Replacement path machining method and apparatus

1. A method of machining a workpiece ( 2 ), the method comprising:

specifying a tool path for a cutting tool, the tool path being a unidirectional path along which the cutting tool is to be moved during machining of the workpiece ( 2 ), wherein the tool path comprises a plurality of pre-identified tool path segments ( 26 , 28 , 30 );

defining, for each tool path segment ( 26 , 28 , 30 ), an entry point, wherein the entry point of a tool path segment ( 26 , 28 , 30 ) is a point on that tool path segment ( 26 , 28 , 30 ), through which the tool enters and does not exit the respective tool path segment ( 26 , 28 , 30 );

defining, for each tool path segment ( 26 , 28 , 30 ), an entry path ( 32 , 34 , 36 ), wherein the entry path ( 32 , 34 , 36 ) of a tool path segment ( 26 , 28 , 30 ) is a path for the cutting tool from a point that is remote from the workpiece ( 2 ) to the entry point of that tool path segment ( 26 , 28 , 30 );

specifying a sequence comprising a plurality of machining points along the tool path, each machining point being a point along the tool path at which a respective feature ( 20 , 22 , 24 ) is to be machined into the workpiece ( 2 ), wherein each tool path segment ( 26 , 28 , 30 ) includes one or more machining points;

moving a first cutting tool ( 6 ) along the tool path from a first point on the tool path to a second point on the tool path;

as the first cutting tool ( 6 ) is moved from the first point to the second point, machining, by the first cutting tool ( 6 ), the workpiece ( 2 ), for each of the machining points the first cutting tool ( 6 ) is moved to, controlling the first cutting tool ( 6 ) to machine the corresponding feature ( 20 , 22 , 24 ) into the workpiece ( 2 );

for each machining point, assigning, to that machining point, either a first label or a second label, wherein the first label is assigned to a machining point if the feature ( 20 , 22 , 24 ) corresponding to that machining point has not been machined, and the second label is assigned to a machining point if the feature ( 20 , 22 , 24 ) corresponding to that machining point has been machined;

after the first cutting tool ( 6 ) has been moved to the second point, moving the first cutting tool ( 6 ) to a point remote from the workpiece ( 2 ), identifying the first machining point in the sequence to which the first label has been assigned;

moving a second cutting tool ( 18 ) along the entry path ( 32 , 34 , 36 ) of the tool path segment ( 26 , 28 , 30 ) containing the identified machining point, in which the second point is located, from a point that is remote from the workpiece ( 2 ) to the entry point of the tool path segment ( 26 , 28 , 30 ) containing the identified machining point, in which the second point is located; and

moving the second cutting tool ( 18 ) along the tool path from the entry point of the tool path segment ( 26 , 28 , 30 ) in which the second point is located to the second point.

2. The method according to claim 1 , the method further comprising, thereafter, resuming a machining operation by moving the second cutting tool ( 18 ) along the tool path and machining, by the second cutting tool ( 18 ), the workpiece ( 2 ).

3. The method according to claim 1 , wherein the step of moving the second cutting tool ( 18 ) along the tool path from the entry point of the tool path segment ( 26 , 28 , 30 ) in which the second point is located to the second point is performed without the second cutting tool ( 18 ) machining the workpiece ( 2 ).

4. The method according to claim 1 , wherein the first cutting tool ( 6 ) is a different cutting tool ( 6 ) to the second cutting tool ( 18 ).

5. The method according to claim 1 , wherein the workpiece ( 2 ) is an aircraft panel.

6. The method according to claim 1 , the method further comprising, after the first cutting tool ( 6 ) has been moved to the point remote from the workpiece ( 2 ), replacing the first cutting tool ( 6 ) with the second cutting tool ( 18 ).

7. The method according to claim 1 , wherein moving the second cutting tool ( 18 ) along the tool path from the entry point of the tool path segment ( 26 , 28 , 30 ) in which the second point is located to the second point comprises moving the second cutting tool ( 18 ) along the tool path from the entry point of the tool path segment ( 26 , 28 , 30 ) containing the identified machining point to the identified machining point.

