EP1137512A1

EP1137512A1 - Grinding process control method and computer-aided control for wide grinding machines

Info

Publication number: EP1137512A1
Application number: EP99957827A
Authority: EP
Inventors: Peter Busenhart
Original assignee: Steinemann AG
Current assignee: Steinemann Technology AG
Priority date: 1998-12-11
Filing date: 1999-12-10
Publication date: 2001-10-04
Anticipated expiration: 2019-12-10
Also published as: EP1137512B1; WO2000035628A1; AU1544400A; DE19915909A1; ATE238135T1; DE19915909C2; DE59905238D1

Abstract

The invention relates to a novel solution for automating the grinding process of wide grinding machines for flat workpieces based on an optimal starting procedure and a grinding operation monitoring device, wherein the starting procedure is adapted for a second, subsequent workpiece and, if necessary, for a third or fourth workpiece. Automation aims at achieving parameters enhancing economic efficiency while ensuring the required end quality of the workpiece. A multiple variable controller is preferably used with the aim of obtaining optimal operating conditions based on selectable correction procedures. The novel solution makes it possible to start off with optimal values that are based, for instance, on low abrasive belt speed and/or low motor current consumption. Depending on the specific tasks to be performed, service life can be increased and/or energy can be saved thereby improving economic efficiency.

Description

Process for controlling the grinding process and computer control for wide grinding machine

Technical field

The invention relates to a computer control and a method for controlling the grinding process of a wide grinding machine for flat workpieces, with at least two successive, height-adjustable grinding interventions.

State of the art

In terms of process automation, technical development has gone through two striking phases in the past decades. In a first euphoric section from approx. 1 970 - 1 985, the term CIM (Computer Integrated Manufacturing) was used to postulate the fully automatic factory without operating personnel. However, very important facts were overlooked. The first fact is that one manufacturing company is very rarely comparable to another. A hydropower plant with a subsequent substation was often used as a model. In the hydropower plant as well as in the substation, pure potential and flow changes or voltage changes as well as energy conversions are carried out. The "material" itself, ie the water or the electricity are not changed and obey, as flowing "media" with high accuracy known physical laws. In contrast, corresponding laws are not even known in a grinding process. The second fact can be seen from the fact that in principle water is always water and electricity is always electricity. On the other hand, when sanding, the material can be wood, glued boards, plastic, rubber, cork, mineral material, etc. The grinding conditions are different with the other material. The third factor lies in the fact that, according to the current state of knowledge, the automation of a production process in itself no longer presents any difficulties, except in relation to the sensitive area of monitoring and sensor means. There is no automation without monitoring and sensor means, since otherwise given goals of quantity and quality can never be achieved. The big problems are just beginning with the sensor devices. So that sensors generate precise information about the local conditions and sensor technology must first be adapted to the respective product, ie wood, plastic, rubber, cork, plaster and other mineral materials etc. Each product requires its own development. Added to this is the fact that human beings, both with their sense of sight and their sense of touch, are not technically attainable at the moment, so that the technical replication is very often worse. The question arises, why automate something and monitor it with technical devices when humans can do better with their sensor systems? The other question is, what is the customer benefit from full automation? Practical reality gives the answer and this is, for example, that special areas with a small user group are not suitable for automation, unless very special circumstances, such as toxic problems, risk of explosion, etc., require one. The above-mentioned exaggerated CIM philosophy came to an end very soon, so that the entire situation has to be checked in advance about 10 years before process automation, in particular whether a special case is ripe for process automation, so to speak. A technically justifiable solution must first be found.

Process automation is understood as process control or regulation insofar as the goods themselves, which are processed or processed, are directly influenced. The subject of the present application is workpieces that are changed using a grinding process. The counterpart to the process control is the so-called machine control, via which the machine and all assemblies and components in and on the machine are supplied with power, as well as controlled and monitored, with the exception of the workpiece itself. A machine control can contain the highest level of computer technology with regard to the degree of expansion . Because there is no informational feedback from the workpiece itself, the workpiece can theoretically be processed almost automatically, but without guarantee for the work result. The machine control is therefore blind to the work result, especially the quality of the result. The process control intervenes in the machine control with regard to many parameters and is based above all on the machine control. The process control of the vehicle drivers, the machine control the entire vehicle electronics and electronics are shown with a picture.

