Method of generating parameters applied for machining workpiece performed by machine tool

Abstract

To provide a method for generating parameters applied to machining operations conducted by a machine tool.SOLUTION: A method comprises: a. providing priority values for at least two mutually dependent target values representing the machining performance including accuracy, surface finish, machining time as input data to an extended operator support system (1), where at least one priority value is automatically determined by an automatic tuning unit; b. providing at least one of job attributes including complexity and workpiece weight as input data to the extended operator support system; c. automatically determining cycle parameters, machine parameters and ancillary module parameters as output data of the extended operator support system based on the priority values and the job attributes by the extended operator support system.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for generating parameters to be applied to machining of a workpiece performed by a machine tool, and in particular to an enhanced operator assistance unit for generating parameters to be applied to machining of a workpiece performed by a machine tool.

[0002] Background technology High-performance machine tools require computer numerically controlled (CNC) machine-specific configurations that are adjusted before leaving the factory. However, factory adjustments cannot be optimized for a specific machining process and are instead a compromise between various target values ​​for optimizing the machining process. To overcome this drawback, in some cases, two or more predefined adjustment configurations may be pre-installed by the factory and then activated as needed.

[0003] Another approach may be to make available to the operator the specific tuning parameters to be adjusted. However, machine tools are complex electro-mechanical systems with a wide range of adjustment possibilities. These tuning parameters are usually part of complex control systems that are difficult to interpret, making it very difficult for the end user to select the optimal parameters to reach the machining specifications defined by the user. Furthermore, if the machine tool is not set up correctly, it can cause serious damage to the machine tool.

[0004] Therefore, EP 1 308 810 A discloses a method for assisting an operator in setting optimized machine and cycle parameters for a milling machine. The operator can manually select priority values ​​for at least two interdependent target values ​​that represent machining performance. Furthermore, the operator can select job attributes. Based on these selected information, cycle and machine parameters can be automatically determined to be applied to the CNC of the machine tool. This is achieved by an operator assistance system that maps machine and cycle parameters to the information selected by the operator. Applying this method allows the operator to select parameters that are easy to understand. This has a direct positive impact on the machine and cycle parameters used in the machine tool, thereby optimizing machining quality and machining efficiency.

[0005] Today, machine tools must increasingly provide additional functions beyond basic machining. For example, monitoring systems are integrated into machine tools to monitor the machining process in order to improve part quality, protect the machine, and optimize production efficiency. Therefore, in addition to basic machine parameters and machine cycles, numerous other parameters used for such additional functions must also be determined. Determining these parameters is still a challenging task for the operator. For this reason, there is a desire to expand the functionality of the operator assistance system disclosed in EP 1 308 810 A1.

[0006] Summary of the Invention It is an object of the present invention to provide a method for generating parameters to be applied to machine a workpiece performed by a machine tool that allows for optimizing the machining process. In particular, it is an object of the present invention to provide a simplified method that assists an operator to provide optimized parameters to be applied to the machining.

[0007] According to the invention, these objects are achieved by the features of the independent claims. In addition, further advantageous embodiments emerge from the dependent claims and the description.

[0008] In the present invention, a method for generating parameters to be applied to machining of a workpiece performed by a machine tool comprises the steps of: providing priority values ​​of at least two interdependent target values ​​representing machining performance, including accuracy, surface finish, and machining time, as input data to an enhanced operator assistance system; providing at least one of the job attributes including complexity and workpiece weight as input data to an augmented operator assistance system; and automatically determining cycle parameters, machine parameters, and auxiliary module parameters as output data of the augmented operator assistance system based on the selected priority values ​​and job attributes by the augmented operator assistance system. At least one priority value is automatically determined by the automatic adjustment unit. The machine parameters and cycle parameters are applied to a primary control unit configured to control the movements of different axes to perform the machining, and the auxiliary module parameters are applied to a plurality of auxiliary modules configured to perform operations to assist the machining. The auxiliary control parameters are not applied to the machining itself, but are typically applied to extended functions of the machine tool to extend its sensing, actuation, or computation capabilities that the primary control unit cannot provide. Applying such extended functions can improve safety, machining accuracy, productivity, energy efficiency, and improve machine performance.

[0009] Preferably, the objectives are expanded to include machine protection, manufacturing costs, reliability and energy savings.

