Vacuum hold-down apparatus

1. A vacuum hold-down system for use with workpieces of various shapes and/or sizes, the system comprising:

a vacuum hold-down table defining a mask support plane; and

an apertured vacuum table mask which is selectably positionable on said mask support plane,

said vacuum hold-down table and said vacuum table mask being configured to define a plurality of selectable different contiguous arrays of vacuum apertures, by suitable relative positioning of said vacuum table mask and said vacuum hold-down table in said mask support plane.

2. The vacuum hold-down system according to claim 1 and wherein:

said vacuum hold-down table has an array of vacuum orifices arranged on a support surface thereof; and

said vacuum table mask has formed thereon at least two arrays of apertures, mutually offset from each other, each of said at least two arrays of apertures being registrable with at least some vacuum orifices of said array of vacuum orifices, each aperture of each of said at least two arrays of apertures being configured to underlie at least one of said workpieces.

3. The vacuum hold-down system according to claim 1 and wherein:

said vacuum table mask has an array of apertures arranged on a support surface thereof, said mask being configured to underlie at least one of said workpieces; and

said vacuum hold-down table has formed thereon at least two arrays of vacuum orifices, mutually offset from each other, at least some of said apertures of said mask being registrable with orifices of each of said at least two arrays of orifices.

4. The vacuum hold-down system according to claim 2 wherein the cross-sectional size of each aperture is at least slightly larger than the cross-sectional size of each vacuum orifice.

5. The vacuum hold-down system according to claim 3 wherein the cross-sectional size of each aperture is at least slightly larger than the cross-sectional size of each vacuum orifice.

6. The vacuum hold-down system according to claim 2 wherein said vacuum table mask is positionable at at least two selectable locations relative to said vacuum hold-down table.

7. The vacuum hold-down system according to claim 3 wherein said vacuum table mask is positionable at at least two selectable locations relative to said vacuum hold-down table.

8. The vacuum hold-down system according to claim 2 and wherein said vacuum table mask includes four arrays of apertures.

9. The vacuum hold-down system according to claim 3 and wherein said vacuum table mask includes four arrays of apertures.

10. The vacuum hold-down system according to claim 8 and wherein said vacuum table mask is positionable at four selectable locations relative to said vacuum hold-down table.

11. The vacuum hold-down system according to claim 9 and wherein said vacuum table mask is positionable at four selectable locations relative to said vacuum hold-down table.

12. The vacuum hold-down system according to claim 10 and wherein said four selectable locations are defined by corners of said vacuum hold-down table.

13. The vacuum hold-down system according to claim 11 and wherein said four selectable locations are defined by corners of said vacuum hold-down table.

14. The vacuum hold-down system according to claim 2 and wherein said vacuum table mask is located over the vacuum hold-down table.

15. The vacuum hold-down system according to claim 3 and wherein said vacuum table mask is located over the vacuum hold-down table.

16. The vacuum hold-down system according to claim 2 and wherein said vacuum table mask is located inside a plenum of the vacuum hold-down table.

17. The vacuum hold-down system according to claim 3 and wherein said vacuum table mask is located inside a plenum of the vacuum hold-down table.

18. The vacuum hold-down system according to claim 2 and wherein areas of said at least two arrays are at least partially overlapping.

19. The vacuum hold-down system according to claim 3 and wherein areas of said at least two arrays are at least partially overlapping.

20. The vacuum hold-down system according to claim 1 and wherein:

said vacuum hold-down table has an array of support surfaces arranged thereon; and

said vacuum table mask has formed thereon an array of apertures.

21. The vacuum hold-down system according to claim 1 and wherein:

said vacuum table mask has an array of apertures, said mask being configured to underlie at least one of said workpieces; and

said vacuum hold-down table has formed thereon at least two arrays of support surfaces, said support surfaces of different arrays of said at least two arrays having a different cross sectional configuration, said support surfaces of each array of said at least two arrays having the same cross sectional configuration, said apertures of said mask being configured so as not to overlie said support surfaces of at least one of said at least two arrays of support surfaces.

22. The vacuum hold-down system according to claim 1 wherein said vacuum table mask is positionable at at least two selectable locations relative to said vacuum hold-down table.

23. The vacuum hold-down system according to claim 1 and wherein said vacuum table mask includes four arrays of apertures.

24. The vacuum hold-down system according to claim 23 and wherein said vacuum table mask is positionable at four selectable locations relative to said vacuum hold-down table.

25. The vacuum hold-down system according to claim 24 and wherein said four selectable locations are defined by corners of said vacuum hold-down table.

26. The vacuum hold-down system according to claim 20 and wherein said vacuum table mask is located over said support surfaces.

27. A vacuum table mask for use with a vacuum hold-down table having an array of vacuum orifices arranged on a support surface thereof and workpieces of various shapes and/or sizes, said mask comprising:

a substrate having formed thereon at least two arrays of apertures, mutually offset from each other, each of said at least two arrays of apertures being registrable with at least some vacuum orifices of said array of vacuum orifices, and

wherein areas of said at least two arrays are at least partially overlapping.

28. The vacuum table mask according to claim 27 and wherein the cross-sectional size of each aperture of said at least two arrays of apertures is at least slightly larger than the cross-sectional size of each vacuum orifice of said array of vacuum orifices.

29. The vacuum table mask according to claim 27 and wherein said vacuum table mask includes four arrays of apertures.

30. A method for providing vacuum hold-down of workpieces of various shapes and/or sizes onto a vacuum hold-down table having an array of vacuum orifices arranged on a support surface thereof, the method comprising:

placing onto said support surface of said vacuum hold-down table, a vacuum table mask having formed thereon at least two arrays of apertures, mutually offset from each other, each of said at least two arrays of apertures being registrable with at least some vacuum orifices of said array of vacuum orifices, each of said at least two arrays of apertures being configured to underlie one of said workpieces;

positioning said mask on said support surface such that one of said at least two arrays of apertures is in registration with at least some vacuum orifices of said array of vacuum orifices;

placing a workpiece of a first size/shape of said workpieces of various shapes and/or sizes onto said vacuum hold-down table, overlying at least part of said mask and overlying said one of said at least two arrays of apertures which is in registration with at least some vacuum orifices of said array of vacuum orifices;

removing said workpiece of a first size/shape from said vacuum hold-down table;

repositioning said mask on said support surface such that another one of said at least two arrays of apertures is in registration with at least some vacuum orifices of said array of vacuum orifices; and

placing one of said workpieces of a second size/shape onto said vacuum hold-down table, overlying at least part of said mask and overlying said another one of said at least two arrays of apertures which is in registration with at least some vacuum orifices of said array of vacuum orifices;

wherein areas of said at least two arrays are at least partially overlapping.