The present invention relates to a handle feeding control method in a numerical control apparatus having a manual pulse generator (MGP), and a numerical control apparatus. More particularly, this invention relates to a handle feeding control method in a numerical control apparatus in which handle feeding can be performed by controlling a control axis in response to an output pulse signal from a manual pulse generator for generating a pulse signal according to a turning quantity of a manual handle, and a numerical control apparatus.
A numerical control apparatus generally includes, in a console panel, a manual pulse generator for allowing a control axis, which moves a cutting tool or the like, to be manually moved. The manual pulse generator generates a pulse signal according to how much a handle provided with the pulse generator is turned. The numerical control apparatus can control the control axis in response to the pulse signal output from the manual pulse generator, so as to feed the handle.
The handle is fed by a predetermined quantity (for example, 0.001 mm) per pulse output from the manual pulse generator.
The numerical control apparatus includes a magnification selection switch (a manual handle feeding quantity setting switch) concerned in the handle feeding. The magnification selection switch can vary a magnification of a movement quantity per pulse to xc3x9710,xc3x9720, . . . or xc3x97100.
The operator sets the magnification using the magnification selection switch. The operator then turns the manual handle of the manual pulse generator so as to finely adjust the feeding quantity of the cutting tool or the like, and thus, positions the cutting tool or the like at target coordinates.
The numerical control apparatuses provided with such a type of manual pulse generator are disclosed in Japanese Patent Application Laid-Open Nos. 9-16263, 8-339228 and 6-226586.
However, in the conventional numerical control apparatuses, it is necessary to carefully manipulate the handle of the manual pulse generator while visually confirming a value of a current position counter disposed on the console panel or the actual position of the cutting tool or the like in the case where the cutting tool or the like is accurately moved to a predetermined position by turning the manual handle of the manual pulse generator. This imposes many inconveniences on the operator.
Furthermore, if the magnification is increased in order to speedily move the cutting tool or the like so that the manual handle of the manual pulse generator is turned faster, a multiple pulse speed is remarkably increased by the effects of both the high magnification and the large number of pulses per unit period (an interpolation period, hereinafter abbreviated to xe2x80x9can ITPxe2x80x9d) (which may be referred to as xe2x80x9ca pulse speedxe2x80x9d), thereby inducing a markedly high servo motor speed. Sometimes the motor speed exceeds a fast-forward speed as the limit of a feeding speed. Consequently, the multiple pulse speed (obtained by multiplying the pulse speed by the set magnification) is clamped by the fast-forward pulse speed (obtained by dividing the number of pulses by the interpolation period) corresponding to the fast-forward speed so as not to output a command of a feeding speed faster than the fast-forward speed to an axis control circuit.
The fast-forward pulse speed is obtained by converting the fast-forward speed into the pulse speed per interpolation period. Although the feeding speed is clamped by the fast-forward pulse speed in the case where the multiple pulse speed is set in excess of the fast-forward pulse speed, an actual turning quantity of the manual handle of the manual pulse generator is different from an actual movement quantity of the control axis by the number of pulses equivalent to a discarded quantity of speed, with an attendant problem that it is difficult to grasp the precise position of the cutting tool or the like.
Moreover, in the case where the manual handle of the manual pulse generator is abruptly turned fast or is abruptly stopped while it was being turned fast, the control axis is strongly influenced by such an abruptly increased or decreased speed, so that a terrible shock is exerted on the machine tool. Therefore, the operator must pay sufficient attention when manipulating the handle of the manual pulse generator so as to prevent any shock from being exerted on the machine tool, which is disadvantageous.
The present invention has been accomplished in an attempt to solve the above-described problems experienced by the conventional art. It is an object of the present invention to provide the handle feeding control method in the numerical control apparatus which is improved such that positioning by the use of the manual pulse generator, that is, positioning by the handle feeding can be easily and simply performed without any inconvenient operation, a speed increasing or decreasing process concerned in feeding speed control by the handle feeding is precisely performed, a terrible shock can be prevented from being exerted on the machine tool even if the manual handle of the manual pulse generator is abruptly turned at a high speed or is abruptly stopped in the fast turning state, and the numerical control apparatus which is used in carrying out the handle feeding control method.
According to the present invention, in a handle feeding control method in a numerical control apparatus in which a control axis can be controlled in response to a pulse signal output from a manual pulse generator for generating the pulse signal according to the turning quantity of a manual handle so as to perform handle feeding, the handle feeding control method in the numerical control apparatus comprises the steps of: setting and storing at least one of a movement quantity, a target position and a movement range of the control axis; and monitoring the movement quantity or posit ion of the control axis at the time of the handle feeding, and invalidating pulse signals from the manual pulse generator thereafter when the movement quantity or position of the control axis at the time of the handle feeding reaches the limit of the set and stored movement quantity, target position or movement range so as to prevent the movement quantity or position of the control axis at the time of the handle feeding from exceeding the set and stored movement quantity, target position or movement range.
According to the above invention, the pulse signals from the manual pulse generator thereafter are invalidated when the movement quantity or position of the control axis at the time of the handle feeding reaches the limit of the set and stored movement quantity, target position or movement range, so that the movement quantity or position of the control axis at the time of the handle feeding c an be prevented from exceeding the set and stored movement quantity, target position or movement range.
