METHODS AND SYSTEMS FOR ADAPTING A FEED RATE OF A FEED CONTROL ON NUMERICALLY CONTROLLED MACHINE TOOLS

Abstract

A computer-implemented method provides setpoint values for a feed rate for adaptive feed control on numerically controlled machine tools. Upon machining a workpiece with a tool, receiving a real-time data with a current state of at least one controlled axis, determining actual values of at least one cutting force of the tool based on the real-time data, receiving a look-ahead data associated with a predicted state of the at least one controlled axis, simulating the machining of the workpiece based on the real-time data and the look-ahead data, generating simulated values of the at least one cutting force of the tool, determining at least one setpoint value for the feed rate of the at least one controlled axis based on the simulated values and the actual values of the at least one cutting force of the tool, and providing the at least one setpoint value.

Claims

1-17. (canceled)

18. A computer-implemented method for providing setpoint values for a feed rate for adaptive feed control on numerically controlled machine tools, the method comprising machining a workpiece with a tool, and during the machining: receiving a real-time data associated with a current state of at least one controlled axis, wherein the real-time data comprises measured values of a torque of a spindle; determining actual values of at least one cutting force of the tool from the torque of the spindle; receiving a look-ahead data associated with a predicted state of the at least one controlled axis; simulating the machining of the workpiece based on the real-time data and on the look-ahead data, wherein simulated values of the at least one cutting force of the tool are generated, the simulated values comprising values of the at least one cutting force of the tool predicted in time increments, which are sufficient to adjust the feed rate before a force spike occurs; determining at least one setpoint value for the feed rate of the at least one controlled axis based on the simulated values and on the actual values of the at least one cutting force of the tool; and providing the at least one setpoint value for the feed rate of the at least one controlled axis.

19. The method of claim 18, wherein the real-time data comprises data associated with measured values of the at least one cutting force of the tool and/or speed of the tool and/or position of the tool.

20. The method of claim 18, wherein the look-ahead data comprises data associated with predicted values of speed and/or position of the tool.

21. The method of claim 18, wherein the look-ahead data is generated for a pre-defined time interval, wherein the pre-defined time interval is shorter than a brakeage time of the at least one controlled axis.

22. The method of claim 21, wherein the length of the pre-defined time interval, the pre-defined time interval being a look-ahead time interval, is from about 10 ms to about 1000 ms, particularly 100 ms.

23. The method of claim 18, wherein the simulating the machining of the workpiece comprises, particularly consists of simulating a material removal and calculating the at least one cutting force.

24. The method of claim 18, wherein the simulating the at least one cutting force comprises utilizing at least one of geometry tolerances, material parameters, and tool parameters.

25. The method of claim 18, wherein the determining at least one setpoint value for the feed rate based on the at least one simulated cutting force comprises comparing the simulated values of the at least one cutting force with the actual values of the at least one cutting force, and choosing the at least one setpoint value for the feed rate so that the actual values match the simulated values.

26. The method of claim 18, wherein the time increments are shorter than a brakeage time of the at least one controlled axis.

27. The method of claim 18, wherein the look-ahead data comprises data associated with predicted values of speed and/or position of the tool.

28. A method for adaptive feed control on numerically controlled machine tools, the method comprising machining a workpiece with a tool according to a specification of a part program, and during the machining: acquiring a real-time data associated with a current state of at least one controlled axis; based on the specification of the part program, generating a look-ahead data associated with a predicted state of the at least one controlled axis; providing at least one setpoint value for a feed rate of the at least one controlled axis according to a method of claim 18; and utilizing the at least one setpoint value of the feed rate to control the feed rate of the at least one controlled axis.

29. The method of claim 28, wherein the acquiring is performed periodically, particularly with a period of about 125 ?s to about 5 ms, more particularly with a 2 ms period.

30. A machine-executable component comprising instructions which, when the machine-executable component is executed by a computing system, cause the computing system to carry out a method set forth in claim 18.

31. A system comprising a memory, wherein the memory stores machine-executable components, and a processor, wherein the processor is operatively coupled to the memory and is configured to execute the machine-executable components, wherein the machine-executable components comprise a machine-executable component set forth in claim 30.

