Automatic allocation of machining operations to a plurality of machining stations

• US 6,668,208 B2
• Filed: 12/11/2001
• Issued: 12/23/2003
• Est. Priority Date: 12/14/2000
• Status: Expired due to Fees

• Current Assignee: Witzig & Frank GmbH
• Original Assignee: Witzig & Frank GmbH
• Inventors: Bauer, Walter, Baumbusch, Frank
• Primary Examiner(s): PALADINI, ALBERT WILLIAM
• Application Number:
  US10/015,159
• Publication Number:
  US 20020107606A1
• Time in Patent Office: 742 Days
• Field of Search: 700/100, 700/99, 700/113, 700/114, 700/169, 700/112, 700/159, 295/63, 414/222.13, 483/15
• US Class Current: 700/169
• CPC Class Codes: G05B 19/41865 characterised by job scheduling, process planning, material flow
• CPC Class Codes: G05B 2219/32118 Loading, allocates operations and tools to selected part type
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A technique for controlling a machining system having a plurality of machining stations for machining workpieces with a plurality of machining operations. Each of the plurality of machining operations is allocated automatically to a specific one of the machining stations to attain uniform utilization of the individual machining stations, to the extent possible. This facilitates the initial setup of the machining system as well as correcting the setup if machining errors or deviations occur.

Claims

1. A machining system for machining a workpiece, comprising:

a plurality of machining stations with each one having at least one work spindle;

means for providing machining information related to a plurality of machining operations specific to a particular workpiece;

distribution means for automatically allocating the plurality of machining operations to the plurality of machining stations; and

processing means for controlling said machining stations in accordance with the machining information related to the allocated machining operations.

2. The machining system of claim 1, wherein the means for providing the machining information related to the plurality of machining operations comprises a memory in which the machining information is stored.

3. The machining system of claim 1, wherein the distribution means comprises:

means for determining a preliminary machining cycle time applied to each of the machining stations,

means for automatically selecting from among the plurality of machining operations and filling-in said preliminary machining cycle time for the plurality of machining stations with the selected machining operations until all of said machining operations have been selected, to generate a preliminary allocation of machining operations,

means for determining resultant machining cycle times for the respective machining stations based on said machining information corresponding to the machining operations selected and allocated in said preliminary allocation of machining operations, and

means for re-allocating the machining operations if the resultant machining cycle times based on the preliminary allocation vary from each other by more than a predetermined difference.

4. The machining system of claim 3, wherein the selecting means selects machining operations in order of their respective machining times, with the machining operation having the longest machining time being selected first.

5. The machining system of claim 4, wherein the means for providing the plurality of machining operations includes means for specifying a required sequencing for designated machining operations, and wherein said selecting means selects machining operations in accordance with the required sequencing.

6. The machining system of claim 1, wherein said processing means includes means for converting the machining information related to the allocated machining operations into machining control instructions.

7. The machining system of claim 6, further comprising measuring means for checking workpiece dimensions machined in accordance with the allocated machining operations to produce a correction output, and wherein said processing means comprises means for correcting the machining control instructions in accordance with the correction output.

8. The machining system of claim 6, wherein the processing means comprises means for determining a calculated machining cycle time for each of the machining stations based on the machining control instructions, and means for re-allocating the machining operations if the calculated machining cycle times based on the machining control instructions vary from each other by more than a predetermined difference.

9. The machining system of claim 1, wherein the distribution means comprises means for determining a cycle time for each of the machining stations by totaling machining times for all of the machining stations allocated thereto, and means for re-allocating the machining operations if the machining cycle times obtained from the machining times based on the preliminary allocation vary from each other by more than a predetermined difference.

10. A method for machining a workpiece with a plurality of machining stations, with each one having at least one work spindle, comprising:

providing machining information related to a plurality of machining operations specific to a particular workpiece;

automatically allocating the plurality of machining operations to the plurality of machining stations; and

controlling the machining stations in accordance with the machining information related to the allocated machining operations.

11. The method of claim 10, wherein the step of providing the machining information related to the plurality of machining operations comprises retrieving the machining information from a memory.

12. The method of claim 10, wherein the step of automatically allocating the plurality of machining operations comprises:

determining a preliminary machining cycle time applied to each of the machining stations,

automatically selecting from among the plurality of machining operations and filling-in said machining cycle time for the plurality of machining stations with the selected machining information until all of said machining operations have been selected, to generate a preliminary allocation of machining operations,

determining resultant machining cycle times for the respective machining stations based on the preliminary allocation, and

re-allocating the machining operations if the resultant machining cycle times based on the preliminary allocation vary from each other by more than a predetermined difference.