[0010] The method of the present invention can be applied to any type of machine tool, such as turning, milling, grinding, laser texture machining or EDM machine tools, additive manufacturing systems, etc.

[0011] Target values ​​are usually interdependent and cannot always be achieved simultaneously. For example, reducing the machining time usually reduces machining accuracy. Operating a machine tool in energy-saving mode almost always increases the machining time. Therefore, the operator must select the priority values ​​of the target values ​​to achieve the best possible compromise between the trade-off parameters for the specific machining task.

[0012] The present invention provides a method for optimizing a machining process by assisting an operator in setting parameters for operations to machine a workpiece. The operator may select priority values ​​for different target values ​​related to the machining specifications. Furthermore, at least one priority can be automatically determined by an auto-tuning module without manual selection by the operator. This improves operator assistance. Furthermore, the automatically determined priority does not depend on the operator's knowledge or experience, thereby enhancing machining performance. The automatic determination of priorities can also be used as a verification. The operator can compare the priority values ​​determined by the operator with the automatically determined values. This avoids operator misjudgments and enhances machining reliability.

[0013] Furthermore, a wide range of target values ​​is available, which allows users more flexibility in setting machining specifications and thus further optimizing the machining process. In particular, the target values ​​include surface finish, machine protection, production costs, and energy savings. Users can benefit from these additional target values ​​in a manner that further protects their machine tools, reduces costs, increases machining efficiency, and improves the sustainability of their machining operations.

[0014] Machine protection is a target value for safety requirements. This includes requirements for protecting machine tool machine elements such as axes and spindles. It also includes requirements for protecting machining tools and workpieces. For example, machine spindle protection provides a safety function against machine overload during machining. Machine parameters can affect the load on machine elements. For example, high cutting forces can cause overload of machine tool axes and potentially damage them. Therefore, if machine protection has a high priority, machine parameters must be selected to prevent machine elements from being overloaded. If machining time is a high priority and machine protection is a low priority, the machine parameters determined can be more aggressive to enable fast machining and take into account the risk of damaging machine elements or machining tools.

[0015] Production costs are directed towards the costs required to machine a workpiece, such as the cost of the machining tools, the cost of the workpiece material, and the amortization of the machine tools.

[0016] Quite often, customers want the machining to continue without interruption, so machining reliability can also be a target.

[0017] Energy saving is becoming more and more important for production. Therefore, by adding energy saving as a target, customers can optimize their energy consumption. Certainly, this factor also influences production costs. However, it also influences the sustainability of production, which can be a requirement for machine users.

[0018] In addition to the target values, job attributes are used to further optimize the adjustment of machine parameters, machine cycles, and auxiliary control parameters. Job attributes can be, for example, the weight or mass inertia of the workpiece, or the complexity of the contour.

[0019] In a preferred variant, the method comprises providing machining step information as input data to the enhanced operator assistance system, in particular the machining step information comprising roughing, semi-finishing and finishing.

[0020] Different machining steps may require different machine parameters, cycle parameters, and / or auxiliary parameters. Furthermore, the method of the present invention allows the operator to select different machining steps. In this way, machine tuning can be optimized for different machining steps.

[0021] By applying the method of the present invention, machine parameters can be automatically determined. The machine parameters are settings used by a primary control unit to adjust the dynamic behavior and configuration of the machine. The primary control unit includes a numerical control device (NC) installed in the machine tool. The primary control unit may further include a programmable logic controller (PLC) installed in the machine tool. The NC is mainly responsible for controlling the movement of the axes, while the PLC is mainly responsible for controlling peripheral devices of the machine tool, such as the coolant, doors, tool changer, and workpiece changer.

[0022] Examples of machine parameters are path tolerances that define the maximum deviation of an actual profile from a nominal profile, the minimum feed rate for contouring, the cutoff frequency of a recommended position filter, etc. These machine parameters and their interactions and dependencies are often difficult for machine tool operators to understand. Therefore, the method of the preferred embodiment replaces the difficult task of setting and optimizing machine parameters with a more user-friendly means by selecting priority values ​​for a relatively small set of target values ​​that represent fundamental machine performance and machining characteristics. The automatically determined machine parameters can then be applied to the primary control unit of the machine tool.

