressure of spraying) However, the result of phosphate, 13 - expressed in constants, it does not only depend on the composition of the phosphating bath or on the physical phosphating parameters, but also on previous or subsequent treatment steps. For example, the composition of a previous phosphating cleaning bath can be of significance to the result of phosphating. The same applies to the activation bath whereby, as a rule, phosphating is immediately preceded. Likewise, treatment with a post-passivation bath after phosphating and before painting can be of significance to constants, such as paint adhesion and corrosion resistance. Pre-phosphating cleaning baths usually contain anionic and / or nonionic surfactants together with alkaline builders in aqueous solution. Activation baths generally contain colloidal titanium phosphates in an aqueous solution of disodium hydrogen phosphate having a pH on the scale of about 8 to about 9. The post-passivation baths based on chromatics or chromic acid. in reactive polymers, such as polyvinyl phenol derivatives substituted with amino. and in complete titanium fluorides and / or zirconium fluorides are known as post-passivation baths containing copperThe effect of this bathing in connection with phosphating depends on its composition, temperature, time of treatment and the type of treatment (sprinkling or immersion). When there are intermediate rinsing steps. especially during the final rinse before the cathodic dip coating, the purity of the final rinse water, expressed by its electrical conductivity, can also be of significance. In the process according to the invention, the correlation of these parameters with the characteristic constants of the treatment result can be determined and used for the control of these treatment steps. Accordingly, one embodiment of the process according to the invention involves selecting the parameter or variable parameters of the temperature and / or composition of one or more cleaning baths before the phosphating zone, of an activation bath before the phosphating zone. and / or of a post-passivation bath after the phosphating zone and / or the period during which these baths are in contact with the metal surface. For the selected example of f Dsfat-ition, there is a number of constants that are characteristic of the treatment result. The constants can be selected, for example, from the layer weight of the phosphate layer, the chemical composition of the rostrate layer. the flow of current through the phosphate layer during cathodic polarization, the thickness of an electrophoretic coating applied after phosphating, the adhesion of a paint applied after phosphating, the surface structure (roughness, ripple, luster, etc.) .) of a paint applied after phosphating and the susceptibility of the workpiece to corrosion after phosphating and painting. Several methods are available for the measurement of these constants. The easiest way to determine the layer weight is to separate the phosphate layer and to weigh a sample metal plate before and after. The layer weight can be determined non-destructively, for example by infrared spectroscopy (characteristic vibrations of the phosphate groups). The chemical composition of the phosphate layer can be determined by conventional analysis, for example, by atomic absorption spectroscopy, after its removal. After proper calibration, the proportion of selected elements in the phosphate layer can also be determined by X-ray fluorescence measurement. The measurement of current flow through the phosphate layer during catholic polarization is a quick way to calculate the corrosion resistance of the phosphate layer. The adhesion of a paint applied after phosphating can be determined by conventional tests, such as Erichsen indentation, the T-bend test or a stone impact test (chipping) in a corrosive environment. Various tests of corrosion capacity are available, including the salt spray test, the alternating cXma test and the external temperature test, usually carried out using metal test plates intentionally damaged by marking. If the constants can not be exterminated online and automatically in the production process and passed to the control system for the process, they have to be determined separately and the results have to be fed manually (locally or at a remote location) to the system. control. At the beginning of the process according to the invention, of course it is necessary to previously establish starting values for the parameters of the chemical and / or physical process. These start values can come from previously determined correlations. However, it is also possible to take starting values which are known from the prior art for the respective treatment process or which are known from experience. The process according to the invention is then used to refine these starting parameters in the course of the process in such a way as to obtain the optimal values for the relevant constantsIn this respect, certain parameters can be previously established to vary only within limits that are to be predetermined. The results of the measurements of one or more constants carried out in step b) and / or the measurements taken in step c) are preferably recorded in a data carrier during the process according to the invention Then they are available for purposes of quality control and to check the correlations with optionally other procedures than those used in the process according to the invention. Registration in an inmate can occur locally, that is, in the place where the process according to the invention is carried out. However, the data can also be transmitted to or fed directly - continuously, periodically or in response to an application - in a remote location that may still be outside the production plant in which the chemical and / or physical process occurs. For example, this remote location may be in the manufacturer's facilities of the treatment solutions used in the process according to the invention. In this way. The manufacturer is regularly updated with information on the production process, for example on the values of the variable parameters of the chemical and / or physical processes of the treatment line, without any need for the personnel to remain on site in the line of In this regard, it is also preferred to provide the limiting values of the parameters, within which variations may be automatically made during the process according to the invention, or the scales of established values obtained from the correlation in step a ) to readjust locally or from a remote location. The process according to the invention has the advantage that the values of the chemical and / or physical parameters of the treatment line are automatically adapted as long as the constants under consideration change, for example after a substrate change. Through the process according to the invention, the values of the parameters are regulated in such a way that they are optimal for the present respective substrate. The manual intervention is not necessary at all for this purpose or it can be restricted to adjusting new limits for the permitted value scales of the individual parameters within whose established value scales can be adjusted by the process according to the invention.