13. The method of claim 12, wherein the selecting step selects machining operations in order of their respective machining times, with the machining operation having the longest machining time being selected first.

14. The method of claim 12, wherein the step of providing the plurality of machining operations includes specifying a required sequencing for designated machining operations, and wherein said selecting step selects machining operations in accordance with the required sequencing.

15. The method of claim 10, wherein said controlling step includes converting the machining information related to the allocated machining operations into machining control instructions.

16. The method of claim 15, further comprising checking workpiece dimensions machined in accordance with the allocated machining operations to produce a correction output, and wherein said controlling step comprises correcting the machining control instructions in accordance with the correction output.

17. The method of claim 15, wherein the controlling step comprises determining a calculated machining cycle time for each of the machining stations based on the machining control instructions, and re-allocating the machining operations if the calculated machining cycle times based on the machining control instructions vary from each other by more than a predetermined difference.

18. The method of claim 10, wherein the allocating step comprises determining a cycle time for each of the machining stations by totaling machining times for all of the machining stations allocated thereto, and re-allocating the machining operations if the machining cycle times obtained from the machining times based on the preliminary allocation vary from each other by more than a predetermined difference.

19. An article of manufacture for use in a computerized machining system, for machining a workpiece with a plurality of machining stations each one having at least one work spindle, and having a computer-readable code means for:

providing machining information related to a plurality of machining operations specific to a particular workpiece;

automatically allocating the plurality of machining operations to the plurality of machining stations; and

controlling the machining stations in accordance with the machining information related to the allocated machining operations.

20. The article of manufacture of claim 19, wherein the function of providing the machining information related to the plurality of machining operations comprises retrieving the machining information from a memory.

21. The article of manufacture of claim 19, wherein the function of automatically allocating the plurality of machining operations comprises:

determining a preliminary machining cycle time applied to each of the machining stations,

automatically selecting from among the plurality of machining operations and filling-in said machining cycle time for the plurality of machining stations with the selected machining information until all of said machining operations have been selected, to generate a preliminary allocation of machining operations,

determining resultant machining cycle times for the respective machining stations based on the preliminary allocation, and

re-allocating the machining operations if the resultant machining cycle times based on the preliminary allocation vary from each other by more than a predetermined difference.

22. The article of manufacture of claim 21, wherein the selecting function selects machining operations in order of their respective machining times, with the machining operation having the longest machining time being selected first.

23. The article of manufacture of claim 21, wherein the function of providing the plurality of machining operations includes specifying a required sequencing for designated machining operations, and wherein said selecting function selects machining operations in accordance with the required sequencing.

24. The article of manufacture of claim 19, wherein said controlling function includes converting the machining information related to the allocated machining operations into machining control instructions.

25. The article of manufacture of claim 24, wherein the computer-readable code means further provides the function of checking workpiece dimensions machined in accordance with the allocated machining operations to produce a correction output, and wherein said controlling function comprises correcting the machining control instructions in accordance with the correction output.

26. The article of manufacture of claim 24, wherein the controlling function comprises determining a calculated machining cycle time for each of the machining stations based on the machining control instructions, and re-allocating the machining operations if the calculated machining cycle times based on the machining control instructions vary from each other by more than a predetermined difference.

27. The article of manufacture of claim 19, wherein the allocating function comprises determining a cycle time for each of the machining stations by totaling machining times for all of the machining stations allocated thereto, and re-allocating the machining operations if the machining cycle times obtained from the machining times based on the preliminary allocation vary from each other by more than a predetermined difference.

28. A machining system (1),

having a plurality of machining stations (S1, S2, S3), which each have at least one work spindle (A1) and serve to perform specified machining operations (B1, . . . , BN) on workpieces,

having a control device, which has an allocation module (27) for automatically allocating the specified machining operations (B1, . . . , BN) to the machining stations (S1, S2, S3) and to the work spindle (A1).

29. The machining system of claim 28, characterized in that the allocation module is connected to a memory device, which contains a list of the machining operations (B1, . . . , BN) to be performed on the workpiece.

30. The machining system of claim 29, characterized in that in the list, the assigned machining times (ti) are noted.

31. The machining system of claim 29, characterized in that in the list, the necessary machining sequences are noted.

32. The machining system of claim 29, characterized in that the allocation module allocates the required machining operations (Bi) of the list to the machining stations (S1, S2, S3) in such a way that chronological differences between the machining operations to be performed in the machining stations (S1, S2, S3) are minimized.

