SOFTWARE MODULE, PRECISION MACHINE, METHOD AND COMPONENT

Abstract

A software module calculates a 3D tool path with integrated reference variable generation for interpolating moving single axes of a precision machine. A precision machine has a control or drive servo-side interface, in order to read in advance for machining calculated files with equitemporal reference variables for interpolating single axes of the precision machine and to stream to the position and/or velocity controller of the respective individual axes. A method calculates a 3D tool path and a component is produced with this precision machine or with such a method.

Claims

1. A software module for calculating a 3D tool path with integrated reference variable generation for interpolating moving single axes of a precision machine, wherein as interface output of the software module for controlling the precision machine, position target values are output as a reference variable for each interpolating moving single axis of the precision machine with equitemporal distances in a continuous individual file or a plurality of individual files.

2. The software module according to claim 1, wherein as interface output, in addition to the position target values of the individual axes, velocity, acceleration or jerk values with equitemporal intervals are output as additional reference variables for the single-axis control.

3. The software module according to claim 1, wherein the calculation of the reference variables is carried out analytically in order to follow with a previously defined working contour, such as in particular a cutting contour of the tool, the 3D tool path underlying the calculations exactly or up to a defined residual error.

4. A precision machine with a control or drive servo-side interface, in order to read in advance for machining calculated files with equitemporal reference variables for interpolating single axes of the precision machine and to stream to the position and/or velocity controller of the respective individual axes.

5. A method for calculating a 3D tool path with integrated reference variable generation for interpolating moving single axes of a precision machine, wherein for the control of the precision machine, position target values are output as a reference variable for each interpolating moving single axis of the precision machine with equitemporal distances in a continuous individual file or a plurality of individual files.

6. The method according to claim 5, wherein the calculation of the reference variables for the interpolating individual axes is carried out such that the velocity of a main spindle in the axis group is continuously increased to a defined maximum value to ensure a constant longest possible cutting velocity in the turning process.

7. The method according to claim 5, wherein a starting velocity for all individual axes along a complete 3D path or a subsystem of the individual axes in a partial projection of the 3D path is specified and before driving the individual axes, the other reference variables of the individual axes are fully calculated with temporal reference such as speed, acceleration and/or jerk.

8. The method according to claim 7, wherein after the calculation of the reference variables based on the starting velocity, the reference variables velocity, acceleration and jerk are maximized taking into account predetermined dynamic limit values locally along the entire 3D path.

9. The method according to claim 8, wherein after local maximization of the reference variables velocity, acceleration and jerk, the respective reference variable profiles, in particular acceleration and jerk, are smoothed over individual sub-segments of the path in order to achieve an increase in precision on these sub-segments in particular with respect to dimensional stability or surface roughness.

10. The method according to claim 5, wherein before controlling the individual axes, a complete reference variable data set is calculated and optimized analytically precisely for the entire 3D space curve or subsections of the curve.

11. The method according to claim 10, wherein for the creation of the reference variable data set, iterative, numerical calculations or analytically precise calculations for the interpolation are performed in parallel on several kernels and then assembled in a synchronized manner in order to achieve an acceleration of the production compared to single-kernel calculations.

12. The method according to claim 5, wherein by an analytical calculation, a number of the position target values per single axis greater than 3,000 points/s, preferably greater than 5,000 points/s or even greater than 10,000 points/s, are output in polynomial-based calculation.

13. The method according to claim 5, wherein the motion profiles are stored in files as a buffer before the control of the individual axes, which are streamed with data rates greater than 3,000 points/s, advantageously greater than 5,000 points/s or even greater 10,000 points/s, directly to a servo to drive a single axis with decentralized integrated position control.

14. The method according to claim 5, wherein the motion profiles are stored in files as a buffer before the control of the individual axes, which are streamed with data rates greater than 3,000 points/s, advantageously greater than 5,000 points/s or even greater 10,000 points/s, directly to a position controller which runs centrally on a computer of precision machine.

15. The method according to claim 13, wherein during the streaming of the pre-calculated values, the path velocity of the tool is influenced by a limiting actuator (override).

