EP1137512B1 - Grinding process control method and computer-aided control for wide grinding machines - Google Patents

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

Technical field

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

State of the art

The technical development has in relation to the process automation in the went through two striking phases in the past decades. In a first euphoric section from about 1970 to 1985 was called CIM (Computer integrated manufacturing) the fully automatic factory without operating personnel postulated. However, very important facts were overlooked. The first fact is that one manufacturing company is very rarely comparable to another. Often a model of a hydroelectric power plant with a subsequent Substation out. With the hydropower plant as with the substation pure potential and flow changes or voltage changes as well as energy conversions performed. The "material" itself, ie water or electricity are not changed and obeyed as flowing "media" with high accuracy known physical laws. In contrast, are in a grinding process corresponding laws are not even known. The second fact recognizes 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 in any case different with the other material. The third factor lies in the fact that, according to current knowledge, the automation of a production process in itself no longer presents any difficulties, except in relation to the neuralgic Area of monitoring and sensor means. Without monitoring and sensor means there is no automation, because otherwise given goals of quantity and quality never are reachable. The big problems are just beginning with the sensor means. So that sensors generate and pass on precise information about the local conditions the sensor technology must be connected to the respective product, i.e. Customized wood, plastic, rubber, cork, plaster and other mineral materials etc. become. Each product requires its own development. In addition, the Technically, people with both the sense of sight and the touch are not achievable meaningfulness, so that the technical replication is very common is worse. The question arises, why automate something and by Technical devices monitor when people do better with their sensors can make? The other question is, what is the customer benefit from one full automation? Practical reality gives the answer and this reads, for example, that specialty areas with a small user group are interested in automation not suitable, unless very special circumstances, such as toxic Problems, risk of explosion, etc., request one. The exaggerated one mentioned at the beginning CIM philosophy came to an end very soon, so that has been around for about 10 years a process automation, the entire circumstances are checked beforehand must, 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 to mean process control or regulation, insofar as it directly influences the goods themselves that are processed or processed is taken. The subject of the present application is Workpieces that are changed using a grinding process. The counterpart to that Process control is the so-called machine control, through which the machine and all modules and components in and on the machine are supplied with power as well as controlled and monitored, with the exception of the workpiece itself Machine control can achieve the highest level of computer technology in terms of expansion contain. Because there is no informational feedback from the workpiece itself, can theoretically the workpiece is almost automatic, but without guarantee for the work result to be edited. So the machine control is blind to the work result, especially for the quality of the result. The process control takes effect in terms of many parameters in the machine control and builds especially on the Machine control on. With a picture is the process control of the vehicle driver, the machine control system the entire vehicle electronics or electronics.

A not unimportant part of the machine control is all safety-related Aspects. An example of this is EP O 127 760. Here is a special construction concept the height setting of a machine upper part of a wide grinding machine trained that e.g. Panels that are too thick do not damage the machine result. The goal is achieved by an infinitely height-adjustable, with an adjustable fluid pressure medium and the upper and lower housing part connected load element, which with a spacer the lowered upper housing part and the lower housing part clamped. Here in the direction of semi-automation, the problem of thickness deviation solved. The applicant is not aware of that in the past 10 or 15 years in practice the next step, namely an automatic process control could be. The inventors have recognized that real customer benefits only really exists if the overall economy increases can be. The overall economy is improved if, firstly, a given one Throughput as well as the required grinding quality and an optimum service life can be achieved are, without additional energy consumption or large and secondly the process and Investment support even without a disproportionate increase in the qualification of the Operating personnel is possible. Investment costs for a computer control can then be kept low if not tailor-made for each individual system an individual control concept must be developed, but if much more a basic concept can be worked out, that for the vast majority of cases in the same area of expertise are successful through mere specific adjustments can be used. With regard to energy consumption, there are serious reasons that at the current usual belt speeds, at least in many cases, the optimum is not achieved. Interestingly enough, in one case it is found that when the belt speed is reduced by approximately 30% not only less stress on the machine, but that the service life of the sanding belt was increased significantly. The task must therefore be solvable if it is possible to select and set optimal parameters for the grinding process.