33. The machining system of claim 32, characterized in that the allocation module generates station lists with the machining operations to be performed for each machining station (S1, S2, S3) and each work spindle (A1, A2, A3, A4, A5, A6), and that there is a calculation module, which converts the station lists into the control data files, which contain positioning commands for the machining stations (S1, S2, S3).

34. The machining system of claim 33, characterized in that the allocation module is connected to the calculation module, in order to obtain the cycle times that result from combining the individual machining operations.

35. The machining system of claim 34, characterized in that the allocation module checks the allocation made of the machining operations to machining stations (S1, S2, S3) on the basis of the cycle times obtained from the calculation module and changes it, if the calculated cycle times at the individual machining stations (S1, S2, S3) have differences that exceed a predetermined upper limit.

36. A machining system,

having a plurality of machining stations (S1, S2, S3), which each have at least one work spindle (A1) and serve to perform specified machining operations (B1, . . . , BN) from different machining directions, on multi-sided workpieces,

having a control device, which has a memory device for storing an allocation of the specified machining operations (B1, . . . , BN) to the machining stations (S1, S2, S3) and to the work spindle (A1),

having a coordinate transformation device for converting workpiece-referred desired dimensions into positioning commands for the machining stations (S1, S2, S3) in their own coordinate systems,

wherein the coordinate transformation device is connected to the memory device in order to perform the coordinate transformation on the basis of the allocation, stored in the memory device, of the specified machining operations (B1, . . . , BN) to the machining stations (S1, S2, S3) and to the work spindle (A1).

37. The machining system of claim 36, characterized in that in the machining stations (S1, S2, S3), each comprising at least two machining units (R1, R2), are disposed, which are arranged to machine the workpiece from two different directions.

38. The machining system of claim 37, characterized in that for positioning the workpieces in the machining stations (S1, S2, S3), workpiece receptacles are provided.

39. The machining system of claim 38, characterized in that the workpiece receptacles are each connected to positioning devices, which serve to move the workpiece, in the applicable machining station (S1, S2, S3), into machining positions different from one another and fix them in these positions as needed.

40. The machining system of claim 36, characterized in that in the control device, each of the machining stations (S1, S2, S3) is allocated its own coordinate system.

41. The machining system of claim 36, characterized in that the machining units (S1, S2, S3) are embodied as identical to one another, at least within groups.

42. The machining system of claim 36, characterized in that the workpieces are conveyed in synchronization from one machining station to another by means of a transporting device.

43. The machining system of claim 36, characterized in that the coordinate transformation device is connected to receive an output of a correction device, which is connected to receive an output of a measuring instrument that is arranged to measure actual workpiece dimensions.

44. An article of manufacture for use in a computerized machining system, and having a computer-readable code means, wherein the machining system includes a plurality of machining stations (S1, S2, S3), in which workpieces can be put in different machining positions by means of positioning devices and machined in these positions, and each of the machining stations having machining units (R1, R2), which have work spindles (A1, A2, . . . ), which can be positioned with respect to the workpieces by means of adjusting devices,

wherein the computer-readable code means receives workpiece dimensions of the workpiece to be produced and the machining operations (Bi) required to produce it and automatically distributes the machining operations (Bi), in accordance with their order to the machining stations (S1, S2, S3) and machining units (R1, R2) in such a way that the utilization of the individual machining stations (S1, S2, S3) and machining units (R1, R2) is essentially equal.

45. An article of manufacture for use in a computerized machining system, and having a computer-readable code means, wherein the machining system includes a plurality of machining stations (S1, S2, S3), in which workpieces can be put in different machining positions by means of positioning devices and machined in these positions, and each of the machining stations having machining units (R1, R2), which have work spindles (A1, A2, . . . ), which can be positioned with respect to the workpieces by means of adjusting devices,

wherein the computer-readable code means has an allocation module, which automatically allocates the required machining operations to certain machining stations, workpiece positions and machining units (R1, R2) and work spindles (A1, A2, . . . ) and generates corresponding control instructions in machining station-specific coordinate systems.

46. The article of manufacture of claim 45, characterized in that in a machining system having a measurement station for measuring the workpiece dimensions of a fully machined workpiece, it uses the measurement data in a coordinate system referred to the workpiece to monitor the outcome of machining.

47. The article of manufacture of claim 46, characterized in that the computer-readable code means changes the control instructions via the allocation module, if the measurement data are outside a specified tolerance.