[0023] The machine parameters are determined automatically by mapping the selected priority values ​​to the machine parameters using a database, which stores the best configurations of the machine parameters for a given priority of the target values. These predefined values ​​of the machine parameters may be determined by previous tests, experience, or expert knowledge. Other possibilities for obtaining the best possible configuration of the machine parameters for a given selection of priority values ​​of the target values ​​are by interpolation of known configurations of the machine parameters, by explicitly calculating the machine parameters based on a model representing the physical properties of the machine tool, or by some kind of learning procedure based on previous machining parameters and on a feedback loop from measurements of the actual machining parameters.

[0024] One preferred way to implement such a database is to store a table containing predefined values ​​of machine parameters for all possible priority selections.

[0025] Furthermore, the application of the method of the present invention allows for automatic determination of cycle parameters. Modern machine tools have a series of so-called machine cycles. A machine cycle is a predefined procedure executed by the primary control unit to achieve a specific effect. A typical example of such a machine cycle is a dwell at the programmed spindle speed for temperature adjustment after a tool change. Therefore, to make the most of the machine tool's capabilities, specific automatic cycles are executed according to the priority of the target values. This means that, based on the selected priority value, the method automatically determines whether a specific machine cycle is activated or deactivated.

[0026] In particular, by applying the method of the present invention, auxiliary module parameters can be automatically determined. Recently, to further optimize the machining process, multiple so-called auxiliary modules and sensing devices have been integrated or combined with machine tools to assist in machining. Such auxiliary machine modules are controlled by an auxiliary control unit, not by the primary control unit. The auxiliary control unit is implemented externally to the primary control unit but can communicate with the primary control unit and / or the sensing unit. The auxiliary modules provide functions to help improve the machining results, for example, improving accuracy or improving protection of the machine tool, workpiece, and machining tools. The auxiliary modules can provide a series of extended functions, such as machining process monitoring, collision protection, and active vibration control. In particular, the auxiliary modules can also provide functions to compensate for errors caused by thermal effects, thermal error compensation, geometric error compensation, and geometric accuracy limitations, such as table load compensation. The auxiliary modules are not machine cycles.

[0027] The method of the present invention can automatically determine auxiliary module parameters to be applied to the auxiliary module. The auxiliary module parameters are different from machine parameters and cycle parameters. The machine parameters and cycle parameters are parameters essential to machining and must be provided to the primary control unit to enable the machine tool to perform machining. The auxiliary module parameters are applied to auxiliary modules that provide support functions for machining. The auxiliary modules are configured to enhance the basic capabilities of the machine tool.

[0028] In one variant, the auxiliary module is a machining process monitoring module configured to detail diagnostics of the currently running machining process. Preferably, this module is configured to notify a user of critical situations, determine what action to take in response to the critical situation, and initiate the action. This module provides the advantage of preventing damage to the machine tool, the workpiece, and the cutting tool.

[0029] For example, the process monitoring module is intended to function as a protection system. The diagnostics and strategies determined by the machining process monitoring module depend on the components the user wants to protect first. Thus, in addition to weighting between accuracy, surface finish, and machining time, the user can also specify emphasis on, for example, tool protection, machine element protection, or part protection. This is achieved by including tool protection, machine element protection, or part protection in the target values.

[0030] Furthermore, the severity of the situation may vary depending on the machining steps, including roughing, semi-finishing, and finishing, as well as the user's priorities regarding accuracy, surface finish, and machining time. For example, vibrations remaining in the surface finish during roughing operations typically do not adversely affect the quality of the final part, but can be significant if they occur during finishing, as such vibration marks may need to be removed by costly manual polishing. Therefore, the auxiliary module parameters that determine the identification of critical situations and the strategies to address them depend on the machining type and priority values ​​and can be determined automatically by the extended operator assistance unit.

[0031] In another variant, the auxiliary module is configured to enhance thermal error compensation. The auxiliary parameters applied to this module are those parameters that affect the thermal behavior and / or thermal compensation of the machine. For example, a high priority value for accuracy in finishing operations typically requires a lower spindle torque, which means that the power of the spindle motor needs to be throttled to ensure less heat generation and higher machining accuracy. Furthermore, the coolant conditions can be limited and the duration of the warm-up phase adapted to enable more accurate compensation. Therefore, the extended operator assistance unit determines auxiliary parameters such as thermal compensation parameters.

