Optimization of cutting processes on machine tools

Abstract

The invention relates to a method for operating a machine tool system (1), comprising a machine tool (5) for machining at least one workpiece (2) using at least one tool (3) and a control device (14) connected to the machine tool (5) for generating a relative movement between the workpiece (2) and the tool (3) according to a program that can be processed by the control device (14), wherein the control device (14) comprises an operating device (15) having a display device (16) for enabling a user (6) to interact with the control device (14). Via the operating device (15), at least one technical parameter can be manually changed by the user (6). The user (6) is usually unaware of how the manually changed technical parameter affects the productivity. Therefore, the invention proposes to determine a measure of the change in a production economic characteristic parameter caused by the change and to display it to the user (6) on the display device (16) directly and / or in relation to the relevant relative measure.

Description

Field of the Invention

[0001] The present invention relates to a method for operating a machine tool system, the machine tool system including a machine tool for machining at least one workpiece by means of at least one tool and a control device connected to the machine tool, the control device being configured to generate a relative movement between the workpiece and the tool according to a program processable by the control device. Background Art

[0002] When machining workpieces, for example, in tool and die making, path programs (CNC-based) are typically used to control the corresponding machine tools, especially milling machines. Path programs (usually also referred to as "subroutines", "CNC programs", "control programs" or simply "programs") are now mainly generated by CAD / CAM / PP systems. Here, the body or object to be produced is first designed using a CAD program (computer-aided design), and then translated into a machine tool-independent code by a CAM program (computer-aided manufacturing), which code describes the machining process. A post-processor (PP) translates the machine tool-independent code into a machine tool-related code, namely a so-called CNC-based path program, which can be used to drive a specific machine tool. Here, the machining is divided into different steps, such as rough machining, pre-finishing and finishing.

[0003] Then the path program created in the CAD / CAM / PP system in the above manner is loaded into the CNC controller of the relevant machine tool provided for machining the workpiece, and then executed on the machine tool by the machine tool user via the CNC controller.

[0004] The path program can be created in a CNC programming language (such as G-code), and is pre-created and not modified any more at the time point processed by the CNC controller. Here, in the path program, especially the machining technology, the tools to be used, the technical parameters (spindle speed, feed rate, cutting speed, etc.), the machine tool functions, the path curve to be followed by the corresponding tool and the corresponding tool directions are pre-determined. The CNC controller usually does not require the values determined in the path program.

[0005] However, the operator of the machine tool can usually freely change the parameters preset by the CNC program by operating the corresponding operating elements on the user interface of the CNC controller. Such technical parameters that may be affected by the machine tool user are especially the cutting speed, feed rate, machining depth or machining width of the tool.

[0006] Here, at the time point when the operator of the machine tool makes a manual intervention in the machining, the operator usually does not know how the specific parameter changes made affect the productivity (the relationship between the added value created by the machining and the resources used).

[0007] From the literature by Mike Lynch: “Monitoring Important Control Panel Functions”, January 17, 2011, page 1-1, XP055733687, some buttons and switches of the CNC machine tool control panel are mentioned, and their functions should be known to the operator of the CNC machine tool. It is stated therein that, for example, changes in feed override or spindle override affect the machining speed and thus the duration required for a given task.

[0008] A system for monitoring and controlling a central facility is known from document US 2017 / 212488 A1. The system includes an advanced optimizer, a sub-facility monitor, a user interface, and a graphical user interface (GUI). The central facility includes a plurality of sub-facilities that are configured to supply thermal energy or act as refrigeration facilities. The duration for filling an energy storage can be determined and displayed through user interaction.