In the current known state of the art, there is a generic wide grinding machine no process automation. As a result, the new invention represented on the basis of the board production, whereby chipboard is probably the best known Product. A mixture of wood or wood fiber material is used for the production of chipboard and glue pressed into sheets. A full production line for In addition to the storage of raw and finished goods, chipboard mainly consists of Panel production, a sawmill and the grinding line, which is a central part the whole more or less continuous production line. The older one Multi-day board manufacturing processes can only work with a large thickness tolerance getting produced. The heat of the plate presses also results in unwanted Changes to the outermost layer so that experience has shown that which are made according to the old process, 1.2 to 1.8 millimeters from the Plate thickness must be worked away. 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. From Art the quality of the boards, but especially due to the high stock of non-wood materials However, all previous attempts were to grind, for example by planing replace, failed because the wear on the planing knives is too great. This is one of the main reasons why thickness grinding or calibration grinding of Chipboard especially the double-sided grinding of up to 2 mm with grinding machines has prevailed. For this, the so-called wide grinding machines used. Chipboard measure over the width 1 to 3 meters and more, so that Wide grinding machines for a corresponding processing width very stable and must be designed accordingly difficult. The grinding material on the wide grinding machines consists essentially of widths of up to 3 meters Grinding rollers or carrier belts as well as those applied with an adhesive Abrasives. The sanding belts for the wide sanding machines are an endless belt glued. The glue point or the corresponding splice can become independent the type of connection as a so-called chatter mark on the ground plate surface to make noticable. Especially when the ground plate is then covered with a thin foil is coated, no chatter marks may be present. The The grinding process is therefore carried out in several steps: as calibration grinding, as a finishing touch and as a shoe finishing touch. The shoe grinding and the calibration grinding can can be combined as required. The main task is to fine-tune the surface roughness to improve the calibration grinding. The grinding with the grinding shoe serves especially the eradication of the chatter marks. The majority of particle boards are Semi-finished product, on which further surface refinements are then carried out Need to become. For example, chipboard with a thin film coated. For this, the highest demands are placed on the surface quality posed, and also a very high degree of surface flatness, and it becomes a Dimensional accuracy for the plate thickness of ± 1/100 millimeter required. This Claims can only be made with the top and bottom and on both sides of the milling unit acting guide or feed units are guaranteed. The consumption- or wear of abrasives, especially from the quite large abrasive belts in addition to the energy costs, a major factor in the production costs for wide grinding machines. In principle, this statement also applies if instead of Abrasive belts Abrasive rollers are used, even if automatic Resharpenings are made. This is also the maximum for grinding rollers Possible service life depending on the nature of the workpieces to be ground as well as the operating mode. An example of a corresponding wide grinding machine is in GM 94 14 952.6. DE 38 26 706 is based on the older solution according to DE-OS 18 15 858. Die DE-OS 18 15 858 relates to a belt grinding machine for the grinding of plate-shaped Workpieces with a fine grinding unit for a rough grinding unit Achievement of the desired, exact thickness value of the processed plate follows. To the deviations occurring in such grinding machines from the To counteract desired setpoints, the Thickness of the machined workpieces recorded and depending on these thickness measurements controlled a delivery device assigned to the fine grinding unit.

As a solution, an attempt is made to measure the deviation from a predetermined target value first stage, i.e. the rough grinding unit, in the second stage, the fine grinding unit, to correct. DE 38 26 706 evaluates this subsequent correction with the Fine tuning as a disadvantage and had set itself the following task (column 1, middle):

The object of the invention is the pre-trained grinding method in such a way train that deviations from the desired setpoint is counteracted as quickly and particularly effectively, so that even in the event of raw workpieces with large excess thicknesses or strongly fluctuating excess thicknesses at the end of the grinding process, plates with a nominal size are always obtained. The object is achieved in that thickness measurements at least in the area in each case between at least one rough grinding unit and at least one central and / or Fine grinding unit using at least one automatically working Thickness measuring device determined and depending on these thickness measurements at least one infeed device assigned to the rough grinding unit for change the size of the respective grinding gap is controlled.

Through these measures, the Grinding unit or grinding units in the sirine of a percentage Grinding gap opening during the processing of the respective Workpiece always created such a real-time correction that not itself temporarily grinding results that otherwise would have to be accepted in the prior art - to deviate from the required target strength Lead plate thicknesses.

These two known solutions have one correction in common on the faulty one Pieces, based on the actual / target value comparison. The older DE 18 15 858 corrected then in the fine grinding unit. The more recent DE 38 26 706 corrects or controls the corresponding setting in real time on the continuous plate.

