JP2000225524A - Shaft feeding thrust assisting method for linear motor driving electric discharge machining device and linear motor driving electric discharge machining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent couple of forces from working on a shaft feeding mechanism by providing an air cylinder on a center axis of driving thrust of a linear motor working on a quill and directly acting pulling up force of the air cylinder on the same axis as the center axis. SOLUTION: When an air cylinder 61 is utilized as an auxiliary thrust source and air pressure of an air cylinder 61 is set so as not to move a quill 81 by gravity of a body part to be moved including an electrode of a working head during a preparing work, the quill 81 does not fall in a lower direction and does not damage a machine device, even if magnetic force for holding position between a stator 10 and a moving element 8 is not generated, regardless of a position of the quill 81. Because this thrust is always kept during a moving, weight of a body to be moved of a working head 7 is not excessively applied as load at the time of moving of the quill 81. Because thrust of the air cylinder 61 is provided so as to work on a center of the moving element 8, an anxiety of bending moment is eliminated and linearity of a shaft feeding device is also kept.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for assisting a driving force of an electric discharge machine in which a machining head is axially fed by a linear motor, and an electric discharge machine driven by a linear motor. In particular, a thrust assisting method for a linear motor drive type electric discharge machine capable of reducing the load on a linear motor while maintaining high responsiveness by applying an appropriate assisting thrust to a shaft feeder of a machining head including a quill. And an electric discharge machine driven by a linear motor.

[0002]

2. Description of the Related Art An electrode as a tool is provided at a position facing a workpiece, and a predetermined machining voltage is applied to a machining gap formed between the workpiece and the electrode to generate an intermittent discharge. There is known an electric discharge machining apparatus for machining a workpiece into a desired hole shape. In electrical discharge machining, generally, a workpiece is placed on a horizontal processing table such that the processing surface of the workpiece is positioned on the upper side, and at least the electrode is oriented in a direction of a machining hole, that is, a direction perpendicular to the machining surface (hereinafter, referred to as a vertical direction). , Z-axis direction), the electrode is attached to a shaft feeder that moves in the Z-axis direction, and processing is performed while controlling the position of the electrode.

[0003] Discharge machining is different from cutting in general machine tools and the like, in which an electrode or a workpiece is moved relatively close to and retracted from the other so as to maintain a machining gap at a predetermined distance. Servo control must be performed. It is desirable that this servo operation be performed at a higher speed and with a higher response. In addition, in the sinking electric discharge machining, the machining is performed while performing a so-called jump operation in which the electrode approaches and retreats from the workpiece in order to promote the discharge of machining waste from the machining hole. It is desirable that this control be performed at a higher speed and with higher response.

Heretofore, a Z-axis direction feeder of an electric discharge machine has been provided with an axial feeder of a type in which a quill or a slider is linearly moved in a Z-axis direction by a rotary motor via a ball screw. Was common,
In recent years, Japanese Patent Laid-Open No. 5-104332 proposes an electric discharge machine equipped with a drive type shaft feeder using a linear motor as a shaft feed drive source instead of a rotary motor as a shaft feed drive source. This method does not require a mechanism for transmitting the rotary motion to the linear motion, so there is no backlash or a spring element of the member, and there is an advantage that a higher-speed and higher-response axial feed can be performed. However, the EDM equipped with such a linear motor type axis feeder,
Due to the structure of the linear motor, the Z-axis feed mechanism must be held by the thrust of the linear motor, and it is necessary to generate a larger holding force than the conventional rotary motor system.

Therefore, in Japanese Patent Application Laid-Open No. Hei 8-309620, a wire rope is connected to a processing head, and the wire rope is guided to the opposite side of the processing head via a pulley, as has been conventionally performed. To reduce the load on the linear motor by using a configuration that balances the processing head by providing a counterbalance by suspending a weight that weighs the weight of the processing head considering the electrode weight at the other end of the Is disclosed.

[0006]

However, in an electric discharge machine employing a linear motor and a shaft feeder, the source of the balance force must not impair the high response of the linear motor. In addition, it is necessary to be able to follow a high-acceleration movement operation required when performing a high-speed jump operation for dramatically improving the processing speed.

For this reason, in a configuration in which a wire rope is connected to the processing head, and a weight that weighs the weight of the processing head in consideration of the electrode weight is suspended from the other end of the wire rope via a pulley, It cannot follow the movement of the robot and is difficult to adopt.

Therefore, it is possible to hold the processing head by the thrust of the linear motor without imparting a balance force as described above. However, a high-output linear motor taking into account the weight of the processing head can be used. Not only is it necessary, but if the thrust continues to be generated even during standstill, there is a problem of thermal displacement of the mechanical part due to the heat generated by the exciting coil. This causes a problem that the performance is reduced.