8. The method according to claim 1 , wherein:

the method further comprises specifying a sequence comprising a plurality of machining points along the tool path, each machining point being a point along the tool path at which a respective feature ( 20 , 22 , 24 ) is to be machined into the workpiece ( 2 ), wherein each tool path segment ( 26 , 28 , 30 ) includes one or more machining points;

the step of machining, by the first cutting tool ( 6 ), the workpiece ( 2 ) includes, for each of the machining points the first cutting tool ( 6 ) is moved to, controlling the first cutting tool ( 6 ) to machine the corresponding feature ( 20 , 22 , 24 ) into the workpiece ( 2 ); and

the method further comprises, for each tool path segment ( 26 , 28 , 30 ), assigning, to that tool path segment ( 26 , 28 , 30 ), either a third label or a fourth label, wherein the third label is assigned to a tool path segment ( 26 , 28 , 30 ) if the feature ( 20 , 22 , 24 ) corresponding to one or more of the machining points in that tool path segment ( 26 , 28 , 30 ) has not been machined, and the fourth label is assigned to a tool path segment ( 26 , 28 , 30 ) if the features ( 20 , 22 , 24 ) corresponding every machining point in that tool path segment ( 26 , 28 , 30 ) have been machined;

the method further comprises, after the first cutting tool ( 6 ) has been moved to the second point, identifying the first tool path segment ( 26 , 28 , 30 ) in the sequence to which the third label has been assigned; and

the step of moving the second cutting tool ( 18 ) along the entry path ( 32 , 34 , 36 ) of the tool path segment ( 26 , 28 , 30 ) in which the second point is located comprises moving the second cutting tool ( 18 ) along the entry path ( 32 , 34 , 36 ) of the identified tool path segment ( 26 , 28 , 30 ).

9. The method according to claim 1 , the method further comprising:

after the first cutting tool ( 6 ) has been moved to the second point, determining that a tool life of the first cutting tool ( 6 ) is equal to a predetermined threshold value; and

responsive to determining that a tool life of the first cutting tool ( 6 ) is equal to a predetermined threshold value, preventing further machining of the workpiece ( 2 ) using the first cutting tool ( 6 ).

10. The method according to claim 1 , the method further comprising:

defining, for each tool path segment ( 26 , 28 , 30 ), an exit point, wherein the exit point of a tool path segment ( 26 , 28 , 30 ) is a point on that tool path segment ( 26 , 28 , 30 ), through which the tool exits and does not enter the respective tool path segment ( 26 , 28 , 30 ), and wherein the exit point of a tool path segment is located at a last machining point within that tool path segment;

defining, for each tool path segment ( 26 , 28 , 30 ), an exit path, wherein the exit path of a tool path segment ( 26 , 28 , 30 ) is a path for a cutting tool ( 6 ) from the exit point of that tool path segment ( 26 , 28 , 30 ) to a point that is remote from the workpiece ( 2 );

performing a machining process including moving the cutting tool ( 6 ) along at least part of the tool path and machining, by the cutting tool ( 6 ), the workpiece ( 2 ); and, after the first cutting tool ( 6 ) has been moved to the second point, interrupting the machining process and moving the first cutting tool ( 6 ) along a current tool path segment ( 26 , 28 , 30 ) without machining the workpiece ( 2 ), from the second point to the exit point of the current tool path segment ( 26 , 28 , 30 ); and

moving the first cutting tool ( 6 ) along the exit path of the current tool path segment ( 26 , 28 , 30 ).