A not unimportant part of the machine control are all safety-related aspects. An example of this is EP 0 1 27 760. Here, a special construction concept is used to design the height adjustment of a machine upper part of a wide grinding machine in such a way that, for example, plates with too great a thickness do not damage the machine. The goal is achieved by a continuously adjustable, with an adjustable fluid pressure medium which can be acted upon and connected to the upper and lower housing part, which braces a spacer with the lowered upper housing part and the lower housing part. The problem of thickness deviation is solved here in the direction of semi-automation. The applicant is not aware that the next step, namely automatic process control, could be implemented in practice in the past 10 or 15 years. The inventors have recognized that real customer benefit can only really be achieved if the overall economy can be increased. The overall economy is improved if, firstly, a given throughput as well as the required grinding quality and an optimum service life can be achieved, without additional energy consumption or large and secondly, the process and plant support is also possible without a disproportionate increase in the qualifications of the operating personnel. Investment costs for a computer control can be kept low if an individual control concept does not have to be developed for each individual system, but if a much more basic concept can be developed, which for the vast majority of cases in the same area of expertise can be achieved through simple specific adjustments can be used successfully. With regard to energy consumption, there are serious reasons why, at least in many cases, the optimum grinding belt speeds are not being achieved at present in practice. Interestingly, in one case it was found that when the belt speed was reduced by around 30%, not only was the machine less stressed, but the service life of the sanding belt was increased considerably. The task must therefore be solvable if it is possible to select and set optimal parameters for the grinding process.

In the currently known state of the art, there is no process automation in generic wide grinding machines. In the following, the new invention is presented on the basis of the board production, whereby chipboard is probably the best known product. For the production of chipboard, a mixture of wood or wood fiber material and glue is pressed into boards. In addition to the storage of raw and finished goods, a complete production line for chipboard consists primarily of plate production, a sawmill and the grinding line, which is a central part of the entire more or less continuous production line. With the older multi-day board manufacturing process, the boards can only be manufactured with a large thickness tolerance. The heat of the plate presses also results in undesirable changes in the outermost layer, so experience has shown that plates made using the old method have to be worked 1, 2 to 1.8 millimeters away from the plate thickness. For those used for a few years New continuous presses still have an oversize of around 0.5 to 0.6 millimeters. The same part is worked away on both sides of the plate. Due to the nature of the board, but especially due to the high stock of non-wood materials, all previous attempts to replace grinding with planing, for example, failed because the wear on the planing knives is too great. This is one of the main reasons why the thickness grinding or calibration grinding of chipboard has prevailed on both sides of up to 2 mm with grinding machines. The so-called wide grinding machines are used for this. Particle boards measure 1 to 3 meters in width and more, so that wide grinders must be very stable and correspondingly heavy for a corresponding processing width. The sanding material in the wide sanding machines essentially consists of sanding rollers or carrier belts that are up to 3 meters wide and the abrasives applied with an adhesive. The sanding belts for the wide sanding machines are glued into an endless belt. The glue point or the corresponding splice can make itself felt as a so-called chatter mark on the ground plate surface, regardless of the type of connection. Especially if the ground plate is then coated with a thin film, no chatter marks may be present. The grinding process is therefore carried out in several steps: as calibration sanding, as fine sanding and as shoe sanding. The shoe grinding and the calibration grinding can be combined as desired. The main task is to improve the surface roughness of the calibration grinding. The sanding with the sanding pad is primarily used to eradicate the chatter marks. Most of the chipboard is a semi-finished product, on which further surface finishing must then be carried out. For example, chipboard is coated with a thin film. For this, the highest demands are placed on the surface quality, and also a very high degree of surface flatness, and a dimensional accuracy for the plate thickness of ± 1/100 millimeters is required. These requirements can only be met with guide and feed units that act at the top and bottom and on both sides of the grinding unit. The consumption or Wear of abrasives, especially from the rather large abrasive belts, is a major factor in the production costs for wide grinding machines in addition to the energy costs. This statement also applies in principle if grinding rollers are used instead of grinding belts, even if automatic resharpening is carried out. Even with grinding rollers, the maximum possible service life depends on the nature of the workpieces to be ground and the operating mode. An example of a corresponding wide grinding machine is shown in GM 94 14 952.6. Presentation of the invention

The invention was based on the task of looking for solutions, above all for a sensible process control, which gives real customer benefit. The aim of the invention was to ensure thickness tolerances and surface quality over longer operating times by changing setting parameters even without manual intervention. Another equally important sub-goal was to achieve the longest possible downtimes for the machine and the equipment (abrasive material, etc.) without the previously mentioned loss of quality. This through targeted influence and correction of individual functional elements, in a work process for piece goods processing and continuous passage of the individual workpieces through at least two successive loop interventions.

The method according to the invention is characterized in that grinding process-related starting recipes are provided, an order-related or work item-specific optimal starting recipe is selected and the grinding work or the grinding intervention is monitored, the optimum starting recipe specifications being determined on the basis of the monitoring device for the work result of the first and / or subsequent ground workpieces Reference to at least one or more of the following parameters, repeated as required as the target or manipulated variable, for the subsequent workpieces as the grinding recipe are changed: Grinding acceptance after the first grinding intervention, workpiece thickness, the belt speed of the sanding belt, or the sanding roller speed, the sanding pressure, the Throughput speed of the workpiece, as well as height settings for the loop engagement.