Presentation of the invention

The invention was based on the object, according to solutions, especially for one to seek meaningful process control that results in real customer benefit. aim the invention was to provide thickness tolerances and surface quality over extended periods Operating times by changing setting parameters even without manual Ensure intervention. Another equally important sub-goal was, if possible long downtimes of the machine and the equipment (grinding material, etc.) without the to achieve previously mentioned quality losses. This through targeted influence and correction of individual functional elements in a work process for General cargo processing and continuous throughput of the individual workpieces at least two successive loop interventions.

The method according to the invention is characterized in that grinding-related Starting recipes provided, an order-related or work item-specific Optimal start recipe selected and the grinding work or the loop intervention is monitored, and based on the monitoring of the work result of the first and subsequent ground workpieces Reference to at least one or more of the following parameters, as a target or Control variable as necessary, repeated, each for the subsequent workpieces be changed as grinding recipe for follow-up work: grinding acceptance after the first Looping engagement (30); Workpiece thickness, the belt speed of the sanding belt, or the grinding roller speed, the grinding pressure, the throughput speed of the workpiece, quality tolerance band (s) and height intervention for the Grinding procedure.

The computer control according to the invention is characterized in that the Computer control has a process controller that process-related recipes can be selected for the automatic start setting of the loop units, wherein a loop intervention monitoring device is arranged, on the basis of which at Deviation via the grinding recipe, if necessary, repeated corrective interventions are feasible and change the grinding recipe after one or more Continuous test pieces for the follow-up work is made.

• Auswahl von Optimalstartrezept
• Schleifeingriff-Überwacheinrichtung
• sowie die Änderung der Schleifrezeptur nach einem oder mehreren Durchlaufprobestücken für die Folgearbeit
• für die Änderung der Rezeptur werden bevorzugt eine oder mehrere Werkstücke mit einer optimalen Startrezeptur geschliffen und erst nach dem Durchlauf die Änderung vorgenommen.

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 - the new solution is the combination of three key points:

• Selection of optimal start recipe
• Grinding engagement 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 on different Levels can be decided. Preference is already given to the machine or Control system manufacturers specified a basic recipe on which Commissioning can be established. Recipe changes must be limited Extent can be decided directly by the operating personnel, above all, if corrections are required within a batch. However, the recipe must kept under control by the higher management and at least periodically checkable, so that this e.g. influenced by production planning and is decidable. 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 is in the spirit of the entrepreneur with the tools bypasses. The optimal start recipe includes the possibility, e.g. the belt speed to be set so low that the required order for the specific order Grinding quality with sufficient security is still achievable. It should make a distinction 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 it is also conceivable that the equipment will run to the limit under extreme load are required, whereas in the case of only partial utilization of the system, this is done deliberately the equipment can be spared. The obvious consequence is that the service life of the machine, in particular of the abrasives e.g. the sanding belts or grinding rollers are greatly increased and costs can thus be saved. Further the new solution allows a relatively economical management, too if that. Operating personnel make insufficient efforts, or possibly even is unable to intervene economically. With the new solution provides the control itself with optimal setting values so that the maximum possible economy is observed. Another important aspect lies in that the new solution is not limited to a single problem solution. Rather, the new method for controlling the grinding process, or the new one Computer control open in the most important points. It becomes a basic framework provided that figuratively speaking both in depth and in height and width is expandable. The new solution can be used in a variety of operating situations adapt and expand 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, with at least two the following target values can be defined: sanding belt speed or sanding roller speed, Grinding pressure, grinding acceptance, motor power consumption (s), Tolerance ranges of the surface quality as the finish, the grinding quality as the structure of the Surface and thickness dimensions. The target variables are particularly preferred in function of the overall economy, the quality of the end product and the Tool life optimization, especially with regard to the abrasives and the wide grinder and their components selected. The introduction of Different parameters as target sizes has the enormous advantage that important Parameters can be formulated as a wish. Specifically, this means that e.g. target a desired belt speed and engine power consumption as a target are, without compulsory regulation of the machine, so these values really be respected. The priority goal remains e.g. a tolerance band for the plate thickness as well as the surface quality. An important point is not only the direct possibility of intervention of the human being, but above all the recycling, if necessary ongoing registration of sensory control and test results via the human sensory systems. Another important advantage of the new solution is that that in addition to any expansion of the hardware and software for the Control side and also on the machine side and in relation to the sensors etc. none Restriction for additions and further developments as well as networking with other computers exist. One or more drive motors can be speed-controlled trained and e.g. an automatic regulation of the thickness dimension be provided. The thickness measurement can be mechanical, even better via electronic means or via a laser measuring means. For engine power consumption and the grinding pressure can be known components from the trade use. Significant advantages can already be achieved with the four parameters of the new solution. The missing automatically working sensor means can be recorded and monitored by the surveillance personnel as in the prior art the values are entered and saved for later use of the computer control become. Such a procedure allows full automation in stages realize what is mostly the more economical way. A decisive advantage The new solution is that the so-called setting up the machine for one new order is carried out by the process controller or at least supported.