11. An aircraft component machined using a method comprising:

specifying a tool path for a cutting tool, the tool path being a unidirectional path along which the cutting tool is to be moved during machining of the aircraft component, wherein the tool path comprises a plurality of pre-identified tool path segments ( 26 , 28 , 30 );

defining, for each tool path segment ( 26 , 28 , 30 ), an entry point, wherein the entry point of a tool path segment ( 26 , 28 , 30 ) is a point on that tool path segment ( 26 , 28 , 30 ), through which the tool enters and does not exit the respective tool path segment ( 26 , 28 , 30 );

defining, for each tool path segment ( 26 , 28 , 30 ), an entry path ( 32 , 34 , 36 ), wherein the entry path ( 32 , 34 , 36 ) of a tool path segment ( 26 , 28 , 30 ) is a path for the cutting tool from a point that is remote from the aircraft component to the entry point of that tool path segment ( 26 , 28 , 30 );

specifying a sequence comprising a plurality of machining points along the tool path, each machining point being a point along the tool path at which a respective feature ( 20 , 22 , 24 ) is to be machined into the aircraft component, wherein each tool path segment ( 26 , 28 , 30 ) includes one or more machining points;

moving a first cutting tool ( 6 ) along the tool path from a first point on the tool path to a second point on the tool path;

as the first cutting tool ( 6 ) is moved from the first point to the second point, machining, by the first cutting tool ( 6 ), aircraft component, for each of the machining points the first cutting tool ( 6 ) is moved to, controlling the first cutting tool ( 6 ) to machine the corresponding feature ( 20 , 22 , 24 ) into the aircraft component;

for each machining point, assigning, to that machining point, either a first label or a second label, wherein the first label is assigned to a machining point if the feature ( 20 , 22 , 24 ) corresponding to that machining point has not been machined, and the second label is assigned to a machining point if the feature ( 20 , 22 , 24 ) corresponding to that machining point has been machined;

after the first cutting tool ( 6 ) has been moved to the second point, moving the first cutting tool ( 6 ) to a point remote from the aircraft component, identifying the first machining point in the sequence to which the first label has been assigned;

moving a second cutting tool ( 18 ) along the entry path ( 32 , 34 , 36 ) of the tool path segment ( 26 , 28 , 30 ) containing the identified machining point, in which the second point is located, from a point that is remote from the aircraft component to the entry point of the tool path segment ( 26 , 28 , 30 ) containing the identified machining point, in which the second point is located; and

moving the second cutting tool ( 18 ) along the tool path from the entry point of the tool path segment ( 26 , 28 , 30 ) in which the second point is located to the second point.

12. Apparatus for machining a workpiece ( 2 ), the apparatus comprising:

a first cutting tool ( 6 );

a second cutting tool ( 18 );

one or more processors ( 10 ) configured to:

store a tool path for a cutting tool ( 6 ), the tool path being a unidirectional path along which a cutting tool is to be moved during machining of the workpiece ( 2 ), wherein the tool path comprises a plurality of pre-identified tool path segments ( 26 , 28 , 30 ), each tool path segment ( 26 , 28 , 30 ) comprising an entry point, wherein the entry point of a tool path segment ( 26 , 28 , 30 ) is a point on that tool path segment ( 26 , 28 , 30 ), through which the tool enters and does not exit the respective tool path segment ( 26 , 28 , 30 ); and

store, for each tool path segment ( 26 , 28 , 30 ), an entry path ( 32 , 34 , 36 ), wherein the entry path ( 32 , 34 , 36 ) of a tool path segment ( 26 , 28 , 30 ) is a path for the cutting tool from a point that is remote from the workpiece ( 2 ) to the entry point of that tool path segment ( 26 , 28 , 30 );

specify a sequence comprising a plurality of machining points along the tool path, each machining point being a point along the tool path at which a respective feature ( 20 , 22 , 24 ) is to be machined into the workpiece ( 2 ), wherein each tool path segment ( 26 , 28 , 30 ) includes one or more machining points; and

a controller ( 8 ) configured to:

move a first cutting tool ( 6 ) along the tool path from a first point on the tool path to a second point on the tool path;

as the first cutting tool ( 6 ) is moved from the first point to the second point, machine, using the first cutting tool ( 6 ), the workpiece ( 2 ), for each of the machining points the first cutting tool ( 6 ) is moved to, control the first cutting tool ( 6 ) to machine the corresponding feature ( 20 , 22 , 24 ) into the workpiece ( 2 );