[0009] A control system for a machine tool is known from DE 102009 023648 A1. The machine tool has a working space and a machining unit arranged therein. The control system includes a visualization controller that, based on operating data and a stored machine tool model, shows at least the real machine tool in the real working space of the machine tool on a visualization unit by means of function visualization elements of a virtual machine tool having a virtual machining unit arranged in a virtual working space and of virtual functions of the virtual machine tool. It is designed for simple operability such that an interaction unit is assigned to the visualization unit, which allows manual interaction, and a function data generation unit is provided, which generates corresponding operation data for manual interaction taking into account the assigned functions and transmits the operation data to the visualization controller for displaying, via the visualization elements, the functions preset by manual interaction on the visualization unit.

[0010] A system is known from document US 2019 / 018391 A1, including: one or more computers programmed such that they generate an NC (numerical control) program for manufacturing a workpiece in the case of using a CNC machine tool (computer numerical control) and provide output data for manufacturing the workpiece. The CNC machine tool is configured to execute the NC program to manufacture the workpiece and provide output data, encode instructions of additional computer programs running on the CNC machine tool, and analyze the output data before manufacturing the workpiece according to the instructions of the NC program by the CNC machine tool. In addition, the CNC machine tool selects a data set from the analyzed output data based on one or more predetermined parameters and provides the data set to a computer remote from the CNC machine tool to simplify the machining performed using the CNC machine tool. Here, a warning message or a suggestion for feed override can also be output to the operator.

[0011] From the literature by LOENZO RAG et al., "An object oriented architecture for sensorless cutting force feedback for CNC milling process monitoring and control", ADVANCES IN ENGINEERING SOFTWARE, ELSEVIER SCIENCE, OXFORD, GB, Vol. 41, No. 5, May 1, 2010, pp. 754 - 761, XP026925736, ISSN: 0965 - 9978, DOI: 10.1016 / J.ADVENGSOFT.2009.12.016, a monitoring system for a CNC milling process is known which generates a feedback signal regarding the cutting force. It is proposed to select the cutting speed such that a compromise is achieved thereby between the lowest production cost and the highest productivity.

[0012] From the literature DE 102006 006 273 A1, a system for determining the wear state of a machine tool is known. The system has a machine tool with a controller, a production control computer, a tool database, and a simulation computer, and the simulation computer is connected to the controller of the machine tool, the production control computer, and the tool database respectively via data connections. This is set up to obtain data describing the wear state of the machine tool through a simulation process taking into account the real machine data, manufacturing data, and workpiece data of the machine tool, and to provide the data to a display unit or other processes via the data connections.

[0013] According to the prior art, the optimization based on tool technology is only carried out sequentially during the cutting process. That is, the optimization always depends on the available internal and external experts, and is thus complex in terms of planning and personnel skills.

[0014] In addition, the actual introduction and implementation of newly drafted processes or technologies is highly dependent on the discipline of the employees, and is thus associated with a huge cost for maintenance by the development department (manufacturing technology / industrial engineering).

[0015] The challenge of this situation is based on the fact that there are no characteristic parameters for the people working in the operation area to reflect the effectiveness of their own behavior.

[0016] The cutting process depends on various factors. In particular, the cost of a specific process depends to a large extent on the friction pair (cutting material / material) and the resulting tool wear behavior. For this reason, there is currently no known productivity characteristic parameter that can be used for comparative evaluation. Only the so - called metal removal rate per unit time is repeatedly used to evaluate productivity. SUMMARY OF THE INVENTION

[0017] The object of the present invention is to provide feedback to a machine tool operator on how manual changes made by him to machining parameters on the machine tool affect productivity.

[0018] This object is achieved in a method for operating a machine tool system, the machine tool system comprising a machine tool for machining at least one workpiece by means of at least one tool and a control device connected to the machine tool, the control device being configured to generate a relative movement between the workpiece and the tool according to a program processable by the control device, wherein the control device comprises an operating device having a display device for the interaction of a user with the control device, whereby it is possible that, by means of the operating device, at least one technical parameter is manually changed by the user and, as a result, a measure of the change in the production economic characteristic parameter caused by the change is determined and displayed on the display device directly and / or in relation to a relevant relative measure, wherein the change in the production economic characteristic parameter is determined by the control device and / or an external computing device connectable to the control device, and wherein a tool change time set for tool change, and / or a tool cost required for tool purchase, and / or a machine hour rate determined for operating the machine tool are stored in the control device and / or the external computing device, and wherein the change in the production economic characteristic parameter is determined according to the tool change time and / or the tool cost and / or the machine hour rate.