[0032] Furthermore, the auxiliary module configured for thermal error compensation is configured to also receive temperatures at various positions of the machine tool measured by temperature sensors as sensing units, and also receive displacements of the machine tool, such as the axial extension of the spindle, as input information, to perform thermal compensation.

[0033] In one embodiment, the auxiliary module is applied to table load compensation, which is configured to adapt the machine kinematic model to compensate for the structural deviation caused by the heavy parts.

[0034] The enhanced operator assistance system is configured to determine machine kinematic parameters as auxiliary module parameters based on job attribute values ​​selected by an operator or determined automatically.

[0035] The machine kinematic model is stored in the primary control unit. The auxiliary module is configured to determine the weight on the work platform based on information received from a sensing unit, such as a force sensor or a force / torque generated by an axis. This information is sent from the auxiliary module to an automatic adjustment unit, which automatically determines job attributes and sends them to the extended operator assistance system. Based on the priority value and the job attributes, the extended operator assistance system is configured to determine parameters to be applied to the kinematic model. These parameters are first sent to the auxiliary module and then further provided to the primary control unit to compensate for structural deviations.

[0036] The auxiliary module is configured to receive the forces / torques generated by the axes to automatically determine the weight and moment of inertia of the machine table with the part loaded. The sensing unit can provide information about the table load to the auxiliary module, for example, by using strain gauges and piezoelectric ceramic sensing elements. Based on the inputs provided by the auxiliary module and the sensing unit, the auto-tuning unit can automatically determine job attributes, such as the weight of the part, without the operator having to manually select this job attribute.

[0037] In one variant, the auxiliary module is applied to collision detection: it is configured to identify the geometry of the tool and the workpiece clamped in the machining area, create a geometric model and prevent collisions by predicting the risk of collision, for example by analyzing programmed axis displacements.

[0038] In another variant, an auxiliary module is applied for geometric error compensation.

[0039] Preferably, the step of automatically determining the auxiliary module parameters includes mapping the selected priority values ​​to the auxiliary module parameters using a database or structured file system, in which the best configurations of the auxiliary module parameters for a given priority of the target values ​​are stored. These predefined values ​​of the auxiliary module parameters may be determined by previous tests, experience, or expert knowledge. Other possibilities for obtaining the best possible configuration of the auxiliary module parameters for a given selection of priority values ​​of the target values ​​are by interpolation of known configurations of the auxiliary module parameters, by explicitly calculating the auxiliary module parameters based on a model representing the physics of the machine tool, or by some kind of learning procedure based on previous auxiliary control parameters and on a feedback loop from measurements of the actual auxiliary module parameters.

[0040] One preferred way to implement such a database is to store a table containing predefined values ​​of auxiliary module parameters for all possible priority selections.

[0041] Additionally, the method further includes displaying the determined auxiliary module parameters on the machine tool.

[0042] In some embodiments, the priority value is determined automatically, for example, if the auxiliary module automatically detects that the current machining step is a finishing operation, the priority value is automatically set to surface finishing.

[0043] In one variant, the priority value is determined automatically based on information delivered by the auxiliary module.

[0044] In another variation, the priority value is determined automatically based on information delivered by the sensing devices.

[0045] In a further variant, the priority value is determined automatically based on information delivered by the primary control unit.

[0046] In one variation, the priority value is determined automatically based on the job attributes and / or machining steps.

[0047] In particular, the priority values ​​are determined automatically based on databases, physical models, calculations and machine learning.

[0048] Automatic identification of priority values ​​can further improve assistance to the operator in determining the optimum parameters to be applied to the machining process, while still utilizing the full capabilities of the machine.

[0049] In some embodiments, job attributes are identified automatically, for example, the weight of a part can be determined automatically by an auxiliary module, and this information is entered into the enhanced operator assistance system.

[0050] In one variation, the job attributes are determined automatically based on information delivered by the auxiliary module.

[0051] In another variation, the job attributes are determined automatically based on information delivered by the sensing device.

[0052] In a further variation, the job attributes are determined automatically based on information delivered by the primary control unit.

[0053] In one variation, the job attributes are determined automatically based on the priority values ​​and / or machining steps.

[0054] In particular, job attributes are determined automatically based on databases, physical models, calculations and machine learning.

