EP0240150A2 — Workpiece position control

Claim 1

Independent Claim 335 words

Apparatus for performing an operation on a workpiece, comprising a support (20) rotatable about a predetermined axis (23) a workpiece receiving member (4) mounted on said rotatable support (20) for rotation therewith, first means (46, 50a, 50b) supporting said receiving member for tilting movement in any direction relative to said rotatable support (20), second means (22) supporting said receiving member (4) for transverse movement relative to said rotatable support (20), first and second drive means (62a, 62b; 26x, 26y) for respectively effecting said tilting and transverse movements, third drive means (74) for rotating said rotatable support (20), a surface sensor (10) mounted for movement substantially parallel to and towards and away from said axis (23), fourth drive means (76, 78) for effecting said movement of said sensor, said surface sensor (10) being adapted to traverse and sense the workpiece surface during relative movement between the sensor (10) and the workpiece, and computer means (72) which is responsive to said sensor (10) and includes program means for detecting centring and levelling errors and for actuating said first and second drive means (62a, 62b; 26x, 26y) to perform a centring and levelling correcting operation, characterised in that said first supporting means comprises three support elements (46, 50a, 50b) supporting said receiving member (4) at only three points (A,B,P) at the apices of a triangle (A,P, B) within which the centre (C) of the workpiece receiving member (4) is located, said first drive means (62a, 62b) being operative to adjust at least two of said support elements (50a, 50b) so that adjustment of one of said support elements (50a, 50b) tilts the receiving member (4) about a respective tilt axis (PB or PA) extending substantially between the other two said elements (46 and 50b or 50a), and characterised in that said program means is operative to control said first drive means (62, 62b) dependent upon the angle (PAB) between said tilt axes (PB,PA) and to control said second drive means (26x, 26y) dependent upon any said levelling errors.

Claim 2

Dependent Claim 335 words

Apparatus for performing an operation on a workpiece, comprising a support (20) rotatable about a predetermined axis (23) a workpiece receiving member (4) mounted on said rotatable support (20) for rotation therewith, first means (46, 50a, 50b) supporting said receiving member for tilting movement in any direction relative to said rotatable support (20), second means (22) supporting said receiving member (4) for transverse movement relative to said rotatable support (20), first and second drive means (62a, 62b; 26x, 26y) for respectively effecting said tilting and transverse movements, third drive means (74) for rotating said rotatable support (20), a surface sensor (10) mounted for movement substantially parallel to and towards and away from said axis (23), fourth drive means (76, 78) for effecting said movement of said sensor, said surface sensor (10) being adapted to traverse and sense the workpiece surface during relative movement between the sensor (10) and the workpiece, and computer means (72) which is responsive to said sensor (10) and includes program means for detecting centring and levelling errors and for actuating said first and second drive means (62a, 62b; 26x, 26y) to perform a centring and levelling correcting operation, characterised in that said first supporting means comprises three support elements (46, 50a, 50b) supporting said receiving member (4) at only three points (A,B,P) at the apices of a triangle (A,P, B) within which the centre (C) of the workpiece receiving member (4) is located, said first drive means (62a, 62b) being operative to adjust at least two of said support elements (50a, 50b) so that adjustment of one of said support elements (50a, 50b) tilts the receiving member (4) about a respective tilt axis (PB or PA) extending substantially between the other two said elements (46 and 50b or 50a), and characterised in that said program means is operative to control said first drive means (62, 62b) dependent upon the angle (PAB) between said tilt axes (PB,PA) and to control said second drive means (26x, 26y) dependent upon any said levelling errors.

Claim 3

Dependent Claim 22 words

Apparatus according to claim 1, characterised in that said angIe (PAB) between said tilt axes (PA,PB) is other than a right angle.

Claim 4

Dependent Claim 27 words

Apparatus according to claim 2, characterised in that said points (P,A,B) are located at the apices of an equilateral triangle, said angle (PAB) thereby being 60 degrees.