The computer control according to the invention is characterized in that the computer control has a process controller, that process-related start recipes can be selected, for the automatic start setting of the grinding units, a loop intervention monitoring device being arranged, on the basis of which, in the event of a deviation, it is possible to intervene repeatedly, preferably via the grinding recipe.

According to the invention, it has been recognized that neither classic process control nor classic process control can solve the task at hand. In the foreground of the new solution is the combination of three key points:

- Selection of optimal start recipe

- Grinding intervention monitoring device

- as well as changing the grinding recipe after one or more continuous test pieces for subsequent work - For changing the recipe, one or more workpieces are preferably ground with an optimal starting recipe and the change is only made after the run. A very important point is that the recipes can be decided at different levels. A base recipe is preferably already specified by the machine or control system manufacturer, which can be used as the basis for commissioning. To a limited extent, recipe changes must be able to be decided directly by the operating personnel, especially if corrections are necessary within a batch. However, the recipe must be kept under control by the higher-level management and be checked at least periodically so that it can be influenced and decided, for example, via production planning. The starting point for the solution according to the invention is not the uneducated machinist who works on mere instructions, but the good specialist who deals with the work equipment in the entrepreneurial sense. The optimal start recipe includes the possibility, for example, to set the belt speed so low that the required grinding quality can still be achieved with sufficient certainty for the specific job. A distinction should be made as to whether the highest surface quality is just good enough, or whether lower quality requirements are sufficient. The same applies to the thickness tolerance. This means that the resources have to be used in a more targeted manner. It is also conceivable that the equipment will be pushed to the limit under extreme load, whereas the equipment can be deliberately spared if the system is only partially used. The obvious consequence is that the service life of the machine, in particular of the abrasives, for example the sanding belts or sanding rollers, is greatly increased and costs can thus be saved. Furthermore, the new solution allows a relatively economical management, even if the operating personnel make insufficient efforts to do so, or may not be able to intervene economically. In the new solution, the control itself provides optimal setting values so that the maximum possible economy is maintained. Another important aspect is that the new solution is not limited to a single problem solution. Rather, the new process for controlling the grinding process or the new computer control is open in the most important points. A basic framework is provided, which, figuratively speaking, can be expanded both in depth and in height and width. The new solution can be adapted to a variety of operating situations and expanded as required.

The new invention also allows a number of particularly advantageous configurations, for which reference is made to claims 2 and 3 and 5 to 21. According to the new method, the control preferably has a computer control with a multi-size controller for target sizes, at least two of the following target values being determinable: sanding belt speed or grinding roller speed, grinding pressure, grinding decrease, motor power consumption (s), tolerance ranges of the surface quality as the finish, the grinding quality as Structure of the surface and thickness dimensions. The target variables are particularly preferably selected as a function of the overall economy, the quality of the end product, and the service life optimization, in particular in relation to the abrasives and the wide-grinding machine and its components. The introduction of different parameters as target values has the enormous advantage that important parameters can be formulated as a wish. Specifically, this means that, for example, a desired belt speed and motor power consumption are targeted as a goal, without the machine being forced to regulate, so that these values are actually adhered to. The priority goal remains, for example, a tolerance band for plate thickness and surface quality. An important point is not only the possibility of direct intervention by humans, but above all the co-utilization and, if necessary, ongoing registration of the sensory control and test results via the human sensors. Another important advantage of the new solution is that in addition to any expansion options for the hardware and software for the control side and also on the machine side, as well as with regard to the sensors, etc., there are no restrictions for additions and further developments as well as networking with other computers. One or more drive motors can be designed to be speed-controllable and, for example, an automatic regulation of the thickness dimension can be provided. The thickness measurement can be carried out by mechanical means, or even better by electronic means, or by means of a laser measuring means. Known commercial components can be used for the motor power consumption and the grinding pressure. Already with the four parameters, essential advantages of the new solution can be used. As in the prior art, the missing automatically working sensor means can be recorded by the monitoring personnel and the values can be entered and saved for later use by the computer control. Such a procedure allows full automation to be implemented in stages, which is mostly the more economical way. A decisive advantage of the new solution is that the so-called machine setup for a new job is carried out or at least supported by the process controller.