[0055] In an advantageous variant, the machining step can be determined automatically: for example, an auxiliary module by monitoring the axis movements and spindle torques can distinguish between rough or finish machining steps.

[0056] In one variant, the machining steps are determined automatically based on information delivered by an auxiliary module.

[0057] In another variation, the machining steps are determined automatically based on information delivered by the sensing device.

[0058] In a further variation, the machining steps are determined automatically based on information delivered by the primary control unit.

[0059] In particular, the machining steps are determined automatically based on databases, physical models, calculations and machine learning.

[0060] In some embodiments, the priority values ​​and / or job attributes and / or machining steps are manually defined by an operator and automatically verified based on information provided by the primary control unit and / or the auxiliary control unit and / or the sensing unit.

[0061] In some embodiments, the priority values ​​and / or job attributes and / or machining steps are manually defined by an operator and automatically adjusted based on information provided by the primary control unit and / or the auxiliary control unit and / or the sensing unit.

[0062] An essential element for determining machine, cycle, and auxiliary control parameters is an advanced operator assistance system that enables selection of optimal machine settings that meet machine specifications, including target values ​​and job attributes.

[0063] The present invention relates to an augmented operator assistance unit that generates parameters related to operations for machining a workpiece with a machine tool to meet at least one required machining specification. The augmented operator assistance unit includes an input interface configured to receive priority values ​​for at least two interdependent target values ​​representing machining performance, including accuracy, surface finish, and machining time. The augmented operator assistance unit is further configured to receive at least one of job attributes, including complexity, mass inertia, and workpiece weight. In particular, the target values ​​include production cost, machine protection, and energy savings. The augmented operator assistance unit also includes a processing unit configured to automatically determine cycle parameters, machine parameters, and auxiliary control parameters based on the selected priority values ​​and the identified job attributes. The machine parameters and cycle parameters are applied to a primary control unit configured to control the machining, and the auxiliary control parameters are applied to an auxiliary control unit configured to control operations to assist the machining.

[0064] The primary control unit controls the machine tool in such a way that, thanks to the extended operator assistance unit, the optimum machining parameters can be determined by an operator without special programming skills or specific knowledge. All technological variables related to a given machine tool, workpiece, target values, and job attributes such as machining steps are taken into account.

[0065] In some embodiments, the enhanced operator assistance unit comprises an auto-tuning module configured to automatically determine at least one job attribute.

[0066] Furthermore, the auto-tuning module is configured to automatically determine the machining steps.

[0067] In an advantageous variant, the automatic adjustment module is configured to determine the priority value automatically.

[0068] The present invention also relates to a system for machining a workpiece, comprising a primary control unit, a plurality of auxiliary modules, an extended operator assistance system, and an automatic adjustment unit.

[0069] The machine tool includes a spindle for mounting a machining tool to interact with a workpiece for machining.

[0070] The plurality of sensing units are configured to sense one or more of a temperature sensor, a vibration sensor, and a force sensor for the parameter to provide the sensing data.

[0071] The auxiliary control unit is configured to receive the sensory data for controlling the auxiliary module.

[0072] Additionally, the auxiliary control unit can provide the information necessary to automatically determine priority values, job attributes, and machining steps.

[0073] A more detailed description of the principles briefly described above is provided below by reference to specific embodiments thereof illustrated in the drawings. These drawings illustrate exemplary embodiments of the present disclosure and therefore should not be considered limiting of its scope. The principles of the present disclosure will be explained and explained in detail using the accompanying drawings. [Brief explanation of the drawings]

[0074] [Figure 1] FIG. 1 is a schematic diagram showing the connection of an enhanced operator assistance system, an automatic adjustment unit, and an auxiliary module. [Figure 2] FIG. 1 is a schematic diagram showing the connection of an extended operator assistance system, an automatic adjustment unit, and a detection unit.

[0075] MODE FOR CARRYING OUT THE INVENTION Figure 1 is a schematic diagram showing the connection of the extended operator assistance system, the automatic adjustment unit, and the auxiliary module. The input data of the extended operator assistance system 1 are priority values, job attributes, and machining steps. The output data of the extended operator assistance system includes machine parameters, cycle parameters, and auxiliary parameters.