for each machining point, assign, to that machining point, either a first label or a second label, wherein the first label is assigned to a machining point if the feature ( 20 , 22 , 24 ) corresponding to that machining point has not been machined, and the second label is assigned to a machining point if the feature ( 20 , 22 , 24 ) corresponding to that machining point has been machined;

after the first cutting tool ( 6 ) has been moved to the second point, move the first cutting tool ( 6 ) to a point remote from the workpiece ( 2 ), identify the first machining point in the sequence to which the first label has been assigned;

move a second cutting tool ( 18 ) along the entry path ( 32 , 34 , 36 ) of the tool path segment ( 26 , 28 , 30 ) containing the identified machining point in which the second point is located from a point that is remote from the workpiece ( 2 ) to the entry point of the tool path segment ( 26 , 28 , 30 ) containing the identified machining point in which the second point is located; and

move the second cutting tool ( 18 ) along the tool path from the entry point of the tool path segment ( 26 , 28 , 30 ) in which the second point is located to the second point.

13. A non-transient machine readable storage medium storing a program or at least one of the plurality of programs arranged such that when executed by a computer system or one or more processors it/they cause the computer system or the one or more processors to operate in accordance with a method of machining a workpiece ( 2 ) comprising:

specifying a tool path for a cutting tool, the tool path being a unidirectional path along which the cutting tool is to be moved during machining of the workpiece ( 2 ), wherein the tool path comprises a plurality of pre-identified tool path segments ( 26 , 28 , 30 );

defining, for each tool path segment ( 26 , 28 , 30 ), an entry point, wherein the entry point of a tool path segment ( 26 , 28 , 30 ) is a point on that tool path segment ( 26 , 28 , 30 ), through which the tool enters and does not exit the respective tool path segment ( 26 , 28 , 30 );

defining, for each tool path segment ( 26 , 28 , 30 ), an entry path ( 32 , 34 , 36 ), wherein the entry path ( 32 , 34 , 36 ) of a tool path segment ( 26 , 28 , 30 ) is a path for the cutting tool from a point that is remote from the workpiece ( 2 ) to the entry point of that tool path segment ( 26 , 28 , 30 );

specifying a sequence comprising a plurality of machining points along the tool path, each machining point being a point along the tool path at which a respective feature ( 20 , 22 , 24 ) is to be machined into the workpiece ( 2 ), wherein each tool path segment ( 26 , 28 , 30 ) includes one or more machining points;

moving a first cutting tool ( 6 ) along the tool path from a first point on the tool path to a second point on the tool path;

as the first cutting tool ( 6 ) is moved from the first point to the second point, machining, by the first cutting tool ( 6 ), the workpiece ( 2 ), for each of the machining points the first cutting tool ( 6 ) is moved to, controlling the first cutting tool ( 6 ) to machine the corresponding feature ( 20 , 22 , 24 ) into the workpiece ( 2 );

for each machining point, assigning, to that machining point, either a first label or a second label, wherein the first label is assigned to a machining point if the feature ( 20 , 22 , 24 ) corresponding to that machining point has not been machined, and the second label is assigned to a machining point if the feature ( 20 , 22 , 24 ) corresponding to that machining point has been machined;

after the first cutting tool ( 6 ) has been moved to the second point, moving the first cutting tool ( 6 ) to a point remote from the workpiece ( 2 ), identifying the first machining point in the sequence to which the first label has been assigned;

moving a second cutting tool ( 18 ) along the entry path ( 32 , 34 , 36 ) of the tool path segment ( 26 , 28 , 30 ) containing the identified machining point, in which the second point is located, from a point that is remote from the workpiece ( 2 ) to the entry point of the tool path segment ( 26 , 28 , 30 ) containing the identified machining point, in which the second point is located; and

moving the second cutting tool ( 18 ) along the tool path from the entry point of the tool path segment ( 26 , 28 , 30 ) in which the second point is located to the second point.