[0019] Furthermore, this object is achieved by a corresponding machine tool system or a corresponding control device for carrying out such a method.

[0020] A machine tool system for carrying out the method according to the invention comprises at least one machine tool for machining at least one workpiece by means of at least one tool. The machining is preferably a cutting or machining operation, such as a milling operation. However, the present invention is not limited to the latter, and thus also includes machining operations for surface treatment (grinding, polishing, etc.) or additive manufacturing methods (such as 3D printing). Similarly, the term "machine tool" related to the present invention should be interpreted broadly, and thus it is also understood as an additive manufacturing machine or a robot used in machining. The machining itself can relate to a single workpiece. But it can also be a plurality of workpieces, in particular a batch of workpieces, i.e. a series of workpieces machined in the same way.

[0021] A control device (in particular a CNC control device) connected to the machine tool processes a program (also referred to as a subprogram, a path program, a control program, etc.). In particular, the movement path implemented by the tool relative to the workpiece is determined by the program.

[0022] As such, the control device includes an operating device with a display device, and the control device is used for the interaction between the user and the control device, especially for manually setting or changing the parameters of the machining. In particular, with respect to the relevant specifications, the technical parameters (such as spindle speed, feed rate, cutting speed, depth of action or width of action) can be changed through manual interaction. In particular, by rotating the override regulator commonly used in the CNC controller, the feed rate can be directly changed within the range of 0 to 120% of the preset value very simply.

[0023] Generally, the technical parameters are determined by the control program. The technical parameters depend on the machining to be carried out and the specific machine tool set for this purpose. However, the technical parameters can also be at least partially preset by the corresponding machine tool and stored in the controller. This is often the case especially for the spindle speed.

[0024] The present invention proposes that due to at least one manual change of the technical parameters by the operator, a measure of the change caused by this change in the production economic characteristic parameters is determined, in particular a measure of the change in the machining time required for the machining caused by this change and / or a measure of the change in the machining cost caused by the machining and resulting from this change, and is displayed directly and / or with respect to the relevant relative measure on the display device. In particular, the present invention proposes that in order to determine the change in the production economic characteristic parameters, especially the machining time, not only the pure cutting time or the main usage time during which the tool is in contact with the workpiece in particular is detected, but also the auxiliary time, such as the time occurring for tool change, is detected. Therefore, the machining time is the sum of the main usage time and the auxiliary time.

[0025] The change in the machining time is advantageously given in hours, minutes and seconds. However, other forms of indication can also be considered, such as in the form of a bar with a length or height corresponding to the change. It is also feasible to represent it as a percentage with respect to the relative measure.

[0026] Similar to the machining time, a measure related to the change in the machining cost can also be displayed to the operator as a measure of the change in the production economic characteristic parameters caused by this change. These can also be displayed in absolute values, such as in the amount of a specific currency or in the form of a relative measure. Reporting how the parameter change affects the unit cost is a feasible variant of the present invention.

[0027] The relative measure can be generated from the optimal value of the machining to be carried out, but it can also be a value achieved during a previous machining, an average value, etc. This optimal value can in turn be, for example, a theoretical optimal value obtained in a simulation or an optimal value obtained in a comparable actual machining.

[0028] The variation of the machining time is preferably determined based on the service life of the tool, the friction pair, and the time required for tool replacement. The service life of the tool, i.e., the duration during which the tool is in contact (engaged) with the workpiece for machining the workpiece, generally depends on the feed rate, the spindle speed, and the friction pair on the tool side. The friction pair describes which cutting material (i.e., the material of the tool cutting edge) impacts with which material (i.e., the material at the corresponding machined position of the workpiece).