32. The system of claim 31, further comprising a numerical control component configured to control at least one axis of a machine tool that comprises a tool and, during machining a workpiece with the tool according to a specification of a part program acquire a real-time data associated with a current state of the at least one controlled axis, based on the specification of the part program, generate a look-ahead data associated with a predicted state of the at least one controlled axis, transfer the real-time data and the look-ahead data to the machine-executable component, receive, from the machine-executable component, at least one setpoint value of the feed rate, and utilize the at least one setpoint value of the feed rate to control the feed rate of the at least one controlled axis.

Description

[0049] The above and other objects and advantages of the invention will be apparent upon consideration of the following detailed description of certain aspects indicating only a few possible ways which can be practiced. The description is taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:

[0050] FIG. 1 schematically illustrates a section of a numerically controlled machine tool,

[0051] FIG. 2 schematically illustrates a system for adaptive feed control of a machine tool,

[0052] FIG. 3 shows a flow diagram of a computer-implemented method for providing setpoint values for a feed rate for adaptive feed control

[0053] FIG. 4 shows a flow diagram of a method for adaptive feed control on numerically controlled machine tools

[0054] FIG. 1 schematically illustrates a section of a numerically controlled machine tool. A workpiece 1 is fastened on a table 4. The workpiece 1 is processed by a tool 2 (here a cutter), which is fixed to a spindle 3 and is rotated by the spindle 3.

[0055] The tool 2 is movable relative to the workpiece 1 in three directions X, Y, Z. Other machine tools may allow further or other directions of movement between tool 2 and workpiece 1, for example by additional pivot axes.

[0056] The machining process is controlled by a numerical control (NC) system 5 that is associated with the machine tool. The NC system 5 controls the axes X, Y, Z of the machine tool. It sends control signals to and receives feedback data from the machine tool (arrows in FIG. 1 go in two directions). The NC system 5 can be designed as a CNC unit.

[0057] FIG. 1 illustrates a sensor device 6 associated with the machine tool. The sensor device 6 can comprise a plurality of different sensors to observe/monitor the machining process and to acquire (e.g. by measuring) different measurement data that can be used to estimate condition of the tool 2 and/or the workpiece 1. The measurement data can comprise acoustic and/or visual measurement and may be associated with vibrations of the tool 2, movements of the tool 2 and/or of the workpiece 1 etc. Therefore, the sensors can be acoustic, vibration, visual sensors etc. The visual sensor can be a camera, e.g. a 3D camera, or based on a laser technology. The sensor device 6 sends the acquired data to the NC system 5.

[0058] The NC system 5 comprises a part program or NC-program 50 and a numerical control (NC) component 51. The basic function of the NC component 51 is to read out the part program and, in a drive control (not shown), to drive the axes X, Y, Z and the spindle 3 in accordance with the specifications of the part program 50.

[0059] The NC component 51 interprets the part program and generates a look-ahead data associated with a predicted state or predicted states of the one or more controlled axes X, Y, Z. The look-ahead data can, for example, comprise a velocity profile for rotating the spindle 3. This allows a smooth and precise motion within the limitations of the drives/controlled axes X, Y, Z.

[0060] In other words, during the machining the movement of the tool 2 is defined according to the specification of the part program 50.

[0061] The NC component 51 can be designed as a software component.

[0062] It will be appreciated that the part program 50 can be a part of the NC component 51.

[0063] Furthermore, FIG. 1 illustrates an edge device 7 associated with the NC system 5. The edge device 7 is configured to exchange data with the NC system 5 and, in particular, with the NC component 51.

[0064] FIG. 2 illustrates a system 100 for adaptive feed control of a machine tool, e.g. of the machine tool of FIG. 1. In other words, FIG. 2 shows aspects regarding the control of the machine tool of FIG. 1 in more details.

[0065] The system 100 comprises the NC system 50 that drives one or more of the axes X, Y, Z and/or the spindle 3. Furthermore, the system 100 comprises the edge device 7. The edge device 7 can be designed as an industrial computing device and usually comprises a memory device and a processor device, wherein the memory device stores machine-executable components, and the processor device is operatively coupled to the memory device and is configured to execute the machine-executable components.