According to a preferred embodiment of the computer control, the height-adjustable grinding units are configured as at least one adjustable calibration unit and at least one adjustable fine grinding unit and the monitoring device as a thickness Measuring or thickness monitoring device designed and arranged after the calibration unit. It is the simplest form of the wide grinder described above, eg for chipboard. This is where a particularly important aspect of the new solution comes into play. Instead of a first machine setting being made on the basis of speculative values, the main grinding work or the calibration grinding is carried out immediately on a sample plate, and the grinding result is checked by means of thickness measurement after the first grinding intervention or calibration grinding. Depending on the result, the following plates are processed with changed specifications. As far as single plates are concerned, a correction of the intervention parameters during the processing of a plate is disadvantageous. If there is no damage, the default values should be retained for one plate and a necessary correction should only be used for the subsequent plates. This applies mutatis mutandis to the third, fourth plate, etc. Depending on the objectives, 2 to 3 test plates should suffice until the optimal values for mass processing are determined. If changes occur during processing, the game starts over, ie you proceed with the starting recipe as for the first plate. In the case of continuous material, the correction must be made immediately. The arrangement of the thickness measuring and monitoring device after the calibration grinding or after the first or second calibration unit has the great advantage that the relatively large fluctuations in the raw pressed plate are not measured. After the calibration grinding, the final accuracy for the thickness dimension is not yet required. The meaningfulness of an exact measurement is most optimal after the calibration sanding, because subsequently there is not only a guarantee for an exact thickness dimension after the fine sanding, but also the best possible surface quality can be achieved. You evaluate the very specific work result on the specific workpiece and can optimize the quality promotion for the subsequent finishing.

It is particularly advantageous to design the process controller as a multi-size controller, with two or more signal inputs from corresponding sensors, in particular sensors for the height adjustment of thickness sensors, sensors for the surface properties of the workpieces, for motor power consumption (es), throughput speed of the workpieces, and the Workpiece entry and exit and the belt speed (s). The multi-size controller has the function of monitoring several parameters simultaneously and correcting them if necessary. A spatial figure with several boundary walls corresponds to the number of parameters. The boundary walls can mean, for example in extreme cases, a stop if there is a risk that an important parameter gets out of control, or the immediate implementation of a correction program. It can almost excluded that several parameters take on a critical value at the same time. In practice it is the case that either the motor power consumption is too high, the grinding decrease or the surface quality is completely outside a tolerance value. By treating the various parameters as a priority, a collision case can be avoided if two parameters require a correction at the same time, which may require opposite interventions. The corrected values are always for the next plate or the following workpiece. With this method, the parameter that is outside a certain bandwidth triggers a correction, the other parameters remaining inactive in the sense of a correction initiative. The starting recipe should include at least the basic information for the raw workpiece, the composition of the raw material, e.g. thickness, hardness, hardness of the surface, layer structure and type of raw material such as wood, plastic, rubber, mineral etc. and raw board thickness, as well as at least the basic parameters for the ground product, in particular the surface quality as a finish, the grinding quality as a structure, the board thickness and thickness tolerance. It is also proposed that the starting recipe have at least one or more of the following processing parameters: the height settings of the grinding heads or the stand, power consumption of one or more drive motors, the throughput speed of the workpieces, the belt speed, the grinding belt service life or the grinding belt condition, the grinding belt type, Grinding pressure, torque, grinding shoe heating. Advantageously, all parameters recorded in terms of measurement technology as well as the prescription specifications and prescription corrections are stored, be it for later evaluation or use. With regard to qualitative surface criteria, great efforts are still required until these can be monitored using equipment sensors. It is now important here that the monitoring by the human senses can also be saved and the evaluations can be called up again for a later qualitative examination by humans. The enormous advantage of registering all important processing parameters lies in the fact that, over time, suitable evaluation methods can be used to identify regularities. This in turn enables trend situations to be identified at an early stage so that suitable countermeasures can be taken before damage occurs. It is a very efficient method to be able to record the laws and correlations between the different parameters based on real practice. Knowledge of the optimal recipes is sufficient, without the knowledge of mathematical relationships. The automatic process control can be gradually brought in the direction of a self-learning control. With every repetition An identical grinding job can be started with the optimal recipe values obtained during the last processing.

It is also proposed to use continuous monitoring means, in particular for detecting the start of grinding or plate entry and the end of grinding or plate exit in the case of individual workpieces, or in the case of processing endless material or butt-to-butt the corresponding sensor signals. The starting recipe should have at least two or more thickness tolerance registers, in particular for a coarse tolerance and a fine tolerance, as well as an input option for freely definable tolerance bandwidth (s). With the computer means, a tolerance value on the safe side or the largest possible, still permissible thickness for the starting recipe can be selected for the first plate of a grinding lot, so that these and possibly 2 to 3 subsequent plates with excess thickness are subsequently passed to those of the customer desired tolerance can be reground. Depending on the degree of expansion, the system can have a thickness measuring and monitoring device before the calibration unit or the first calibration unit and a thickness measuring and monitoring device after the last fine grinding unit. At least one thickness measuring or thickness monitoring device is preferably arranged in the area of the two side edges of the work pieces in the workpiece feed direction. Several types of grinding recipes are stored in the computer control, in particular a) start recipes that can be continuously optimized, e.g. based on the last previous same grinding job; b) a test recipe as a starting recipe when processing a new grinding job for the first time; c) Grinding formulations, which can be selected either on the basis of a previous identical grinding order or on the basis of a starting formulation or a test formulation. The number of start and grinding recipes depends on the corresponding number of different processing orders.