[0029] The variation of the machining cost is preferably achieved based on the machine time cost ("machine hour rate") and the tool cost.

[0030] The advantage provided by the present invention is that the operator of the machine tool can immediately obtain feedback on the impact of his actions on the production economic characteristic parameters, particularly the machining time and / or the machining cost, by manually interacting through the operating device. Thus, the operator immediately receives feedback on the impact of his behavior. In particular, the user can immediately know whether he can achieve the expected effect through his actions.

[0031] For example, if the operator sets the feed rate from 100% to 120% by operating the override regulator, there is often the expectation that the machining will be carried out faster and thus the machining time will be correspondingly reduced. However, with the increase in the feed rate, the tool wear will also increase, and the service life of the tool, i.e., the time during which the tool can perform a predetermined machining within a preset wear limit, will be reduced. Thus, more tools may be required than originally planned to carry out the machining. The resulting additional tool replacement can lead to a reduction in the machining time significantly less than the initial expectation. In the worst case, the machining time (including the auxiliary time) may even increase. The additional tool requirement also has a negative impact on the machining cost caused by the machining. Through the present invention, the operator of the machine tool immediately realizes that the manual intervention he has carried out may not achieve the desired effect. Thus, he can reconsider the manual intervention and, if necessary, not carry out the manual intervention.

[0032] When milling highly labor-intensive workpieces (such as impellers) or mass-producing workpieces, the advantages of the present invention are particularly obvious. Such machining usually results in severe tool wear and thus frequent tool replacement. Since the machining time also includes auxiliary time, such as for tool replacement, this kind of machining requires a long machining time. Therefore, changing the technical parameters of the machine will have a significant impact on the number of tools required, thereby significantly changing the machining time and thus significantly changing the machining cost.

[0033] In the case of such machining-intensive machining, it is particularly important for the operator of the machine tool to immediately obtain feedback on how the manual intervention in the machining affects the production economic characteristic parameters such as the machining time or the machining cost.

[0034] In combination with the present invention, a measure of the change in the corresponding production economic characteristic parameters is advantageously determined by a control device at the machine.

[0035] However, in addition, such calculations can also be made at a computing device external to the control device, such as an edge computer, a CAM system, or in the cloud. Compared to the calculations on the control device, these possibilities offer the advantage that the control device does not have to bear additional computational costs thereby.

[0036] In a preferred embodiment of the present invention, the technical parameters changed manually by the operator are not immediately implemented in the control device. This means that the control device initially continues to operate according to the previously set parameters. Preferably, the change initially only affects the simulation of the machining with the changed parameters. Advantageously, the change in the production economic characteristic parameters is initially also determined only based on the simulation. Thus, before the actual machining change in which the parameter change is actually implemented specifically, the operator can obtain a display of the effect of the parameter change. The parameter change is only implemented when the operator is clear about the influence it causes on a specific machining. This preferably requires the operator to perform a manual interaction with the operating device again, such as pressing a confirmation button. Thereby, parameter changes that negatively affect productivity in an unintentional manner can be prevented in a timely manner.

[0037] In a preferred embodiment of the present invention, the tool change time set for tool change, the tool cost required for tool purchase, or the machine hour rate determined for the operation of the tool is stored in the control device or an external computing device. Advantageously, the measure of the change in the production economic characteristic parameters is then derived based on the tool change time, the tool cost, or the machine hour rate.

[0038] By detecting the tool change time, the tool cost, and the machine hour rate, the variables that have the greatest impact on the machining time or machining cost are incorporated into the calculation of the relevant changes. The changes involved can be determined sufficiently accurately especially based on these variables.

[0039] The corresponding variables can be advantageously set by the operator's interaction with the control device or an external computing device. Thereby, the corresponding variables can be input into the system in a simple manner and kept up-to-date at all times.