According to a preferred embodiment of the computer control, the height-adjustable ones Grinding units as at least one adjustable calibration unit and at least an adjustable fine grinding unit and the monitoring device as a thickness measuring or thickness monitoring device-trained and after the calibration unit arranged. It is the simplest form of the one described above Wide grinding machine, e.g. for clamping plates. Here comes a particularly important one Aspect of the new solution specifically for wearing. Instead of that due to speculative values a first machine setting is made, will be the same the main grinding work or the calibration grinding was carried out on a sample plate Grinding result after the first grinding intervention or calibration grinding by means of thickness measurement checked. Depending on the result, the following plates are also changed Edited specifications. As far as single plates are concerned, a correction of the Interference parameters during the processing of a plate disadvantageous. The default values should, if there is no damage, keep one plate and one necessary correction can only be used for the subsequent plates. this applies analogously for the third, fourth plate, etc. Depending on the objectives, 2 to 3 Test plates are sufficient until the optimal values for mass processing are determined are. If changes occur during processing, the game starts from front, i.e. one proceeds with the starting recipe as for the first plate. In case of Continuous material must be corrected 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 not the relative one large fluctuations of the raw pressed plate can be measured. After the calibration grinding the final accuracy for the thickness is not yet required. The informative value an exact measurement is best after the calibration grinding, because in consequently not only a guarantee for an exact thickness dimension after the fine sanding exists, but also the best possible surface quality can be achieved. you evaluates the very specific work result on the specific workpiece and can optimize the quality promotion for the subsequent finishing.

It is particularly advantageous to use the process controller as a multi-size controller train with two or more signal inputs of corresponding sensors, in particular sensors for the height adjustment 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 inlet and workpiece outlet and the belt speed (s). The multi-size controller has that Function to monitor several parameters simultaneously and to correct them if necessary. This results in a spatial figure with several boundary walls the number of parameters. The boundary walls can e.g. in extreme cases a stop if there is a risk that an important parameter except Koritroll device, or the immediate implementation of a correction program. It can almost be excluded that several parameters simultaneously have a critical value accept. In practice, either the engine power consumption too large, the grinding acceptance or the surface quality completely outside of one Tolerance value comes to lie. By giving priority to the different A collision can be avoided if there are two parameters at the same time request a correction, which may conflict with one another desire. The corrected values are always for the next plate or the following workpiece. With this method, the parameter that outside of a certain range, a correction is made, the others Parameters remain inactive in the sense of a correction initiative. The starting recipe should be 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 materials such as wood, plastic, rubber, mineral etc. and raw sheet thickness, furthermore at least the basic parameters for the ground product, especially the surface quality as a finish, the grinding quality as a structure, the plate thickness as well Show thickness tolerance. It is also proposed that the starting recipe at least has one or more of the following editing parameters: the height settings the grinding heads or the stand, power consumption of one or more Drive motors, the throughput speed of the workpieces, the belt speed, the life of the sanding belt, or the condition of the sanding belt, the type of sanding belt, Grinding pressure, torque, grinding shoe heating. advantageously, all metrologically recorded parameters as well as the recipe specifications as well as Prescription corrections saved, be it for later evaluation or use. In Great efforts are still required with regard to qualitative surface criteria until these can be monitored using equipment sensors. Here it is now important that surveillance by the human senses as well can be saved and the ratings can be called up again for a later qualitative Human testing. The enormous advantage of registering all important Processing parameters lies in that over time using suitable evaluation methods Laws can be recognized. From that again trend situations can be identified earlier, so that suitable countermeasures can be taken can be taken before damage occurs. It is a matter of a very efficient method based on real practice and to be able to record correlations between the different parameters. It the knowledge of optimal recipes is sufficient, without the knowledge of mathematical Contexts. The automatic process control can be gradually integrated into the Direction of self-learning control. With every repetition an identical grinding job can be done with the last processing obtained optimal recipe values are started.

