Numerical controller

#1. Field of the Invention

#The invention relates to a numerical controller for controlling an industrial machine such as a machine tool and a manufacturing machine, and in particular to a path-table operation, i.e. so-called electronic cam control in which axes of the machine are controlled to be synchronized by the numerical controller.

#2. Description of Related Art

#FIG. 1 is a functional diagram schematically showing a path table operation process performed by a numerical controller according to an embodiment of the present invention;

#FIG. 2 is a diagram of a motion pattern of a controlled axis based on a path-table operation data table shown in FIG. 3;

#FIG. 3 is an example of a path-table operation data table;

#FIG. 1 is a functional diagram of a path-table operation according to an embodiment of the invention. In FIG. 1, a reference pulse signal representing motion of a reference axis, such as a pulse signal from a position coder provided at a spindle or from an external reference pulse generator, is inputted to a counter 1 and the number of pulses of the reference pulse signal is counted by the counter 1 at every predetermined processing period (ITP). A multiplier 2 multiplies the number of pulses counted by the counter 1 by a scale factor set by override means, and result of the multiplication is stored in a reference position counter 3. The reference position counter 3 is reset when a path-table operation function is commanded or when a one-rotation signal is issued from the position coder for the reference axis for the first time after a path-table operation function is commanded. Thus, the reference position counter 3 stores the position of the reference axis altered by the multiplication by the override factor.

#The value of the reference position counter 3 (hereinafter referred to as reference position”) is respectively inputted to path-table operation interpolation sections 4x, 4z provided for respective controlled axes (in the present embodiment, X-axis and Z-axis). Referring to path-table operation data tables Tx, Tz stored in a memory for the respective controlled axes, respective command positions of the controlled axes with respect to the reference-axis position are obtained, and motion commands of a difference between the command position obtained in the present processing period and the command position in the last processing period are outputted to motors 5x, 5z for the controlled axes respectively.

#The path-table operation is performed as above. Thus, when the scale factor set by the override means is “1”, the number of pulses of the reference pulse signal counted by the counter 1 is stored in the reference position counter 3 as the reference position, and the controlled axes are operated in synchronism with the reference axis in the same manner as the conventional manner. If the reference pulse signal is generated by a position coder attached to the spindle, the controlled axes (X-axis and Z-axis) move in synchronization with the spindle and also in synchronization with each other. When the scale factor is changed by the override means to, for example, “0.5”, the controlled axes move at a speed which corresponds to half the rotating speed of the spindle. Thus, by changing the value of the override factor, the controlled axes (X-axis and Z-axis) can be driven in the path-table operation in synchronism with the reference axis (spindle), at a desired speed not restricted by the speed of the reference axis.