[0040] The tool change time required for tool change also depends on a large number of parameters. For example, the tool size, the tool magazine position, or the size of the relevant tool magazine all affect the tool change time. Therefore, it is particularly advantageous if the tool change time is measured during the actual operation of the machine and preferably updated continuously. Thereby, the tool change time is always up-to-date and the update does not require manual intervention by the user.

[0041] Production economic characteristic parameters, in particular machining time or machining cost, or their variations are advantageously determined based on measurement values generated during the operation of the machine tool system. These measurement values particularly relate to the actual service life achieved by the tool during machining or the tool change time actually required for tool replacement.

[0042] According to the invention, the process parameters that can be manually changed by the operator and that show the effect of the manual change to the operator are in particular the feed rate and the spindle speed. According to experience, these two process parameters are most often manually changed by the operator on the machine. Therefore, it is advantageous that, in particular for these process parameters, the effect of the change is presented directly in front of the operator's eyes. However, the invention is not limited to these two process parameters and can also relate to other or additional process parameters.

[0043] For the purposes of the present invention, it is important not only to display the absolute values of the production economic characteristic parameters (such as machining time or machining cost) to the user, because the effect of the operator's manual intervention is not directly obvious to the operator in this way. For the operator, it is more important to know how the relevant production economic characteristic parameters change through their intervention.

[0044] Advantageously, the provided explanations are about relative measures. The relative measure is preferably an optimum value, such as the machining time required for machining or the machining cost caused by machining. The optimum value can be a theoretically optimum value, which is obtained, for example, particularly with the aid of a CAM system during the simulation of the machining process. However, for example, the optimum value can also be the value achieved at a specific machine during previous actual machining. By relating to the relative dimension (especially the optimum dimension), the user immediately recognizes the intensity of the machining that the manual intervention respectively affects or will affect.

[0045] The dependence of the machining duration or the metal removal rate per unit time on the feed rate, the machining depth, and the machining width will be illustrated below by taking the cutting of an impeller chamber as an example.

[0046] Machining is carried out using a specific milling cutter from a specific manufacturer, which is present in the tool magazine of the relevant machine in the required quantity for machining.

[0047] The following provisions and specifications shall apply to the exemplary cutting of the chamber of the impeller using a specific milling cutter:

[0048] Cutting speed v c = 180 m / min

[0049] Diameter d = 66 mm

[0050] Number of teeth Z = 4

[0051] Feed rate v f = 4000 mm / min

[0052] Processing depth a p = 0.7 mm

[0053] Processing width a e = 30 mm

[0054] Tool change time t = 2 min

[0055] Machining volume V = 40000 cm 3

[0056] Now, based on these assumptions, further assume that no tool change is required, and the following variables can be derived:

[0057] Machining length l f = V / (a p + a e ) = 1905 m

[0058] Machining duration d t = l f * 1000 / v f = 476 min

[0059] Metal removal rate per unit time Q = V / d t = 84 cm 3 / min

[0060] The tool change time depends on the corresponding machine, especially the tool magazine and tool changer used. The tool change time can vary strongly depending on the machine tool and can also fluctuate in the case of the same machine. For example, these fluctuations can come from different magazine positions or depend on the corresponding position of the tool relative to the workpiece from which the relevant tool change is performed.

[0061] Assume the following real conditions, especially based on measurement values:

[0062] Service life T = 20 min

[0063] Tool change time t = 2 min

[0064] The following variables can be calculated:

[0065] Number of tool changes A = dt / T = 24

[0066] Basic metal removal rate per unit time Q basis = V / (dt + (t * A))

[0067] = 76 cm 3 / min

[0068] Thus, in a specific example, a (mean) tool change time of 2 minutes and a (mean) service life of 20 minutes result in an actual achievable metal removal rate Q per basic unit time basis of approximately 76 cm 3 / min.

