Method of correcting positional displacement of machining point

A method of correcting the positional displacement of a machining point in a machine where a delay is caused by a deflection of the machine between a drive point and a machining point of a driven member to which the force of a drive source is applied comprising the steps of:

• predetermining the maximum delay of the machining point with respect to the drive point;
• determining a correction path for correcting said delay in the movement of said drive point after the reversal of moving direction;
• providing memory means for storing a first correction value corresponding to the delay;
• determining, at a reversal of moving direction, a second correction value on the basis of a position in said correction path corresponding to a measured correction path, said maximum delay and a movement command value;
• adding the difference between said first correction value and the second correction value, as stored in said memory means, to the movement command value thereby to output the resultant value as a movement command value;
• updating and storing said second correction value in said memory means;
• and
• outputting said movement command value directly as a movement command value when the absolute value of the first correction value, as stored in said memory means, becomes equal to said maximum delay.

A method of correcting the positional displacement of a machining point, comprising the steps of:

• determining the maximum positional displacement A (A>0) when an actual machining point is positionally displaced by the deflection of a machine with respect to a movement command value of a CNC;
• determining an increment D (D>0) of said movement command value in a second direction up to the point at which the actual positional displacement of the machining point from the point commanded by the movement command of CNC becomes equal to said maximum positional displacement A due to the deflection of the machine after said machining point having moved in a first direction, with said maximum positional displacement A, is stopped by a command and moved in the second direction opposite to said first direction in response to a movement command;
• and
• giving a correction totaling 2A to the movement command during the time period after a reversing command and before the increment of the movement command reaches (D-2A)(D-2A>0), when said machining point moving in an arbitrary direction, with said maximum positional displacement, starts to move in the direction opposite to said one direction in response to the reversing command, wherein
• the point at which the increment of the corrected movement command from the start of the reversed movement becomes equal to said increment D is made to coincide with the point at which the actual machining point starts to be positioned behind by a distance equal to said maximum positional displacement A in the reversed moving direction with respect to said corrected movement command.

An apparatus for correcting the positional displacement of a machining point, comprising:

• a memory storing a first correction value corresponding to a delay;
• a first unit determining, at a reversal of a moving direction, a second correction value on the basis of a position in a correction path corresponding to a measured correction path, a maximum delay and a movement command value;
• and
• a second unit adding the difference between the first and second correction values to the movement command value, and outputting the movement command value when the absolute value of the first correction value becomes equal to the maximum delay.

A method for correcting the positional displacement of a machining point, comprising the steps of:

• storing a first correction value corresponding to a delay;
• determining, at a reversal of a moving direction, a second correction value on the basis of a position in a correction path corresponding to a measured correction path, a maximum delay and a movement command value;
• and
• adding the difference between the first and second correction values to the movement command value, and outputting the movement command value when the absolute value of the first correction value becomes equal to the maximum delay.