[0076] Priority values, job attributes and machining steps can be set manually by an operator or determined by an automatic adjustment unit 3. Machine and cycle parameters are applied to the primary control unit 2 of the machine tool, while auxiliary parameters are essential data required by the auxiliary modules. Two auxiliary modules are shown in Figure 1; however, besides the thermal error compensation module 5 and the table load compensation module 6, other auxiliary modules can also be applied.

[0077] A sensing unit including multiple sensors is also connected to the primary control unit and the auxiliary module to deliver different sensor data. The auto-tuning unit can automatically determine priority values, job attributes, and machining steps based on the data provided by the auxiliary module.

[0078] FIG. 2 shows an embodiment in which the sensing unit can also directly communicate sensor data to the automatic adjustment unit to determine input data for the augmented operator assistance system. [Explanation of symbols]

[0079] 1. Extended Operator Support System 2 Primary Control Unit 3 Automatic Adjustment Unit 4 Detection unit 5 Thermal Error Compensation Module 6 Table Load Compensation Module

Claims

1. 1. A method for generating parameters to be applied to machining operations performed by a machine tool, comprising: a. providing priority values ​​of at least two interdependent target values ​​representing machining performance, including accuracy, surface finish, and machining time, as input data to an enhanced operator assistance system (1), wherein at least one priority value is automatically determined by an automatic adjustment unit (3); b. providing at least one of job attributes including complexity and workpiece weight as input data to said enhanced operator assistance system; c) automatically determining cycle parameters, machine parameters, and auxiliary module parameters as output data of the augmented operator assistance system based on the priority values ​​and the job attributes by the augmented operator assistance system, wherein the machine parameters and cycle parameters are applied to a primary control unit (2) configured to control movements of different axes to perform the machining, and the auxiliary module parameters are applied to a plurality of auxiliary modules configured to perform the operations to assist the machining. A method for generating parameters to be applied to machining operations performed by a machine tool.

2. The method of claim 1 , wherein the method includes providing machining step information as the input data to the enhanced operator assistance system, and in particular, the machining step information includes roughing, semi-finishing, and finishing.

3. 3. The method according to claim 1, wherein the priority value is automatically determined based on information provided by the auxiliary module, and in particular the automatically determined priority value is automatically transmitted from the automatic adjustment unit to the extended operator assistance system.

4. 4. The method according to claim 1, wherein at least one job attribute is automatically determined by the automatic adjustment unit, and in particular the automatically determined job attribute is automatically transmitted from the automatic adjustment unit to the extended operator assistance system.

5. The method of claim 4 , wherein the weight of the workpiece is determined by the auxiliary module based on information provided by a sensing unit attached to the machine tool.

6. 5. The method according to claim 2, wherein the machining step information is automatically determined by the auto-adjustment module, in particular the automatically determined machining step information is automatically transmitted from the auto-adjustment unit to the extended operator assistance system.

7. 7. The method according to claim 1, wherein the step of automatically determining the auxiliary control parameters comprises mapping the provided priority values ​​to the auxiliary module parameters by using a database or a structured file system, in particular the database comprising predefined tables.

8. The method of claim 1 , further comprising the step of displaying the determined auxiliary module parameters on the machine tool.

9. 1. A system for generating parameters to be applied to machining operations performed by a machine tool, comprising: a. a primary control unit (2) configured to control said machining; b. a plurality of auxiliary modules configured to perform said operations to assist said machining; c. an augmented operator assistance system (1) configured to receive at least two interdependent target values ​​and at least one priority value of job attributes, and to automatically determine cycle parameters, machine parameters, and auxiliary module parameters based on the received priority value and the job attributes, wherein the target values ​​represent machining performance including accuracy, surface finish, and machining time, and the job attributes include complexity and workpiece weight, and the machine parameters and cycle parameters are applied to the primary control unit, and the auxiliary module parameters are applied to the auxiliary module; d. an automatic adjustment unit (3) configured to automatically determine at least one priority value; A system for generating parameters to be applied to machining operations performed by a machine tool.

10. The system of claim 9 , wherein the auto-tuning module is configured to automatically determine at least one job attribute.

11. The system according to claim 9 or 10, wherein the auto-adjustment module is configured to automatically determine the machining steps.

12. The system of claim 9 , wherein the system includes a plurality of sensing units for providing the sensor data to the auxiliary module.

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