16. The method according to claim 13, wherein the files are called from a conventional CNC program of the precision machine as a subroutine, started and terminated.

17. A component manufactured by a precision machine according to claim 4.

18. A component manufactured by a method according to claim 5.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other objects and features of the invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention.

[0033] In the drawings,

[0034] FIG. 1 schematically shows a surface which can be described by point clouds or can be approximated as closed surfaces by geometric elements.

[0035] FIG. 2 shows a milling tool guided over a material blank with a respective infeed between the individual grid steps via a meandering grid in order to generate a surface on the component.

[0036] FIG. 3 shows the distance between interpolation points for describing the path.

[0037] FIG. 4 shows a linear interpolation.

[0038] FIG. 5 shows a polynomial interpolation.

[0039] FIG. 6 shows a movement profile using the example of x, y, and z axes.

[0040] FIG. 7 shows determination of spatially and temporally synchronized movements of the individual axes taking into account the real performance of the machine tool.

[0041] FIG. 8 shows the programmed set path for eight blocks.

[0042] FIG. 9 shows a velocity profile for the geometric path of FIG. 8 with a look-ahead function.

[0043] FIG. 10 shows a velocity profile for the geometric path of FIG. 8 without a look-ahead function.

[0044] FIG. 11 shows the reference variables for a simple movement of an axis between two points calculated via the polynomial-based offline approach according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0045] The procedure described is not an optimization step during the CAD/CAM routine, but rather the actual functionality of the CNC. The calculated data are preferably no longer pushed through another CNC kernel, but flow directly to the position controller of the single axis.

[0046] Using the look-ahead in a conventional CNC control, a velocity planning for the guidance of the tool is carried out in such a way a following of the path is realized as quickly as possible, taking into account the specified target speed, without violating the contour (geometry).

[0047] Acceleration and jerk are calculated as a result of the velocity planning. If there are overshoots of predefined limit values during acceleration or jerk, the velocity is reduced at the respective points until the permissible limit values are exceeded.

[0048] As a result, the limit values of velocity, acceleration or jerk are never exceeded across the entire path. However, it may be that the course of the acceleration and the jerk is very uneven or noisy. This leads to dynamic unwanted excitations in the machine, which lead to a deterioration of the surface quality.

[0049] FIGS. 7 and 11 show the reference variables for a simple movement of an axis between two points. FIG. 7 was conventionally calculated via a CNC linear block and FIG. 11 via the polynomial-based offline approach according to the invention. In particular, the differences in acceleration and jerk are noticeable in this case.

[0050] This makes it possible, if necessary (there may be many reasons for a higher frequency excitation, e.g., surface structure, limit movement cases of the axes, chipping of special materials) for velocity, acceleration and jerk to optionally introduce new smoothing functions that not only locally control and reduce a limit value (and thereby lead to high-frequency excitation), but achieve a continuous smoothing and thus a calming of the tool guide over a sub-segment of the path. Such a smoothing function results in influencing or reducing the velocity in the respective area.

[0051] In practice, the method can be described in three steps:

[0052] 1. Calculating all reference variables with temporal reference (velocity, acceleration, jerk) for the individual axes on the basis of a starting velocity, which is not a reference variable.

[0053] 2. Adjusting these calculated reference variables locally along the entire 3D path such that predefined maximum values for velocity, acceleration, jerk are not exceeded.

[0054] 3. Smoothing the adjusted reference variable profiles for velocity, acceleration, and jerk along parts according to a given requirement, such as short machining time (smooth, maximized velocity), or good surface roughness (smoothing the acceleration profile of the axes for smooth behavior). In this case, the smoothing of any desired reference variable profile (e.g., acceleration) always has an influence on all other profiles (e.g., jerk, velocity).

[0055] This makes it possible to increase the machining velocity significantly and to increase the quality of the machining by an increased number of interpolation points per second. This is needed for precision machines and especially for high-precision machine tools to be able to produce, for example, structures for head-up displays significantly faster.

[0056] A novel feature with respect to the prior art is the possibility of making a continuous adjustment of the spindle velocity up to a maximum value with the method without there being any influence on surface quality.

[0057] Although only a few embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.