[0066] The edge device 7 comprises a machine-executable situation-awareness-module 70 for providing setpoint values for a feed rate for adaptive feed control on the machine tool.

[0067] In an embodiment the situation-awareness-module 70 can be a part of or integrated into the NC system 5.

[0068] During the machining the workpiece 1 with the tool 2 the situation-awareness-module 70 receives (see e.g. Step M10 in FIG. 3 or 4), for example with a first interface 71, a real-time data 101 associated with a current state of the controlled axes X, Y, Z.

[0069] The real-time data 101 is acquired, e. g. through measuring by the sensor device 6, by the numerical control component 51 (see e.g. Step S10 in FIG. 4). The NC component 51 then sends the real-time data 101 to the situation-awareness-module 70.

[0070] The real-time data 101 can be received continuously or periodically by the situation-awareness-module 70.

[0071] The real-time data 101 can be acquired or measured continuously or periodically by the sensor device 6.

[0072] In an embodiment the acquiring or measuring is performed periodically, particularly with a period of about 125 mus to about 5 ms, more particularly with a 2 ms period.

[0073] The real-time data 101 can comprise data associated with measured values of cutting forces of the tool 2 and/or torque of the spindle 3 and/or speed of the tool 2 and/or position of the tool 2. The position of the tool can be a six-dimensional vector containing information about the position and the orientation of the tool 2.

[0074] Based on the real-time data, the situation-awareness-module 70 determines (see e.g. Step M20 in FIG. 3 or 4) actual values of cutting forces of the tool 2.

[0075] It will be appreciated by the skilled person that the calculation of the actual values of the cutting forces can be performed e.g. either by the NC component 51 or by the situation-awareness-module 70, so that determining actual values of cutting forces of the tool 2 can mean reading out, if the cutting forces are calculated before reaching the situation-awareness-module 70. The actual values of cutting forces can be, for example, calculated by the NC component 51 based on the torque of the spindle.

[0076] Furthermore, the situation-awareness-module 70 receives, for example with the first interface 71 a look-ahead data 102 associated with a predicted state of the controlled axes X, Y, Z.

[0077] It will be appreciated that the situation-awareness-module 70 can comprise different interfaces for receiving the real-time data 101 and the look-ahead data 102.

[0078] The situation-awareness-module 70 receives (see e.g. Step M30 in FIG. 3 or 4) the look-ahead data 102 continuously or periodically.

[0079] The look-ahead data 102 is generated (determined or calculated) by the NC component 51 (see e.g. Step S20 in FIG. 4) based on the specification of the part program 50.

[0080] The look-ahead data 102 can be generated for a pre-defined time interval, wherein, in particular, the pre-defined time interval is shorter than a brakeage time of the controlled axis X, Y, Z.

[0081] The length of the pre-defined time interval (look-ahead time interval) can vary from about 10 ms to about 1000 ms. In an embodiment the look-ahead interval is about 100 ms.

[0082] Based on the real-time data 101 and on the look-ahead data 102 the situation-awareness-module 70 simulates (see e.g. Step M40 in FIG. 3 or 4) the machining of the workpiece 1 and generates simulated values of the cutting forces of the tool 2.

[0083] The simulating the machining of the workpiece 1 can for example comprise simulating a material removal, followed by calculating the cutting forces.

[0084] If the geometry of the workpiece and the path of the tool 2 are not modified during the execution (i.e. not interrupted by the user, no restart after partial completion, . . . ) the step of material removal calculation can be performed offline. However, it can be still beneficial if the cutting force simulation is done entirely online, since the material and tool parameters can be adapted to reality.

[0085] The simulation of the cutting forces can furthermore utilize geometry tolerances, material parameters, tool parameters, or a combination thereof. Each of them has nominal values and some variation (raw workpiece, material batch, tool wear, etc.).

[0086] The simulated values of the cutting forces of the tool 2 can comprise or can be predicted values of the cutting force of the tool 2. The simulation can be performed ahead of real time (look-ahead simulation of the cutting forces).

[0087] In an embodiment the values of the cutting forces of the tool 2 are predicted in time increments which are sufficient to adjust the feed rate before a force spike occurs. In particular the time increments can be shorter than a brakeage time of the controlled axes X, Y, Z, more particularly about 10 times shorter than the above-mentioned look-ahead time intervals.