It is also proposed to use continuous monitoring means, in particular for , Detection of the start of sanding or plate infeed as well as the end of sanding or Plate runout in the case of individual workpieces, or in the case of processing Endless material or butt-to-butt the corresponding sensor signals. The starting formula should have at least two or more thickness tolerance registers, especially for a coarse tolerance and a fine tolerance, furthermore an input option for freely definable tolerance range (s). About the computer means at first plate of a grinding lot a tolerance value on the safe side or the the largest possible, still permissible thickness for the starting recipe can be selected so that this and, if necessary, 2 to 3 following plates with excess thickness in a later one Pass can be reground to the tolerance desired by the customer. Depending on the level of expansion, the system can have a thickness measuring and monitoring device the calibration unit or the first calibration unit and a thickness measuring and Have monitoring device after the last fine grinding unit. In the workpiece feed direction are in the area of the two side edges of the workpieces preferably at least one thickness measuring device or one thickness monitoring device is arranged. Several types of grinding recipes are used in the computer control stored, in particular a) start formulations that can be continuously optimized e.g. due to the last previous same grinding job; b) a test formulation as a starting formulation when processing a new grinding job for the first time; c) grinding recipes, which is optionally based on a previous same grinding job or can be selected based on a starting recipe or a test recipe. The The number of start and grinding recipes depends on the corresponding number different processing orders.

According to another very advantageous design concept, there are basic machining settings Manual input devices provided. These are single, preferably adjustable via corresponding manual actuators. If necessary in the Recipe can be registered. Appropriate manual actuators are at least one or several of the following parameters can be selected: height adjustment of the grinding heads or the machine stand, grinding acceptance of the grinding units, feed of the workpieces, Sanding belt speed, condition of the sanding belt, sanding pressure, torque, Sanding pad warming. This not only has the advantage of being on the move Hand more optimal values can be determined, 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 like the process parameters should be visualized. Either Individual manipulated variables can be corrected manually using the computer keyboard or on site with appropriate feedback to the computer and the visualization. The other changeable parameters in automatic mode are via a if necessary adaptable grinding recipe or corresponding programs can be controlled: via the visualization should the current values in relation to target sizes, on request or in critical situations are automatically displayed: in particular grinding pressure, Grinding acceptance, motor power consumption, thickness and surface tolerances, Sanding belt speed, speed of the workpieces, also pictures from the Schleifstrasse e.g. Loading of the grinding line, stacking, suction, also trend pictures, especially when approaching important target or limit values.

The new solution is primarily based on the model of the classic control. This means that appropriate intervention points the respective values are controlled by the computer as setpoint specifications and remain unchanged until a new control command comes. However, this does not end that individual selected or multiple parameters via subordinate control devices are controllable via corresponding setpoint specifications: Height adjustment the grinding heads or the machine stand, grinding acceptance, workpiece feed, Sanding belt speed, sanding pressure. Such a local regulation can be very be advantageous if better within a certain tolerance band Values are achievable. However, the regulation may only be within the scope and depending on the Computer control or the multi-size controller take place, otherwise the overpredged Objective of overall economy is lost. The classic regulator works according to a strict target / actual value comparison. The multi-size controller takes hold mostly based on completely different criteria. A higher-level parameter can be the Total electricity consumption in peak consumption. It can be interesting at this time be 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. on one Attach the side edge of the plate with a code printer.

Brief description of the invention

die Figur 1

schematisch die Bechnersteuerung des Schleifprozesses;

die Figur 2

ein stark vereinfachtes Beispiel für die Rezepturvorgabe und -korrektur;

die Figur 3

schematische Übersicht der Hauptelemente einer Anlagesteuerung;

die Figur 4a - 4d

Beispiele von Visualisierungen;

die Figur 5

eine automatische Dickenmessung auf beiden Werkstückseiten;

die Figur 6a und 6b

eine Seiten- und Frontansicht einer Dickenmesseinrichtung;

die Figur 7

graphische Darstellung mit zugehörigen Werten der Oberflächenrauhigkeit, über eine Laboruntersuchung;

die Figur 8

Laborbildaufnahme der Plattenoberfläche nach verschiedenen Schleifeingriffen;

die Figur 9a und 9b

eine Front- und Seitenansicht einer Breitschleifmaschine;

die Figur 10

ein Beispiel für den schematischen Aufbau einer vollständigen Maschinen- und Prozess-Steuerung für eine Breitschleifmaschine.