According to a further very advantageous design idea, manual input devices are provided for the basic machining settings. These can be set individually, preferably using appropriate manual actuators. Can be registered in the recipe if necessary. At least one or more of the following parameters can be selected via corresponding manual actuators: height adjustment of the grinding heads or the machine stand, grinding removal of the grinding units, feed of the workpieces, grinding belt speed, condition of the grinding belt, grinding pressure, torque, grinding shoe heating. This not only has the advantage that more optimal values can be continuously determined by hand, but that in the event of a malfunction, at least simple grinding work, even without automatism with human Control can be carried out. All important parameters, both the machine parameters and the process parameters should be visualized. Individual manipulated variables can be corrected manually using the computer input keyboard or on site with appropriate feedback to the computer and the visualization. The other changeable parameters in automatic mode can be controlled via an optionally adaptable grinding recipe or corresponding programs. The visualization should automatically display the current values in relation to target sizes, on request or in critical situations: in particular grinding pressure, grinding acceptance, motor power consumption, thickness and surface tolerances, grinding belt speed, throughput speed of the workpieces, as well as pictures from the grinding line, e.g. loading of the Grinding line, stacking, suction, also trend pictures, especially when approaching important target or limit values.

With regard to the individual manipulated variable, the new solution is primarily based on the classic control model. This means that the relevant values are set by the computer as setpoint specifications via corresponding intervention points and remain unchanged until a new control command is received. However, this does not exclude that individual selected or several parameters can be controlled via subordinate control devices via corresponding setpoint specifications: height adjustment of the grinding heads or the machine stand, grinding acceptance, workpiece feed, grinding belt speed, grinding pressure. Such a local regulation can be very advantageous if it can be used to achieve better values within a certain tolerance band. However, the regulation may only be carried out within the framework and depending on the computer control or the multi-size controller, since otherwise the overriding objective of overall economy will be lost. The classic controller works according to a strict setpoint / actual value comparison. The majority of the multi-size controller intervenes according to completely different criteria. A superordinate parameter can be the total power consumption during peak consumption. During this time, it can be interesting to use electricity consumption as the main criterion. The new solution allows a very high degree of automation and the provision of any data. This allows for plate-like workpiece and quality coding e.g. to be attached to a side plate edge with a code printer.

Brief description of the invention

The new solution is now based on some examples with others

Details explained. 1 shows schematically the computer control of the grinding process; FIG. 2 shows a greatly simplified example for prescription specification and correction; FIG. 3 shows a schematic overview of the main elements of an investment control system; FIGS. 4a-4d examples of visualizations; FIG. 5 shows an automatic thickness measurement on both sides of the workpiece; FIGS. 6a and 6b show a side and front view of a thickness measuring device; FIG. 7 graphical representation with associated values of

Surface roughness, via a laboratory test; FIG. 8 laboratory image recording of the plate surface according to various

Loop interventions; Figures 9a and 9b are a front and side view of a wide grinder; 10 shows an example of the schematic structure of a complete

Machine and process control for a wide grinder.