[0088] The situation-awareness-module 70 can run the simulation continuously or periodically.

[0089] Based on the simulated values and on the actual values of the cutting forces of the tool 2 the situation-awareness-module 70 determines (calculates) setpoint values for the feed rate of the controlled axes X, Y, Z (see e.g. Step M50 in FIG. 3 or 4).

[0090] The determining of the setpoint value for the feed rate based on the at least one simulated cutting force can comprise comparing, e. g. continuously comparing, the simulated values of the cutting forces with the actual values of the cutting forces and choosing the setpoint values for the feed rate so that the actual values match the simulated values.

[0091] Then the situation-awareness-module 70 provides the setpoint values (see e.g. Step M60 in FIG. 3 or 4). FIG. 2 shows an embodiment where the setpoint values are provided with a second interface 72 to the NC component 51 (see e.g. Step S30 in FIG. 4).

[0092] The actions to provide the setpoint values described above are performed during the machining process, i.e. online.

[0093] Subsequently the NC component 51 utilizes (see e.g. Step S40 in FIG. 4) the provided setpoint values of the feed rate to control the feed rate of the controlled axes X, Y, Z.

[0094] In the same manner the situation-awareness-module 70 can (additionally) provide setpoint values of the speed for the controlled axes X, Y, Z, so that the NC component 51 can adapt the speed accordingly.

[0095] FIG. 3 illustrates a flow diagram of a computer-implemented method Ml for providing setpoint values for a feed rate for adaptive feed control on numerically controlled machine tools. The method Ml can be implemented on the system 100 of FIG. 2. The method is carried out during machining a workpiece 1 with a tool 2 and comprises the steps of: [0096] M10 receiving a real-time data 101 associated with a current state of at least one controlled axis X, Y, Z, [0097] M20 determining actual values of at least one cutting force of the tool 2 based on the real-time data, [0098] M30 receiving a look-ahead data 102 associated with a predicted state of the at least one controlled axis X, Y, Z, [0099] M40 simulating the machining of the workpiece 1 based on the real-time data 101 and on the look-ahead data 102, wherein simulated values of the at least one cutting force of the tool 2 are generated, [0100] M50 determining at least one setpoint value 103 for the feed rate of the at least one controlled axis X, Y, Z based on the simulated values and on the actual values of the at least one cutting force of the tool 2, and [0101] M60 providing the at least one setpoint value 103 for the feed rate of the at least one controlled axis X, Y, Z.

[0102] FIG. 4 illustrates a flow diagram of a computer-implemented method S1 for adaptive feed control on numerically controlled machine tools. The method S1 can be implemented on the system 100 of FIG. 2 in a scenario depicted in FIG. 1. The method is carried out during machining a workpiece 1 with a tool 2 according to a specification of a part program 50 and comprises the steps of: [0103] S10 acquiring a real-time data 101 associated with a current state of at least one controlled axis X, Y, Z, [0104] S20 based on the specification of the part program 50, generating a look-ahead data 102 associated with a predicted state of the at least one controlled axis X, Y, Z, [0105] S30 providing at least one setpoint value 103 for a feed rate of the at least one controlled axis X, Y, Z according to the method for providing setpoint values for a feed rate for adaptive feed control on numerically controlled machine tools, e.g. to the method Ml of FIG. 3, [0106] S40 utilizing the at least one setpoint value 103 of the feed rate to control the feed rate of the at least one controlled axis X, Y, Z.

[0107] It will be appreciated that Step 30 comprises at least the steps of the method Ml of FIG. 3 and can comprise corresponding method steps according to one or more embodiments of the system described herein.

[0108] In summary, the adaptation of the simulation parameters of the material removal and cutting force model can yield a higher accuracy of the prediction compared to offline simulations, leading to a higher feed rate (lower production time) without the risk of overload.

[0109] The above-described embodiments of the present disclosure are presented for purposes of illustration and not of limitation. In particular, the embodiments described with regard to figures are only few examples of the embodiments described in the introductory part. Technical features that are described with regard to systems can be applied to augment methods disclosed herein and vice versa.