Example The process according to the present invention was tested in a phosphatation line of the type normally used in the manufacture of cars. The bodies are first cleaned in three bathrooms, then activated phosphatan, post-passivate. they print with a cathodically depositable electrophoretic coating and then they are coated with filler and painted. The following constants were selected for the effectiveness of this treatment chain. 1. value of chipping in the VW test (K value: best value, K = 1, worst value, K = 10) 2. paint run-off to DIN 53167 after 30 one-week test cycles with a full paint structure , 3. paint thickness of the complete paint structure, 4. CEC thickness = thickness of the cathodic electrophoretic coating for previously established electrical deposition parameters.

Variable parameters: (values set in parentheses' Cleaning baths and activation bath (--- previous treatment "before phosphating): Bath 1: alkalinity of the first cleaning bath (in mol equivalents, established value: 80 - 110) Bath 2: alkalinity in the second cleaning bath (in mol equivalents, established value 80 - 110) Bath 3: alkalinity of the third cleaning bath (in mol equivalents, set value 175 - 185) Active: conductivity of the activation bath in uS / cnr (as a measure of carried cleaning solution) Parameters of phosphating (including post-passivation).

T.A. : total acid (23-28 points) F.A. : free acid (0.7-1.1 points) Zn: concentration of zinc in the phosphating bath (3.0-3.7 points, corresponding to 1-12 g / l) HAS: concentration of the hydroxylamine sulphate accelerator in the phosphating bath (2-3 5 g / l) Cr (VI): concentration in the post-passivation bath (5.0 - 7.0 g / l) Parameters of the CE bath (cathodic immersion coating): pH: pH With conductivity in the bath CEC in uS / crn2 TSC Total solids content in% by weight (19-20) PBR ratio of pigment binder (0.57) MEQ milliequivalents of acid (45-55) Correlation Chart Previous Treatment Parameter Bathroom 1 Bathroom 2 Bathroom 3 Active Target value Value Runoff Thickness 0.6 0.03 CEC thickness Correlation Chart (continued) CEC Phosphating Parameter T.A. FA. Zn HA CrVI pH With T C PBR ME Target value K value 6.4 Runoff 0.2 0.7 Thickness 59.0 Thickness CEC -9.5 27.9 The correlation chart shows the correlation matrix between chemical parameters and constants investigated in the case of variations in the values of chemical parameters such as occur with time in an industrial automotive phosphating line. The correlation was determined by means of the multineal regression method and meaning evaluation by "anova" (= variation analysis). The regression coefficients of meaning are shown in the Table. In this way, the value is negatively correlated with the concentration of zinc, that is, a high zinc concentration in the phosphating bath results in the desired lower values of the K value. In contrast, the paint runoff correlates in particular with the values for the total acid and for the concentration of the hydroxyl sheet of accelerator in the phosphating bath The total thickness of paint is associated with the zinc content of the phosphating bath and otherwise correlates with the parameters Bath 3 and Active. Unlike the thickness of the total paint structure, the thickness of the CEC layer correlates negatively with the concentration of zinc in the phosphating bath and otherwise with the pH and PBR in the CEC bath.