Ways and implementation of the invention

Figure 1 schematically shows the key points of the new solution. A calibration unit 1 and a fine grinding unit 2 are shown. A workpiece 3 is shown as a flat plate 3 that is only ground on one side and ground from above. The plate 3 has a raw thickness Dr before the grinding engagement, a thickness DK after the first or calibration grinding and a thickness DF after the fine grinding. The difference in thickness between Dr and DK is, for example, 0.4 mm, which corresponds to a grinding decrease of 0.4 mm. The grinding decrease in fine sanding is in the range of a few hundredths of a millimeter. After the calibration grinding, a thickness measurement and / or thickness monitoring device 4 is drawn as the loop engagement monitoring device, which is described in greater detail with FIGS. 5, 6a and 6b. The plate thickness DK is determined via two sensing rollers 5 and 6 and the corresponding signal Ds is forwarded via a data bus 7. The calibration unit 1 and the grinding unit 2 are mounted in a stand of the STM wide grinding machine, symbolized by a thick line. To simplify matters, HP represents a height position signal transmitter by means of which the desired grinding acceptance can be determined. The workpiece or plate 3 is guided several times so that the desired grinding accuracy can be achieved at all. Corresponding single or double guide rollers 8, 9 and drive rollers 10, which are mounted in the machine, ensure the precise conveying of the workpieces through the grinding line, according to arrow 11 in FIG. 1 from left to right. The running speed of the plate 3 is determined by speed sensors VPS. In the case of the calibration unit 1, the grinding belt speed VKBS, the drive motor current AK and AF in the fine grinding unit are shown in FIG. The height position of the abrasives can in practice Several types take place, as mentioned above, over the entire machine stand or, for example, by means of eccentric adjustment means from each of the grinding heads or on the calibration grinding head Hks and on the fine grinding head FHs. The signals mentioned can be made available via the data bus 7 to the control and management level, which consists of the three primary components: the machine control PLC 1 2, a recipe memory 1 3, an order and recipe input 14, and a multi-size controller 1 5.

Figure 2 is used only to illustrate the recipe control. To simplify matters, only a few parameters are listed. Belt speed and height adjustment are control variables, whereas the grinding reduction, the thickness and the approximate engine power are target values which cannot be achieved with plate 1. A recipe correction is carried out for plate 2, the recipe correction intervening both in the manipulated variables and in the target variables. A better proposal is made, so to speak. The actual values of plate 2 are good. This will continue with the same recipe specifications for the following plates. Not shown is a tolerance band for the target values grinding decrease I, thickness according to I, approximate engine power I, which is also specified. If there is a deviation outside the specified tolerance in relation to the tolerance band, the prescription specifications are corrected again.

Figure 3 shows a schematic representation of a control and management scheme based on the new solution. To the extent that it makes sense, the same reference numerals as in FIG. 1 are entered. The actual machine control requires sensor signals for many interventions, also for safety reasons, such as local temperatures, motor currents, position signals, eg the height positioning of the machine stand or a single grinding head. At least some of these sensor values are equally important for process control. Today, quality values in particular can be recorded even better and more economically by people themselves. The new solution therefore provides that the results of the test by the human sensors can also be saved in the recipe management and for the specifications. This also includes rapid tests with blue or black chalk, which provide valuable information about the surface, e.g. whether there are so-called chatter marks. The human being is therefore placed in the middle of the control level, where the administration and monitoring are also located. Part of the monitoring is the visualization Visu on screens 14 '. In larger systems, local situations are captured by cameras today, so that events can be followed at different locations without direct visual contact can. The visualization has an important function especially in quality monitoring. Certain trends can be followed, be it positive or negative. These can also be displayed automatically with the appropriate program design, if any interventions may be necessary. The visualization allows the operating personnel to intervene earlier and to change recipes. Especially when it comes to automating existing systems, it can make sense to do this step by step. The previous control input 20 is designated by STAG. This can remain, with the restriction that command inputs can also be made from another location, in particular from the multi-size controller 15. The concept can also be provided in a transition phase as a double control system for emergencies. Upstream and downstream plant sectors, such as panel production, sawmill, transport system, etc., can be used for information exchange via a data interface 21. This means that in the final phase, the various investment sectors are not only electronically networked, but that the overall monitoring can be provided at any point. This means that an entire plate factory can be automatically process-controlled as a production line. With the visualization, all important information including the system status can be displayed immediately. The visualization image for the entire Schieifstrasse is designated by 22. The electrical and electronic connections to the machine parts are indicated by 23 from the machine control. 24 are the data lines to the measuring devices and sensors in the area of the machine. 25 is the controller sensor for the feed (VPs), 27 for the adjustment device for the height positioning of the machine stand, 28 the height positioning of the individual grinding heads and 26 for the motor currents. QMs refer to the possibility of manually entering values, particularly quality values.

Figures 4a to 4d show some examples of visualizations. The desired partial images can be determined via a menu tree (FIG. 4 a) and immediately brought to the screen 14 ′ for visualization (FIG. 3). From the machine overview pictures (FIGS. 4b-4d) it can be seen that it is a grinding line with first calibration grinding 30, second calibration grinding 31, fine grinding 32 and grinding shoe grinding 33. The corresponding grinding heads are part of machine 1 or part of machine 2, each of which has an independent height adjustment 34 or 35. Upstream of machine 1 are feed tables 36, downstream of machine 2 are discharge tables 37 which, together with the grinding machines, represent an entire grinding line. FIGS. 5, 6a and 6b show a thickness measuring and monitoring device 4, FIG. 5, viewed in the transport direction. Four identical measuring heads 40 '... 40 "" are arranged vertically one above the other in pairs on both sides of the workpiece or the plate 3. All measuring heads can be horizontally adjusted to an optimal measuring position on an upper carrier 41 or a lower carrier 42, so that the measuring heads can be arranged inward from the outer edge by a dimension b with respect to a specific plate width B. The two stable supports 41, 42 are connected via supports 43, 43 'and supported downwards. The start, flow and end of a plate can be determined with a further flow sensor 44. The sensing rollers 5 and 6 are pressed onto the workpiece 3 by the measuring heads with a certain force via corresponding pneumatic cylinders. The exact thickness of the workpiece 3 can be continuously determined from the fixed dimension AD and the varying dimension Ax via position sensors (not shown) and used accordingly for the process control.