The new solution will now be explained in more detail with the aid of a few exemplary embodiments. Show it:

the figure 1

schematically the cup control of the grinding process;

the figure 2

a very simplified example for the specification and correction of recipes;

the figure 3

schematic overview of the main elements of an investment management system;

the figures 4a - 4d

Examples of visualizations;

the figure 5

an automatic thickness measurement on both sides of the workpiece;

Figures 6a and 6b

a side and front view of a thickness measuring device;

the figure 7

graphic representation with associated values of surface roughness, via a laboratory test;

the figure 8

Laboratory image recording of the plate surface after various loop interventions;

Figures 9a and 9b

a front and side view of a wide grinder;

the figure 10

an example of the schematic structure of a complete machine and process control for a wide grinding machine.

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 ground from above only on one side. The plate 3 has a raw thickness Dr before the grinding engagement, a thickness D _K after the first or calibration grinding and a thickness D _F after the fine grinding. The difference in thickness between Dr and D _K 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 measuring and / or thickness monitoring device 4 is drawn as a loop intervention monitoring device, which is described in greater detail with FIGS. 5, 6a and 6b. The plate thickness D _{K 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 wide grinding machine S _TM , symbolized with a thick line. To simplify matters, H _{P represents} a height position signal generator by means of which the desired grinding acceptance can be determined. The workpiece or the 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 throughput speed of the plate 3 is determined by speed sensors V _PS . In the calibration unit 1, the grinding belt speed V _KBS , the drive motor current A _K and A _F in the fine grinding unit are shown in FIG. In practice, the height position of the abrasives can be done in several ways, as mentioned above over the entire machine stand or, for example, via eccentric adjustment means of each of the grinding heads or on the calibrating 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 control level, which consists of the three primary components: the machine control PLC 12, a recipe memory 13, an order and recipe input 14, and a multi-size controller 15.

Figure 2 is used only to illustrate the recipe control. Are for simplicity only a few parameters are listed. Belt speed as well Height settings are manipulated variables, whereas the decrease in grinding, the thickness and the approximate engine performance are target values, which are not with plate 1 be reached. A recipe correction is made for plate 2, the Recipe correction intervenes in both the manipulated variables and the target variables. It will made a better proposal, so to speak. The actual values of plate 2 are good. In order to is continued with the same recipe specifications for the following plates. Not shown is a tolerance band for the target values grinding decrease l, thickness after l, aproximative engine power l, which is also specified. Arises in relation to the tolerance band is a deviation outside the specified tolerance corrected the prescription again.

Figure 3 shows a schematic representation of a control and management scheme Reason for the new solution. As far as makes sense, the same reference numerals as in the Figure 1 entered. The actual machine control requires many interventions, also for safety reasons, sensor signals such as local temperatures, Motor currents, position signals, e.g. the height positioning of the machine stand or of a single grinding head. At least part of these sensor values are equally important for process control. Especially quality values can can be captured even better and more economically today by people themselves. The The new solution therefore provides that the results of the examination by the human sensors also in the recipe management and for the specifications can be saved. This also includes rapid tests with blue or black chalk, which provides valuable information about the surface, e.g. if so-called chatter marks are available. Man is therefore in the middle of the Set management level, where the administration and monitoring is also located. On Part of the monitoring is the visualization Visu on screens 14 '. With larger ones Today, plants are capturing local situations by cameras, so that events can be followed in different places without direct visual contact can. The visualization has one particularly with the quality monitoring important function. Certain trends can be positive or negative be followed. This can also be done with appropriate program design are automatically displayed if any intervention may be necessary. The visualization allows the operating personnel to intervene earlier than before and change recipes. Especially when it comes to existing systems automate, it can make sense to do this step by step. With STAG is the previous control input 20 denotes. This can remain with the Restriction that commands can also be entered from another place, especially from Multi-size controllers 15 are possible. The concept can also be in a Transitional phase should be provided as a double tax system for emergencies. about a data interface 21 can upstream and downstream investment sectors, for example Panel production, sawmill, transport system etc., for the exchange of information be used. This means that the various investment sectors in the final phase are not only electronically networked, but that overall surveillance anywhere can be provided. It can be used as a whole plate factory Production line can be automatically controlled by the process. During the visualization All important information including the system status can be immediately viewed represent. The visualization image for the entire grinding line is designated by 22. The electrical and electronic connections are from the machine control to the machine parts indicated at 23. 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. With QMs is the possibility of manual entry of values designated especially by quality values.

Figures 4a to 4d show some examples of visualizations. About one Menu tree (Figure 4a) can determine the desired drawing files and immediately on the Screen 14 'are brought for the visualization (Figure 3). From the Machine overview images (FIGS. 4b-4d) show that this 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 the Machine 1 or part of machine 2, each with an independent height adjustment 34 or 35 have. Upstream of machine 1 are feed tables 36, downstream of the machine 2 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 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, passage 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 A _D and the varying dimension Ax using position sensors (not shown) and used accordingly for process control.

