System for restoring numerically controlled machine tool to former condition

Claim 2

In a numerical control system for a numerically controlled machine tool in which, when the system is in use a position sensor senses the current position of a movable member or of a drive motor of the machine tool and delivers a current position signal in accordance with said current position, the movable member being positioned on the basis of a commanded position signal and said current position signal, a system for restoring the numerically controlled machine tool to a former condition which comp- ri ses: a non-volatile memory means; means for storing positional control information, which prevails immediately prior to an interruption in electric power, in said non-volatile memory means before the power interruption occurs; means for reading the positional control information'out of said non-volatile memory means when electric power is reintroduced; and means for returning the movable member of the machine tool to the position which said movable member occupied immediately prior to the power interruption, on the basis of said positional control information read out of said non-volatile memory means and said current position signal generated by said position sensor, when the system is in use.

Claim 3

A system according to claim 1, in which the positional control information indicates the current position of the movable member prior to the power interruption when the system is in use.

Claim 4

In a numerical control system for a numerically controlled machine tool in which, when the system is in use, a position sensor senses the current position of a movable member or of a motor of - the machine tool and delivers a current position signal in accordance with said current position, the movable member being positioned on the basis of a commanded position signal and said current position signal, a system for restoring the numerically controlled machine tool to a former condition which comprises: a non-volatile memory means; means for storing (a) positional control information which prevails immediately prior to an interruption in electric power, (b) information specifying the block of numerical control command data read immediately prior to the interruption in electric power, and (c) interpolation information indicating the number of interpolation pulses which were interpolated, up to the point in time immediately prior to the interruption in electric power, or indicating the number of remaining interpolation pulses up to said point in time, in said non-volatile memory means before the power interruption occurs; a volatile memory means; means for transferring to said volatile memory means the information (a), (b) and (c) preserved in said non-volatile memory means when electric power is reintroduced, said information being stored in said volatile memory means; means for returning the movable member of the machine tool to the position which said movable member occupied immediately prior to the power interruption, on the basis of said positional control information transferred to and stored in said volatile memory means and said current position control signal generated by said position sensor; means for executing numerical control processing sequentially from the begining of numerical control command data when the movable member of the machine tool is locked against movement; means for bringing a block of numerical control command data into coincidence with the block of numerical control command data transferred to and stored in said volatile memory means; and means for bringing the number of interpolation pulses interpolated owing to the numerical control command, or the number of remaining internolation pulses, into coincidence with the number of interpdation pulses, or the number of remaining interpiation pulses, transferred to and stored in said volatile memory means; whereby the conditions which prevailed immediately prior to the interruption in electric power may be restored when the system is in use.

Claim 5

In a numerical control system for a numerically controlled machine tool in which, when the system is in use, a position sensor senses the current position of a movable member or of a motor of - the machine tool and delivers a current position signal in accordance with said current position, the movable member being positioned on the basis of a commanded position signal and said current position signal, a system for restoring the numerically controlled machine tool to a former condition which comprises: a non-volatile memory means; means for storing (a) positional control information which prevails immediately prior to an interruption in electric power, (b) information specifying the block of numerical control command data read immediately prior to the interruption in electric power, and (c) interpolation information indicating the number of interpolation pulses which were interpolated, up to the point in time immediately prior to the interruption in electric power, or indicating the number of remaining interpolation pulses up to said point in time, in said non-volatile memory means before the power interruption occurs; a volatile memory means; means for transferring to said volatile memory means the information (a), (b) and (c) preserved in said non-volatile memory means when electric power is reintroduced, said information being stored in said volatile memory means; means for returning the movable member of the machine tool to the position which said movable member occupied immediately prior to the power interruption, on the basis of said positional control information transferred to and stored in said volatile memory means and said current position control signal generated by said position sensor; means for executing numerical control processing sequentially from the begining of numerical control command data when the movable member of the machine tool is locked against movement; means for bringing a block of numerical control command data into coincidence with the block of numerical control command data transferred to and stored in said volatile memory means; and means for bringing the number of interpolation pulses interpolated owing to the numerical control command, or the number of remaining internolation pulses, into coincidence with the number of interpdation pulses, or the number of remaining interpiation pulses, transferred to and stored in said volatile memory means; whereby the conditions which prevailed immediately prior to the interruption in electric power may be restored when the system is in use.