FIG. 7 shows three recordings of the respective surface structure after sanding with different abrasive material or grain fineness of the abrasives P 40, P 100 and P 1 80. With the characteristic values, Rz means an average roughness depth, RK a core roughness depth and Rpk and Rvk characteristic values derived therefrom. Corresponding photographic recordings for the roughness are correspondingly shown in FIG.

Depending on the area of application, a wide variety of dispositives and combinations with single or double-sided grinding can be selected. Calibration sanding or coarse sanding, fine sanding up to superfinishing with an abrasive brush, furthermore for each single or multiple application, sanding belt and sanding roller etc. can be used. For this purpose, reference is made to the known prior art and also to the GM 94 14 952 cited in the introduction. FIGS. 9a and 9b show only one example of a specific embodiment of a wide grinding machine with two grinding heads 50, 50 'and 51, 51' for grinding workpieces on both sides. The machine consists of an upper stand 52 and a lower stand 53. The height of the upper stand is adjusted via controllable spindles 54. Each grinding head has its own drive motor 55, which in the sense of the new solution can preferably be speed-controlled in order to speed up the Ability to vary sanding belts. The width of the machine is indicated with B ^x , which can be from one meter to over three meters.

Figure 10 shows the structure of a complete control system including the machine and process control. The process control system closes the operator if necessary at different levels, as well as visualization and archiving. Conceptually, the following assignments are preferably made to the individual levels.

1 . Control room level (for grinding line):

- recipes

- System status information, masks, pictures

2.Operation level 1 (in the control room at Schleifstrasse):

- Recipes as input and administration (only if there is no control center level)

- Recipe call when control center level

- Single data entry / control

- System status information (masks, pictures)

3rd operating level 2 (on machine):

- simple machine operation, manual

- Machine status information.

Claims

claims

1. Method for controlling the grinding process of a wide grinding machine for flat workpieces with at least two successive height-adjustable grinding interventions, d ad u rc hgekennzeichn et that grinding process-related start recipes provided, an order-related or work item-specific optimal recipe selected and the grinding work or the grinding intervention is monitored, whereby Due to the monitoring of the work result of the first and subsequent ground workpieces, the optimal starting recipe specifications with respect to at least one or more of the following parameters, as a target or manipulated variable as necessary, are repeated for the subsequent workpieces as a grinding recipe: Grinding acceptance after the first grinding intervention; Workpiece thickness, the belt speed of the sanding belt, or the sanding roller speed, the sanding pressure, the throughput speed of the workpiece, quality tolerance belt (s) as well as vertical engagement for the sanding engagement.

2. The method according to claim 1, d ad u rc hgekenn ze ichn et that the controller has a computer control with a multi-size controller for target sizes, wherein at least two of the following target values can be defined: belt speed, grinding roller speed grinding pressure, grinding decrease, motor power consumption (s), tolerance ranges the surface quality as the finish, the grinding quality as the structure of the surface and thickness dimensions.

3. The method according to claim 1 or 2, d ad u rc hgeken nze et that the target variables can be selected in function of the overall economy, in particular the quality of the end product, and the service life optimization, in particular in relation to the abrasives and the wide-grinding machine and its components, and can be corrected by direct human intervention if necessary.

4.Computer control for wide grinding machine for grinding flat workpieces with at least two successive and height-adjustable grinding units, so that the computer control has a process controller that process-related start recipes can be selected, for automatic start setting of the grinding units, one of which Loop intervention monitoring device is arranged, on the basis of which correction interventions can be carried out repeatedly in the event of a deviation, preferably via the grinding recipe.

5. Computer control according to claim 4, so that at least one adjustable grinding unit is designed as a calibration unit.

6. Computer control according to claim 4 or 5, so that at least one adjustable grinding unit and the monitoring device are designed as a thickness measuring or thickness monitoring device and are arranged after the calibration unit.