Furthermore, according to the pre sent invention, there is provided a handle feeding control method in a numerical control apparatus in which in the case where handle feeding is performed in the state in which the movement quantity or position of a control axis at the time of the handle feeding reaches the limit of a set and stored movement quantity, target position and movement range, a message indicative of clamping is displayed on a display device.
According to the above invention, in the case where the handle feeding is performed in the state in which the movement quantity or position of the control axis at the time of the handle feeding reaches the limit of the set and stored movement quantity, target position and movement range, the message indicative of the clamping is displayed on the display device, so as to inform an operator of the clamping.
Moreover, according to the present invention, there is provided a handle feeding control method in a numerical control apparatus in which if a pulse speed, which is the number of pulses per unit period of a pulse signal output from a manual pulse generator, exceeds a prescribed fast-forward pulse, an effective pulse speed of axis control is clamped to the fast-forward pulse, the total of short movement quantities caused by the speed clamping is stored, and a control axis can be moved later by the stored total of the short movement quantities.
According to the above invention, if the speed is clamped to cause the short movement quantities, the total of the short movement quantities is stored, and then, the control axis can be moved later by the stored total of the short movement quantities.
Furthermore, according to the present invention, in a numerical control apparatus in which a control axis can be controlled in response to a pulse signal output from a manual pulse generator for generating the pulse signal according to the turning quantity of a manual handle so as to perform handle feeding, the numerical control apparatus comprises: a storage unit for setting and storing at least one of a movement quantity, a target position and a movement range of the control axis; and a movement quantity calculator for monitoring the movement quantity or position of the control axis at the time of the handle feeding, and invalidating pulse signals from the manual pulse generator thereafter when the movement quantity or position of the control axis reaches the limit of the set and stored movement quantity, target position or movement range so as to prevent the movement quantity or position of the control axis at the time of the handle feeding from exceeding the set and stored movement quantity, target position or movement range.
According to the above invention, the pulse signals from the manual pulse generator thereafter are invalidated when the movement quantity or position of the control axis at the time of the handle feeding reaches the limit of the movement quantity, target position or movement range set and stored in the storage unit, so that the movement quantity or position of the control axis at the time of the handle feeding can be prevented from exceeding the set and stored movement quantity, target position or movement range.
Furthermore, according to the present invention, there is provided a numerical control apparatus in which in the case where handle feeding is performed in the state in which the movement quantity or position of a control axis at the time of the handle feeding reaches the limit of the movement quantity, target position or movement range set and stored in the storage unit, a message indicative of clamping is displayed on a display device.
According to the above invention, in the case where the handle feeding is performed in the state in which the movement quantity or position of the control axis at the time of the handle feeding reaches the limit of the set and stored movement quantity, target position and movement range, the message indicative of the clamping is displayed on the display device, so as to inform an operator of the clamping.
Moreover, according to the present invention, there is provided a numerical control apparatus in which if a pulse speed, which is the number of pulses per unit period of a pulse signal output from a manual pulse generator, exceeds a prescribed fast-forward pulse, the movement quantity calculator clamps an effective pulse speed of axis control to the fast-forward pulse, the total of the short movement quantities caused by the speed clamping is stored in the storage unit, and a control axis can be moved later by the total of the short movement quantities stored in the storage unit.
According to the above invention, if the speed is clamped to cause the short movement quantities, the total of the short movement quantities is stored in the storage unit, and then, the control axis can be moved later by the total of the short movement quantities stored in the storage unit.
Furthermore, according to the present invention, in a handle feeding control method in a numerical control apparatus in which a control axis can be controlled in response to a pulse signal output from a manual pulse generator for generating the pulse signal according to the turning quantity of a manual handle so as to perform handle feeding, the handle feeding control method in the numerical control apparatus comprises the steps of: n-dividing the number of pulses per interpolation period of a pulse signal output from the manual pulse generator per interpolation period (wherein n represents an integer of 2 or larger), distributing and outputting the division number of pulses to the interpolation period at the time of inputting of the pulse signal and its following (nxe2x88x921) interpolation periods, and then, endowing the handle feeding with speed increasing/decreasing characteristics.
According to the above invention, the number of pulses per interpolation period of the pulse signal output from the manual pulse generator is n-divided per interpolation period, the division number of pulses is distributed and output to the interpolation period at the time of inputting of the pulse signal and its following (nxe2x88x921) interpolation periods, and then, the handle feeding is endowed with the speed increasing/decreasing characteristics.
Furthermore, according to the present invention, there is provided a handle feeding control method in a numerical control apparatus in which a fraction m (wherein m is an integer smaller than n) produced by the n-division of the number of pulses per interpolation period is output in such a manner as to be respectively distributed to the m interpolation periods out of the n interpolation periods.
According to the above invention, even if the fraction m is produced by the n-division of the number of pulses per interpolation period, the handle feeding can be endowed with the speed increasing/decreasing characteristics.
Moreover, according to the present invention, there is provided a handle feeding control method in a numerical control apparatus in which the division number n of pulses can be arbitrarily varied and set by an operator.
According to the above invention, the division number n of pulses can be arbitrarily varied and set by the operator in conformity with a machine tool.
Furthermore, according to the present invention, there is provided a handle feeding control method in a numerical control apparatus in which the division number n of pulses is an integer obtained by dividing the clamp pulse speed by an allowable maximum increased/decreased speed.
According to the above invention, the division number n of pulses can be set, as a default value, to the integer obtained by dividing the clamp pulse speed by the allowable maximum increased/decreased speed.