Claim 5

Dependent Claim 25 words

Apparatus according to claim 3, characterised in that said points (P,A,B) are symmetrically disposed relative to the centre (C) of said workpiece receiving member (4).

Claim 6

Dependent Claim 29 words

Apparatus according to claim 4, characterised in that only two of said three support elements (50a, 50b) are adjustable, the third of said three support elements (46) being fixed.

Claim 7

Dependent Claim 32 words

Apparatus according to claim 5, characterised in that said first drive means comprises first and second motors (62a, 62b) for effecting said tilting about said first and second tilt axes (PB,PA) respectively.

Claim 8

Dependent Claim 30 words

Apparatus according to any preceding claim, characterised in that said second drive means comprises first and second motors (26x, 26y) for effecting said transverse movement in respective orthogonal directions (x,y).

Claim 9

Dependent Claim 37 words

Apparatus according to claim 7, characterised in that said orthogonal directions (x,y) are bisected by a line which is equidistant from said at least two support elements (50a, 50b) and passes through said third support element (46).

Claim 10

Dependent Claim 15 words

Apparatus according to any preceding claim, characterised in that said predetermined axis (23) is vertical.

Claim 11

Dependent Claim 16 words

Apparatus according to claim 9, characterised in that said workpiece receiving member (4) is a turntable.

Claim 12

Dependent Claim 69 words

Apparatus according to any preceding claims, characterised in that said program means is operable for performing a centring and levelling correcting operation in which the centres of the workpiece (100) in first and second planes (108, 102) normal to said predetermined axis (23) and at spaced apart positions therealong are determined and said first and second drive means (62a, 62b; 26x, 26y) are actuated in dependence upon said determination.

Claim 13

Dependent Claim 118 words

Apparatus according to claim 11, characterised in that said program means is operable for controlling said first and second drive means (62a, 62b; 26x, 26y) in dependence upon a first computation in which transverse movement of the workpiece receiving member (4) necessary to bring a first of said workpiece centres into coincidence with said axis (23) is determined; a second computation in which the tilting of the member (4) necessary to bring a line joining said workpiece centres into parallelism with said predetermined axis (23) is determined, and a third computation in which the transverse movement of the member (4) necessary to compensate for displacement of said first workpiece centre as a consequence of said tilting is determined.

Claim 14

Dependent Claim 89 words

Apparatus according to claim 12, characterised in that said program means is operable to perform a centring and levelling sequence in which said first computation is performed and said second drive means (26x, 26y) actuated in accordance therewith to bring said first workpiece centre into coincidence with said predetermined axis (23), and thereafter the position of said second centre is determined, said second and third calculations are performed and said first and second drive means (62a, 62b; 26x, 26y) are actuated in accordance with said second and third calculations.

Claim 15

Dependent Claim 40 words

Apparatus according to claim 13, characterised in that said program means is arranged so that said second drive means (26x, 26y) is actuated in accordance with said second calculation following completion of actuation of said first drive means (62a, 62b).

Claim 16

Dependent Claim 45 words

Apparatus according to claim 13, characterised in that said program means is arranged so that said second drive means (26x, 26y) is actuated in accordance with said third calculation simultaneously with actuation of the first drive means (62a, 62b) in accordance with the second calculation.

Claim 17

Dependent Claim 66 words

Apparatus according to claim 13, characterised in that said programs means is arranged so that said performance of said first, second and third calculations and said actuation of said first and second drive means are carried out such that said first and second drive means (62a, 62b; 26x, 26y) are simultaneously actuated for bringing both of said workpiece centres into coincidence with said predetermined axis (23).

Claim 18

Dependent Claim 59 words

Apparatus according to any preceding claim, characterised in that said program means is further arranged for performing a metrological operation on said workpiece by actuating said third and fourth drive means (74, 76, 78) to cause said sensor to traverse a surface of said workpiece, output signals from said sensor being stored to provide data relating to said surface.

Workpiece position control

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