7. Computer control according to one of claims 4 to 6, d ad u rc hge ke n nz eichn et that the process controller is designed as a multi-size controller and has two or more signal inputs of corresponding sensors, in particular of thickness sensors, sensors for the surface quality of the workpieces, for the Motor power consumption (s), throughput speed of the workpieces, as well as the workpiece entry and exit and the belt speed (s) or grinding roller speed, and for the quality tolerance, as well as inputs for values that are recorded by humans themselves, such as surface, quality and thickness measurements and for the quality tolerance.

8. Computer control according to one of claims 4 to 7, d ad u rc hge ke n nze i ch net that the starting recipe at least the basic information for the raw workpiece, the composition of the raw material such as thickness, hardness, hardness of the surface, layer structure and type of raw material such as wood, plastic, rubber, mineral etc. and raw board thickness, furthermore at least the basic parameters for the ground product, in particular the surface quality as a finish, the grinding quality as a structure, the board thickness and thickness tolerance.

9. Computer control according to one of claims 4 to 8, d ad u rc hge ke n nz eichn et that the starting recipe has at least one or more of the following processing parameters, power consumption of one or more drive motors, the throughput speed of the workpieces, the belt speed, the grinding roller speed the life of the sanding belt or the condition of the sanding belt, the type of sanding belt, sanding pressure, torque, sanding shoe heating, cross sanding.

10. Computer control according to one of claims 4 to 9, d ad u rc hge ke n nz eichn et that it has continuous monitoring means, in particular for detecting the start of grinding or plate entry and the grinding end or plate exit in the case of individual workpieces, or in the case of a Processing of continuous material or butt-to-butt of plates the corresponding sensor signals.

11. Computer control according to one of claims 4 to 10, so that the starting recipe has at least two or more thickness tolerance registers, in particular for a coarse tolerance and a fine tolerance, furthermore an input option for freely definable or too changing tolerance range (s).

12. Computer control for wide grinding machine according to claim 11, so that a tolerance value on the safe side or the largest possible still permissible thickness for the starting recipe can be selected via the computer means for the first plate of a grinding item that these plates with excess thickness can be regrinded to the tolerance desired by the customer in a later run.

13. Computer control according to one of claims 4 to 12, d ad u rc hg eke n nzei chn et that they have a thickness measuring and monitoring device in front of the calibration unit or the first calibration unit and a thickness measuring and monitoring device and / or a test unit for the Surface accuracy and structure after the fine grinding unit or after the last fine grinding unit.

14. Computer control according to one of claims 4 to 13, d ad u rc h g e ke n nze i c h n et that it has return means for ground plates for a renewed grinding, the return means can take over both calibrated and finely ground workpieces.

15.Computer control according to claim 14, so that several types of recipes can be stored, in particular a) continuously optimized start recipes e.g. based on the last previous same grinding job or start-up recipes; b) a test recipe as a starting recipe when processing a new grinding job for the first time, or start-up recipes; c) Grinding formulations which can be selected on the basis of a previous identical grinding order or on the basis of a starting formulation or a test formulation.

16. Computer control according to one of claims 4 to 15, so that at least one or more thickness measuring or thickness monitoring devices are arranged in the workpiece feed direction in the region of the two side edges of the workpieces.

17. Computer control according to one of claims 1 to 16, indicating that manual input devices are provided for the basic machining settings, which can be set individually, preferably via corresponding manual actuators, and can be registered in the recipe if necessary, whereby via the corresponding manual actuators can be selected at least one or more of the following parameters, grinding removal of the grinding units, feed of the workpieces, grinding belt speed, grinding roller speed, state of the grinding belt, or the grinding roller, grinding pressure, torque, grinding shoe heating.

18. Computer control according to one of claims 1 to 17, d ad u rc hge ke n nze ichn et that all important parameters of both the machine parameters and the process parameters can be visualized, wherein individual manipulated variables can be corrected by hand either using the computer keyboard or on site Appropriate feedback to the computer and the visualization, the other changeable parameters in automatic mode being controllable via an optionally adaptable grinding recipe or corresponding programs.

19. Computer control according to one of claims 1 to 18, so that the instantaneous values are displayed in relation to target sizes via the visualization: in particular grinding pressure, grinding decrease, motor power consumption, thickness and surface tolerances, grinding belt speed, grinding roller speed, Passage speed of the workpieces, also pictures from the grinding line, for example Loading of the grinding line, stacking, suction, further trend pictures, especially when approaching important target or limit values.

20. Computer control according to one of claims 1 to 19, so that one or more of the following parameters can be controlled via subordinate control devices, grinding acceptance, workpiece feed, grinding belt speed, grinding pressure.

21. Computer control according to one of claims 1 to 20, d ad u rc h g e k e n nze i ch n et that in plate-like workpieces according to the workpiece and grinding parameters, a workpiece and quality coding can be attached to a side plate edge using a code printer.