[0069] The following table is intended to illustrate how changes in the parameters feed rate, depth of treatment or width of treatment affect the metal removal rate per unit time or the metal removal rate per basic unit time. Here, the metal removal rate per unit time describes the volume cut per unit time without considering tool changes, while the metal removal rate per basic unit time also takes into account the tool change time. In particular, each parameter change affects the service life of the tool, so that the number of tool changes required can change. Overall, given the above relationships, this results in the metal removal rate per basic unit time shown in the table.

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076] The service life shown in the table can be based on information provided by the tool manufacturer, who provides relevant instructions for specific cutting conditions (feed rate, depth of treatment, width of treatment) and the specific material of the workpiece. However, generally, these values are based on tests performed on a machine with a specific workpiece.

[0077] As shown in the table, changes in the feed rate, depth of treatment or width of treatment result in an increase in the metal removal rate per basic unit time. However, they can also make the situation worse.

[0078] Since the tool life depends in particular on all 3 of the above parameters, it is a challenge for the machine user to set these parameters to an overall optimal value for machining, i.e., the maximum metal removal rate per basic unit time.

[0079] Exemplarily illustrate the impact on the manufacturing cost of the impeller depending on the selected parameter settings. Here, the machining is carried out in a first process P1, in which the metal removal rate Q per basic unit time is 60 cm 3 / min, the machining time is 667 min, and 17 tools are required.

[0080] The optimized second process P2 has a metal removal rate Q per unit time of basis 100 cm 3 / min, a machining time of 400 min, and is carried out with 25 tools.

[0081]

[0082] As shown in the table, in the optimized process P2, a cost savings of 6,817 euros (€) per impeller is achieved compared to the first process P1. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] The present invention will be explained in more detail below with reference to the embodiments. The figures show:

[0084] Figure 1 A machine tool system having a numerically controlled machine tool is shown,

[0085] Figure 2 A display according to the present invention on the display of the operation interface is shown,

[0086] Figure 3 Method steps for performing the method according to the present invention are shown,

[0087] Figure 4 Productivity depending on technical parameters is shown,

[0088] Figure 5 A preferred operating range of the machine tool is shown. DETAILED DESCRIPTION OF THE INVENTION

[0089] Figure 1 A schematic view of a machine tool system in the form of a machining center 1 according to the present invention is shown. The machining center performs 5-axis machining of a workpiece 2 with at least one tool 3. The machine tool 5 includes a column 8 movable along the X-axis and a slide 9 movably mounted on the column along the Y-axis and Z-axis and carrying a spindle 10. The spindle 10 can be driven to rotate about an axis C and is arranged to receive the tool 3. The spindle 10 is also pivotally supported about an axis S, wherein the spindle axis C describes a movement on a conical surface during pivoting. The angle between the spindle axis C and the pivot axis S is 45°, and thus, the cone angle is 90°. With this arrangement, it is possible to allow the spindle 10 to achieve an arbitrary tilt angle between the horizontal and vertical extreme positions.

[0090] The machine tool 5 further includes a slide 11 movable along the Z-axis, the slide 11 carrying a workpiece table 12 which can be driven to rotate about an axis B and is arranged to receive the workpiece 2 and corresponding fixing and clamping members (not shown).

[0091] There is a CNC controller 14 for controlling the machining center 1. The CNC controller 14 executes control functions through real-time processing subroutines, and thereby controls the relative movement between the tool 3 and the workpiece 2 in real time. Here, the controller 14 continuously detects the input data or input signals (“actual values”) of the machine tool 5, and the CNC controller 14 generates output signals in the form of control commands for the drive (not shown) of the machine tool 5 taking into account the actual values.