Claims (12)

1. CLAIMS 1, - A process for controlling a treatment line, in which a work piece is treated by chemical and / or physical processes, characterized in that: a) a correlation between one or more variable parameters of the chemical processes and / or physical of the treatment line and one or more constants that are characteristic of the treatment result is established, from it derives rules that define the dependence of the constant or constants on the variable parameters and the correlation and / or the rules derivatives thereof are stored in a control system for the treatment line, b) the one or more constants that are characteristic of the treatment result are measured continuously or intermittently; and c) in the case of a deviation of these constants from a determined scale of established values or in the case of a significant tendency of these constants to move towards the limits in the scale of established values, that / those variable parameter (s) of the chemical and / or physical processes of the treatment line that are more closely correlated with this constant are altered in accordance with the correlation established in step a) and / or the rules derived from it in that direction that counteracts the deviation of the constant or constants of the scale of established values, the alteration of the variable parameters of the chemical and / or physical processes of the treatment line occurring automatically without human intervention or the control system for the process that issues an appropriate recommendation to alter the variable parameters,
2. 2. A process according to claim 1, character that, during the operation of the treatment line, the correlation between the variable parameters of the chemical and / or physical processes of the treatment line and one or more constant characteristics of the treatment result, and / or the rules derived from the same, adapt.
3. 3. A process according to one or both of claims 1 and 2, characterized in that the rules derived from the correlation between the individual variable parameters of the chemical and / or physical processes of the treatment line and one or more constants The characteristics of the treatment result are expressed in the form of mathematical equations, such as imprecise relationships or model-free algorithms.
4. 4, - A process according to one or more of claims 1 to 3, characterized in that the treatment line is a plant in which D is carried out a chemical modification and / or a coating of the surface of the piece of work.
5. 5. A process according to claim 4, characterized in that the treatment line is a phosphating line for the phosphating of metal surfaces before painting.
6. 6. A process according to claim 5, characterized in that the phosphating line has one or more phosphating zones and one or more of the following treatment zones: D-zone cleaning, activation zone, post-zone. passivation.
7. 7. A process according to one or both of claims 5 and 6, characterized in that, in the phosphating zone, the layer formation phosphating is carried out by contacting the metal surface with a phosphating solution. aqueous acidic containing 0.3 to 3 g / l zinc ions and 3 to 30 g / l of phosphate ions.
8. 8. A process according to one or more of claims 5 to 7, characterized in that the parameter or variable parameters are selected from the temperature of the phosphating solution, the concentration of zinc in the phosphating solution, the pH, the content of free acid or total acid content in the phosphating solution, the concentration of one or more accelerators in the phosphating solution, the concentration of polyvalent metal ions other than zinc in the phosphating solution, the period during which the metal surface is in contact with the phosphating solution and the movement of the phosphating solution relative to the metal surface.
9. 9. - A process according to one or more of claims 5 to 7, characterized in that the parameter or variable parameters are selected from the temperature and / or composition of one or more cleaning baths before the phosphating zone, from a barium of activation before the phosphating zone and / or of a post-passivation bath after the phosphating zone and / or the period during which these baths are in contact with the metal surface.
10. 10. A process according to one or more of claims 5 to 9, characterized in that the one or more constant characteristics of the treatment result are selected from the layer weight of the phosphate layer, the chemical composition of the phosphate layer, the flow of current through the phosphate layer during cathodic polarization, the thickness of the electrophoretic coating applied after phosphating, the adhesion of a paint applied after phosphating, the surface structure of an applied paint after phosphating and the susceptibility of the workpiece to corrosion after phosphating and painting,
11. 11. A process according to one or more of claims 1 to 10. characterized in that the results of the measurements of the one or more constants carried out in step b) and / or the measurements taken in step c) are recorded in a data carrier.
12. 12. A process according to one or more of claims 1 to 10, characterized in that the limit values of the parameters, within which variations can be made automatically during the process, or the scales of established values obtained from the correlation in step a) can be established again locally or from a remote location. BESIDES THE INVENTION The invention relates to a method for controlling a treatment line. In accordance with method a) a correlation between one or several variable parameters of the chemical and / or physical processes of the treatment line and one or several characteristic values that are characteristic of the success of the treatment are established; rules of this correlation are derived that describe the dependence of the characteristic value or the characteristic values of the variable parameters; the correlation and / or the rules derived from it are stored in a control system for the treatment line; b) the one or several characteristic values are measured continuously or discontinuously; c) if the characteristic values deviate from the conventional predetermined scale of values, those variable parameters that are more closely correlated with the characteristic value are modified in the direction that counteracts the deviation of the characteristic value or the characteristic values of the conventional scale.