FIG. 7 shows three photographs of the respective surface structure after grinding with different abrasive materials or fineness of abrasives P 40, P 100 and P 180. For the characteristic values, Rz means an average roughness depth, RK a core roughness depth and Rpk and Rvk derived values. Analogous are in the FIG. 8 shows corresponding photographic recordings for the roughness.

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 a sanding 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 only show an 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. In terms of the new solution, the speed can preferably be regulated in order to be able to vary the speed of the grinding belts in this way. The width of the machine is indicated with B ^x , which can be from one meter to over three meters.

1. Leitstandebene (für Schleifstrasse):

• Rezepturen
• Anlagezustands-Informationen, Masken, Bilder

2. Bedienebene 1 (im Kontrollraum bei Schleifstrasse):

• Rezeptureri als Eingabe und Verwaltung (nur wenn keine Leitstandebene)
• Rezeptur Abruf wenn Leitstandebene
• Einzeldaten-Eingabe / Steuerung
• Anlagezustands-Informationen (Masken, Bilder)

3. Bedienebene 2 (an Maschine):

• einfache Maschinen-Bedienung, manuell
• Maschinenzustands-Informationen.

FIG. 10 shows the structure of a complete control system including the machine and process control. The process control system includes operation on different levels, as well as visualization and archiving. Conceptually, the following assignments are preferably made to the individual levels.

1st control center level (for Schleifstrasse):

• recipes
• System status information, masks, pictures

2nd operating level 1 (in the control room at Schleifstrasse):

• Recipe as input and administration (only if 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 condition information.

Claims (21)

1. Method for controlling the grinding process of a wide grinding machine for flat workpieces (3) with at least two consecutive height-adjustable grinding interventions, characterised in that grinding process-related starting procedures are prepared, an order-related or workstation-specific optimum starting procedure is selected and the grinding operation or the grinding intervention is monitored, and owing to monitoring of the operation result of the first and subsequent ground workpieces the optimum starting procedure inputs with respect to at least one or more of the following parameters are repeated to the extent required as target or correcting variables and are changed for the respective subsequent workpieces as the grinding procedure for the subsequent operation: grinding reduction after the first grinding intervention (30); thickness of the workpiece, belt speed of the grinding belt, or the grinding roller speed, grinding pressure, throughput speed of the workpiece, quality tolerance band(s) and height intervention for the grinding intervention.
2. Method according to claim 1, characterised in that the control comprises a computer control (12) with a multiple variable controller (15) for target variables, at least two of the following target variables being settable: belt speed, grinding roller speed, grinding pressure, grinding reduction, motor power consumption(s), tolerance ranges for the surface quality as the finish, grinding quality as the structure of the surface and thickness dimensions.
3. Method according to claim 1 or 2, characterised in that the target values can be selected as a function of the overall economic efficiency, in particular the quality of the end product, and optimisation of service life, in particular with respect to the grinding means and the wide grinding machine and the components thereof, and can be corrected if necessary by direct human intervention.
4. Computer control for a wide grinding machine for grinding flat workpieces (3) with at least two consecutive and height-adjustable grinding units, characterised in that the computer control (12) comprises a process controller (15), in that process-related starting procedures can be selected for the automatic starting adjustment of the grinding units (1, 2), a grinding intervention monitoring device being arranged, owing to which, in the event of deviation, correcting interventions can be carried out, optionally repeatedly, via the grinding procedure and the grinding procedure is changed for the subsequent operation according to one or more throughput samples.
5. Computer control according to claim 4, characterised in that at least one adjustable grinding unit is formed as the calibration unit (1).
6. Computer control according to claim 4 or 5, characterised in that at least one adjustable grinding unit (1, 2) and the monitoring device are formed as a thickness measuring or thickness monitoring device (4) and is arranged downstream from the calibration unit (1).
7. Computer control according to any one of claims 4 to 6, characterised in that the process controller (15) is formed as a multiple variable controller and comprises two or more signal inputs of corresponding sensors, in particular of thickness sensors, sensors for the surface structure of the workpieces (3), for the motor power consumption(s), throughput speed of the workpieces, and of workpiece feed and workpiece discharge and belt speed(s) or grinding roller speed, and for quality tolerance, also inputs for such values as are detected by people themselves, such as surface, quality and thickness measurements and for quality tolerance.
8. Computer control according to any one of claims 4 to 7, characterised in that the starting procedure comprises at least the basic information for the crude workpiece (3), the composition of the raw material, for example thickness, hardness, hardness of the surface, layer construction and type of raw material such as wood, plastics material, rubber, mineral etc., and raw plate thickness, also at least the basic parameters for the ground product, in particular the surface quality as finish, the grinding quality as structure, the plate thickness and thickness tolerance.
9. Computer control according to any one of claims 4 to 8, characterised in that the starting procedure comprises at least one or more of the following processing parameters, power consumption of one or more drive motors, throughput speed of the workpieces (3), belt speed, grinding roller speed, grinding belt service life, or grinding belt condition, grinding belt type, grinding pressure, torque, grinding pad heating, cross-grinding.
10. Computer control according to any one of claims 4 to 9, characterised in that it comprises throughput monitoring means (4), in particular for detecting the start of grinding or plate feed and the end of grinding or plate discharge in the case of individual workpieces (3), or the corresponding sensor signals in the case of processing continuous material or piled plates.
11. Computer control according to any one of claims 4 to 10, characterised in that the starting procedure comprises at least two or more thickness tolerance records, in particular for a rough tolerance and a fine tolerance, as well as an input possibility for tolerance band width(s) to be freely defined or changed.
12. Computer control for a wide grinding machine according to claim 11, characterised in that a tolerance value on the secure side, or the largest possible, still permissible thickness for the starting procedure can be selected via the computer means (1 to 2) in the first plate (3) of a grinding station in such a way that these plates (3) with excess thickness can be subsequently ground in a later throughput to the tolerance desired by the customer.
13. Computer control according to any one of claims 4 to 12, characterised in that it comprises a thickness measuring and monitoring device upstream from the calibration unit or the first calibration unit and a thickness measuring and monitoring unit (4) and/or a checking unit for the surface accuracy and structure downstream from the fine grinding unit or after the last fine grinding unit (2).
14. Computer control according to any one of claims 4 to 13, characterised in that it comprises return means for ground plates (3) for a repeat grinding, the return means being able to receive both calibration-ground and finely ground workpieces (3).
15. Computer control according to claim 14, characterised in that a plurality of types of procedures can be stored, in particular

