METHOD FOR MACHINING A SERIES OF WORKPIECES BY MEANS OF AT LEAST ONE MACHINING JET

• US 20140170935A1
• Filed: 12/18/2013
• Published: 06/19/2014
• Est. Priority Date: 12/18/2012
• Status: Active Grant

• Current Assignee: Micro Waterjet AG
• Original Assignee: Micromachining AG
• Inventors: MAURER, Walter
• Granted Patent: US 9,039,485 B2
• Time in Patent Office: Days
• US Class Current: 451/8
• CPC Class Codes: B23K 2101/001 Turbines
• CPC Class Codes: B23K 26/03 Observing, e.g. monitoring, the workpiece
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/0884 in at least in three axial directions, e.g. manipulators, robots
• CPC Class Codes: B23K 26/38 by boring or cutting
• CPC Class Codes: B23K 26/389 of fluid openings, e.g. nozzles, jets laser machining of inkjet nozzles B41J2/1634
• CPC Class Codes: B23K 37/0235 the guide member forming part of a portal
• CPC Class Codes: B24B 49/02 according to the instantaneous size and required size of the workpiece acted upon, the measuring or gauging being continuous or intermittent B24B49/12 takes precedence
• CPC Class Codes: B24C 1/045 for cutting energy dissipating devices therefor B26F3/008
• CPC Class Codes: B24C 3/04 stationary
• CPC Class Codes: B26D 5/00 Arrangements for operating and controlling machines or devices for cutting, cutting-out, stamping-out, punching, perforating, or severing by means other than cutting
• CPC Class Codes: B26D 5/005 Computer numerical control means
• CPC Class Codes: B26F 3/004 by means of a fluid jet methods for use of abrasive blasting for cutting B24C1/045; guns for abrasive fluid jets B24C5/02; perforating by non-mechanical means, e.g. by fluid jet B26F1/26

Abstract

The method for machining a series of workpieces (21) via at least one machining jet includes the following steps:

• • each workpiece (21) is associated with an identifier for uniquely identifying the workpiece,
  • during the machining of a respective workpiece, the temporal characteristic of the machining jet is detected by at least one sensor (30),
  • the detected temporal characteristic is evaluated so as to obtain at least one comparative value, and
  • for detecting incorrect machining, the at least one comparative value is compared with at least one threshold value.

Claims

1. A method for machining a series of workpieces by means of at least one machining jet, wherein in the method

each workpiece is associated with an identifier for uniquely identifying the workpiece,

during the machining of a respective workpiece, a temporal characteristic of said at least one machining jet is detected by means of at least one sensor,

the detected temporal characteristic is evaluated so as to obtain at least one comparative value, and

for detecting incorrect machining, said at least one comparative value is compared with at least one threshold value.

2. The method according to claim 1, wherein the respective workpiece is associated with an error indicator which is determined as a function of a deviation of said at least one comparative value from said at least one threshold value.

3. The method according to claim 2, wherein the error indicator comprises a flag.

4. The method according to claim 2, wherein information can be obtained from the error indicator, which information indicates at which of the machining areas, at which the workpiece has been machined by means of said at least one machining jet, the absolute value of said at least one comparative value is greater than said at least one threshold value.

5. The method according to claim 1, wherein said at least one comparative value is formed as a function of a predetermined expectation value.

6. The method according to claim 5, wherein said at least one comparative value Uv is formed as absolute value of the difference between a measurement signal U of said at least one sensor and the expectation value Ue:

Uv=|U−

Ue|.

7. The method according to claim 1, wherein the existence of an error during machining is determined as a function of the following criterion:

when machining a workpiece, there is at least one time interval which lasts at least for a predetermined time, and during which the absolute value of said at least one comparative value exceeds said at least one threshold.

8. The method according to claim 1, wherein a calibration is carried out in which, with said at least one machining jet turned on, a signal of said at least one sensor is detected as a function of a distance of said at least one machining jet from a point of origin.

9. The method according to claim 8, wherein the calibration is carried out prior to machining the series of workpieces.

10. The method according to claim 1, wherein said at least one sensor is part of a closed loop control for changing a characteristic of said at least one machining jet in dependence on a deviation of said at least one comparative value from said at least one threshold value.

11. The method according to claim 10, wherein the closed loop control comprises at least one of the following components:

a drive for moving said at least one machining jet,

a pump for ejecting said at least one machining jet under pressure out of a machining head,

a dosing device for adding abrasive material to said at least one machining jet.

12. The method according to claim 1, wherein machining a workpiece is interrupted if said at least one comparative value exceeds or falls below said at least one threshold value several times in a row.

13. The method according to claim 1, wherein, during the machining, a workpiece is supported on a workpiece support which comprises said at least one sensor.

14. The method according to claim 1, wherein said at least one sensor is configured to perform at least one of the following operations:

detecting vibrations in at least one of a solid body, a liquid and air,

detecting a pressure which said at least one machining jet exerts onto a workpiece support or a workpiece or onto both,

detecting said at least one machining jet optically.

15. The method according to claim 1, wherein said at least one machining jet is formed from at least one of the following media:

a liquid with or without abrasive particles,

gas,

photons.

16. The method according to claim 1, wherein the obtaining of said at least one comparative value comprises a comparison of the detected temporal characteristic with calibration values, which define a change of a signal of said least one sensor when a distance between said at least one machining jet and said at least one sensor is changed.

17. The method according to claim 1, wherein, for detecting an incorrect setting, said at least one comparative value is obtained by evaluating the acquired temporal characteristic and comparing it with data stored, which data define a relationship between setting parameters and a sensor signal to be expected and which data are used for obtaining said at least one threshold value.

18. The method according to claim 17, wherein the comparison is done in a frequency spectrum.

19. The method according to claim 1, wherein for the respective machined workpiece data are stored, which comprise the identifier and information on the detected temporal characteristic, wherein the data serves for a verification of required production conditions.

20. The method according to claim 1, wherein machining the series of workpieces comprises at least one of structuring a workpiece surface, compacting a workpiece surface, cutting and drilling.

21. A machining device, which is configured to implement the method according to claim 1, wherein

the machining device is configured to generate during the operation at least one machining jet for machining workpieces, the machining device

comprising at least one sensor for detecting a temporal characteristic of said at least one machining jet when machining the workpieces, wherein

the machining device is provided with a program on execution of which the method is implementable.

22. The machining device according to claim 21, further comprising a workpiece support which comprises said at least one sensor and on which a workpiece is supported during machining.

23. The machining device according to claim 21, further comprising a workpiece support which comprises a frame on which a workpiece can be fastened by means of holding means.