[0092] In addition, the CNC controller 14 has a real-time kernel NCK (numerical control kernel), a PLC (programmable logic control), and an HMI unit 15 (human-machine interface) as main components. The HMI unit has a display 16 for the operator 6 to operate the machining center 1. The machining center 1 can perform machining processes such as milling, turning, drilling, threading, turn-milling, honing, etc. by cutting and forming with geometrically defined cutting edges, and can also perform machining processes with geometrically undefined cutting edges, such as grinding. In addition, non-cutting machining such as rolling or thread forming can also be performed. Through a series of different machining processes, a desired workpiece shape is generated in the working space 13 of the machine tool 5, where the tool 3 and the workpiece 2 move relative to each other along a programmed path and engage with each other. The tools 3 required for performing the machining processes are stored in the tool magazine 7 and are sequentially replaced into the spindle 10 by means of a tool changer (not shown) according to the machining sequence.

[0093] The shown machining center 1 can perform 5-axis machining, which is achieved, for example, when milling free-form surfaces (such as when milling turbine blades).

[0094] The controller 14 is designed such that the user 6 can manually operate the user interface 15 to change the initially preset technical parameters related to machining. For example, the feed rate can be preset in the subroutine stored in the controller 14 and can be changed by the user 6 operating the override regulator present at the user interface.

[0095] According to the present invention, first, the influence of the change is determined and displayed to the user on the display 16 of the controller 14 in the form of changes in the production economic characteristic parameters.

[0096] Figure 2An example of such a display on the display 16 is shown. In this example, the feed rate is increased from the normal 100% to 120% (icon 20). As can be seen from the view, this change in the feed rate increases the total machining time to approximately 106% (icon 21) and the total machining cost to approximately 119% (icon 22). These initially unexpected effects can be explained, for example, by the fact that in a preset machining, the tool used wears faster due to the increase in the feed rate, which in turn leads to higher tool consumption and more and more frequent tool changes.

[0097] Particularly advantageous is that if a technical parameter is manually changed, in the example the feed rate, it does not immediately affect the currently executed machining, but rather the original value of the technical parameter is first retained for the purpose of performing the control function, and only the change in the production economic characteristic parameter depending on this change is determined in the simulation. Thus, the user can take this feedback into account and, if necessary, not make the change or make it in a different way before any change occurs in the workpiece machining. Thus, for example, the user can be prevented from inadvertently reducing the productivity of the machine by manual intervention. Thus, if the manually performed parameter change actually has an impact on the real machining, in this embodiment, the Figure 2 "confirm" button 23 shown in must first be operated to initiate the change, for example by touching the button 23 on the display 16 designed as a touch display

[0098] Figure 3 An embodiment for performing the method according to the invention is illustrated. In a first method step S1, a specific technical parameter is manually changed by the user through the user's interaction with the control device.

[0099] In a second method step S2, a measure of the change in the production economic characteristic parameter caused by the change performed in step S1 is determined and displayed on the display of the control device.

[0100] In step S3, the user makes a further manual input to confirm the change in the technical parameter implemented in step S1.

[0101] In step S4, when a relative movement occurs between the workpiece and the tool, the changed process parameter is taken into account in the control device.

[0102] Figure 4 Illustrates the production economic characteristic parameter (such as productivity) and some technical parameters (feed rate V f 、cutting speed v c 、processing depth a p or processing width a e) The connection between. The curve K1 (dashed line) is a straight line in this case, illustrating the metal removal rate per unit time for an unrealistic application scenario where no tool change is required. Here, the cutting amount, for example, increases linearly with the feed rate.

[0103] The number of tool changes required for a specific actual machining is shown in the curve K2 (dashed line). Due to wear, as the cutting amount of the engaged tool increases, an excessive amount of tools are required.

[0104] The curve K3 illustrates the productivity considering tool changes related to wear. It can be seen therefrom that as the cutting amount (per unit time) increases, the productivity first increases to an optimal value and then decreases again after the optimal value.

[0105] Figure 5 An exemplary illustration is given regarding the feed rate V f of the preferred range, which is preferably within the range between the value V f 1 and V f 2, and is thus determined such that the productivity P deviates from its maximum value by a predetermined value ΔP to the greatest extent. If the machine is at an operating point outside the preferred operating range defined in this way, the operator of the machine preferably receives additional warning information.