    a) continuously optimisable starting procedures, for example based on the last preceding identical grinding order or initial procedures;

    b) a testing procedure as starting procedure during the first processing of a new grinding order or initial procedures;

    c) grinding procedures which can be selected owing to a preceding identical grinding order or owing to a starting procedure or a test procedure.
16. Computer control according to any one of claims 4 to 15, characterised in that at least one or more respective thickness measuring or thickness monitoring devices (4) are arranged in the workpiece feed direction in the region of the two side edges of the workpieces (3).
17. Computer control according to any one of claims 1 to 16, characterised in that provided for the basic processing adjustments are manual input devices (14) which are individually adjustable, preferably via corresponding manual final control elements, and if necessary can be recorded in the procedure (13), at least one or more of the following parameters being selectable via the corresponding manual final control elements, grinding reduction of the grinding units, feed of the workpieces, grinding belt speed, grinding roller speed, condition of the grinding belt, or of the grinding roller, grinding pressure, torque, grinding pad heating.
18. Computer control according to any one of claims 1 to 17, characterised in that all the important parameters both of the machine parameters and the process parameters can be displayed, individual correcting variables being correctable manually either via the computer input keyboard (20) or on site with corresponding feedback to the computer and the display (22), the remaining changeable parameters in automatic operation being controllable via an optionally adaptable grinding procedure or corresponding programs.
19. Computer control according to any one of claims 1 to 18, characterised in that the instantaneous values with respect to the target variables are shown via the display: in particular grinding pressure, grinding reduction, motor power consumption, thickness and surface tolerances, grinding belt speed, grinding roller speed, throughput speed of the workpieces, also images from the grinding line, for example feeding of the grinding line, unstacking, extraction, also images of trends, in particular when approaching important target or limit values.
20. Computer control according to any one of claims 1 to 19, characterised in that one or more of the following parameters can be controlled via subordinate regulating devices, grinding reduction, workpiece advance, grinding belt speed, grinding pressure.
21. Computer control according to any one of claims 1 to 20, characterised in that in the case of plate-like workpieces (3), a workpiece and quality coding can be applied to a lateral plate edge via a code printer according to the workpiece and grinding parameters.

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