Claim 6

A system according to claim 3, which is adapted for use with an electric discharge machine.

Claim 7

In a numerical control system for a numerically controlled machine tool in which, when the system is in use, a position sensor senses the current position of a movable member or of a drive motor of the machine tool and delivers a current position signal in accordance with said current position, the movable member being positioned on the basis of a commanded position signal and said current position signal, a system for restoring the numerically controlled machine tool to a former condition which comprises: retrieval means for retrieving the beginning of numerical control command data; automatic power introduction means for introducing electric power to the numerical control system automatically after the restoration of electric power from a main power supply following the interruption of said electric power; non-volatile memory means; means for storing (a) positional control information which prevails immediately prior to an interruption in electric power, (b) information specifying the block of numerical control command data read immediately prior to the interruption in electric power, and (c) interpolation information indicating the number of interpolation pulses which were interpdated, up to the point in time immediately prior to the interruption in electric power, or indicating the number of remaining interpolation pulses up to said point in time, in said non-volatile memory means before the power interruption occurs; means for recovering the information (a), (b) and (c) preserved in said non-volatile memory means when electric power is introduced; means for returning the movable member of the machine tool to the position which said movable member occupied immediately prior to the power interruption, on the basis of said recovered positional control information and said current position control signal generated by said position sensor; means for executing numerical control processing sequentially from the beginning of the numerical control command data, retrieved by said retrieval means, when the movable member of the machine tool is locked against movement; means for bringing a block of numerical control command data into coincidence with the recovered block of numerical command control data; and means for bringing the number of interpolation pulses interpolated owing to the numerical control command, or the number of remaining interpolation pulses, into coincidence with the recovered number of interpolation pulses, or the recovered number of remaining interpolation pulses; whereby the conditions which prevailed immediately prior to the interruption in electric power may be restored when the system is in use.

Claim 8

In a numerical control system for a numerically controlled machine tool in which, when the system is in use, a position sensor senses the current position of a movable member or of a drive motor of the machine tool and delivers a current position signal in accordance with said current position, the movable member being positioned on the basis of a commanded position signal and said current position signal, a system for restoring the numerically controlled machine tool to a former condition which comprises: retrieval means for retrieving the beginning of numerical control command data; automatic power introduction means for introducing electric power to the numerical control system automatically after the restoration of electric power from a main power supply following the interruption of said electric power; non-volatile memory means; means for storing (a) positional control information which prevails immediately prior to an interruption in electric power, (b) information specifying the block of numerical control command data read immediately prior to the interruption in electric power, and (c) interpolation information indicating the number of interpolation pulses which were interpdated, up to the point in time immediately prior to the interruption in electric power, or indicating the number of remaining interpolation pulses up to said point in time, in said non-volatile memory means before the power interruption occurs; means for recovering the information (a), (b) and (c) preserved in said non-volatile memory means when electric power is introduced; means for returning the movable member of the machine tool to the position which said movable member occupied immediately prior to the power interruption, on the basis of said recovered positional control information and said current position control signal generated by said position sensor; means for executing numerical control processing sequentially from the beginning of the numerical control command data, retrieved by said retrieval means, when the movable member of the machine tool is locked against movement; means for bringing a block of numerical control command data into coincidence with the recovered block of numerical command control data; and means for bringing the number of interpolation pulses interpolated owing to the numerical control command, or the number of remaining interpolation pulses, into coincidence with the recovered number of interpolation pulses, or the recovered number of remaining interpolation pulses; whereby the conditions which prevailed immediately prior to the interruption in electric power may be restored when the system is in use.

Claim 9

A system according to claim 5, in which the positional control information indicates the current position of the movable member prior to the power interruption.

Claim 10

. A system according to claim 5, which is adapted for use with an electric discharge machine.

Claim 11

A system according to claim 5, in which an identifying code is attached to the beginning of numerical control command data.

Claim 12

A system according to claim 1 or 2, and comprising automatic power introduction means for introducing electric power to the numerical control system automatically after the restoration of electric power from a main power supply following the interruption of said electric power.

Claim 13

A system according to claim 1, 2,8 or 9, which is adapted for use with an electric discharge machine.