[0106] According to the method proposed herein, the employees involved in the determination process receive process-related business data to support their decision-making process. Although there are still non-linear dependencies in the process as described above, for example, the decisions made in the past are clearly reflected to the employees in terms of their mode of action so that they can make better upcoming decisions.

[0107] The present invention leads to a gradual improvement of the process and generally has great potential in terms of savings, efficiency improvement, and cost status optimization.

[0108] Based on this online process evaluation, it is even possible to optimize and adjust the process according to the current usage situation, for example, by presetting standard values or abstract target values (such as TCO / metal removal rate per basic unit time).

Claims

1. A method for operating a machine tool system (1), the machine tool system comprising a machine tool (5) for machining at least one workpiece (2) by means of at least one tool (3) and a control device (14) connected to the machine tool (5), the control device being configured to generate a relative movement between the workpiece (2) and the tool (3) according to a program processed by the control device (14), wherein: The control device (14) comprises an operating device (15), which has a display device (16) for interaction between a user (6) and the control device (14), characterized in that the user (6) manually changes at least one technical parameter with the aid of the operating device (15), thereby determining a measure of a change in a production economic characteristic parameter caused by the change and displaying it on the display device (16) directly and / or relative to a related relative measure, wherein the change in the production economic characteristic parameter is obtained by the control device (14) and / or an external computing device (17) that can be connected to the control device (14), and wherein a tool change time set for the tool change, and / or a tool cost required for purchasing the tool (3), and / or a machine hour rate determined for operating the machine tool (5) are stored in the control device (14) and / or the external computing device (17), and wherein the change in the production economic characteristic parameter is obtained based on the tool change time and / or the tool cost and / or the machine hour rate.

2. The method according to claim 1, wherein: In order to process one of the workpieces (2) or a batch of the workpieces (2), a plurality of identical tools (3) are required, wherein the tools (3) are replaced successively into the tool receiving portion (10) of the machine tool (5) by means of a tool changing device (7), wherein a manual change of the technical parameters leads to a change in the number of identical tools (3) required, and wherein a change in the production economic characteristic parameter is determined based on the corresponding change in the number of the tools (3) required and the number of tool changes associated with the change in the number.

3. The method according to claim 1 or 2, wherein: After the measure of the change in the production economic characteristic parameter is displayed on the display device (16), further manual interaction of the user (6) with the operating device (15) is first required before the processing of the workpiece (2) is adapted to the changed technical parameters.

4. The method according to claim 1 or 2, wherein: The tool change time and / or the tool costs and / or the machine hourly rate can be adjusted by the user (6) interacting with the control device (14) and / or an external computing device (17).

5. The method according to claim 1 or 2, wherein: The tool change time is measured and continuously updated during actual operation of the machine tool (5).

6. The method according to claim 1 or 2, wherein: A measure of the change in the production economic characteristic parameter is derived from measured values ​​generated during the operation of the machine tool (5).

7. The method according to claim 1 or 2, wherein: The feed rate and / or the spindle speed are manually changed by the user (6).

8. The method according to claim 1 or 2, wherein: The measure of the change in the production economic characteristic parameter is displayed as an absolute value.

9. The method according to claim 1 or 2, wherein: The measure of the change in the production economic characteristic parameter is displayed relative to the optimal value of the relevant production economic characteristic parameter.

10. The method according to claim 1 or 2, wherein: The production economic characteristic parameter is the processing time required for processing or the processing cost generated by processing.

11. A machine tool system (1) comprising a machine tool (5) and a control device (14) for executing the method according to any one of claims 1 to 10. 12 . The machine tool system ( 1 ) according to claim 11 , comprising an external computing device ( 17 ) for determining a measure of the machining time required for machining and / or a measure of the machining costs resulting from machining.

13. A control device (14) for a machine tool system (1) according to claim 11 or 12, the control device being configured to carry out the method according to one of claims 1 to 10.

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