In the electric discharge machining, the shape of the machining electrode is also various, and the same electric discharge machining apparatus such as machining with a fine electrode having an electrode diameter of about 0.01 mm, rib machining of a plastic mold, machining with a relatively large machining area, and the like. Various processes are performed on the above. For this reason, it is not sufficient for the thrust assisting device used in the electric discharge machine to simply balance the weight of the machining head. This is because the performance and characteristics required of the feed device of the processing head are different when performing various types of processing as described above. For example, when processing with a fine processing electrode or when processing a small object with a processing current of about 1 to 5 A, high responsiveness is required especially for axial feed, and high acceleration jump operation is required for deep rib processing. In addition, in machining with a large machining area, a large lifting force that can counteract the negative pressure acting on the electrode when the electrode is lifted in a jump operation is required. In addition, it is necessary to reduce the load on the linear motor as much as possible when stationary other than during machining, and to always generate an auxiliary thrust so that the machining head does not drop in the event of a power failure or emergency stop.

In view of the above, the present invention makes use of the advantages of a shaft feeder driven by a linear motor, and reduces the machining performance of the shaft feeder without changing the operation state and machining form of the electric discharge machine. It is an object of the present invention to provide a shaft feed thrust assisting method and a linear motor driven electric discharge machine in a linear motor drive type electric discharge machine capable of applying a suitable auxiliary thrust to a moving object of the shaft feeder.

[0011]

According to a first aspect of the present invention, there is provided a thrust assisting method according to the first aspect of the present invention, wherein the thrust assisting method includes a numerical controller for performing a relative movement operation between an electrode and a workpiece by a linear motor. In the axial feed thrust assisting method of processing equipment,
A moving body configured as a mover of a linear motor is provided so as to be movable in a vertical direction with respect to a processing table, and an air cylinder thrust acts directly on a substantially central axis of an axial driving thrust acting on the moving body. In at least one stage of an operation state such as power-on of the electric discharge machining device, replacement of electrodes, NC program operation or electric discharge machining, the air cylinder is supplied with air at a required pressure to the air cylinder. This is a thrust assisting method of a linear motor driven electric discharge machine for applying a required assisting thrust according to an operation state to a moving object.

According to the thrust assisting method of the linear motor drive electric discharge machine according to the present invention, the quill of the machining head is constituted as a movable element of the linear motor, and the quill of the linear motor acting on the quill is substantially on the center axis of the thrust. To provide a pulling force of the air cylinder directly substantially coaxially with the axis, to prevent a couple from acting on the shaft feed mechanism,
The air pressure supplied to the air cylinder according to the operation state of the electric discharge machine during machining preparation work after turning on the power of the electric discharge machine or after replacement of the electrode and during NC program operation or electric discharge machining, as an appropriate air pressure, The pulling force generated by the air cylinder is constantly applied to the quill, and the auxiliary thrust according to the operation state reduces the load on the linear motor, and the output of the linear motor is effectively used as the driving force of the shaft feeder.

According to a second aspect of the present invention, there is provided a thrust assisting method according to the present invention, wherein an axial feed of an electric discharge machining apparatus provided with a numerical controller for performing a relative movement operation between an electrode and a workpiece by a linear motor. In the thrust assisting method, on a substantially central axis of an axial driving thrust acting on a moving body configured as a movable element of a linear motor provided to be movable in a vertical direction with respect to a processing table on which a workpiece is mounted. The thrust of the air cylinder is arranged to act directly, and at least one stage of the operation state such as power-on of the electric discharge machine, exchange of electrodes, NC program operation or electric discharge machining, the linear motor drive device The current command value is read, and a pressure setting signal is output to the supply pressure setting device of the air cylinder so that the current command value substantially matches the current reference value stored in advance. Wherein by supplying air of required pressure in the cylinder is thrust assist method of the linear motor drive electric discharge machining apparatus for imparting a required auxiliary thrust in accordance with the operating state to be mobile.

According to the thrust assisting method of the linear motor drive electric discharge machine of the present invention, the quill of the machining head is constituted as a movable element of the linear motor, and the quill of the linear motor acting on the quill is substantially on the center axis of the thrust. To provide a pulling force of the air cylinder directly substantially coaxially with the axis, to prevent a couple from acting on the shaft feed mechanism,
The current command value of the linear motor driving device is read in accordance with the operation state of the electric discharge machining device such as during the machining preparation work after the power supply of the electric discharge machining device or after the replacement of the electrode and during the operation of the NC program or the electric discharge machining. The air pressure supplied to the air cylinder is automatically adjusted to an appropriate air pressure so that the current command value substantially matches the current reference value stored in advance, and the pulling force generated by the air cylinder is always applied to the quill for operation. The auxiliary thrust according to the state reduces the load on the linear motor, and the output of the linear motor is effectively used as the driving force of the shaft feeder.

According to a third aspect of the present invention, there is provided a thrust assisting method according to the present invention, wherein an axial feed of an electric discharge machining apparatus provided with a numerical controller for performing a relative movement operation of an electrode and a workpiece by a linear motor. In the thrust assisting method, on a substantially central axis of an axial driving thrust acting on a moving body configured as a movable element of a linear motor provided to be movable in a vertical direction with respect to a processing table on which a workpiece is mounted. A required reference thrust value is stored in response to at least one of a power-on signal, an electrode replacement signal, an NC program operation start signal, or a machining start signal of the electric discharge machine, arranged so that the thrust of the air cylinder acts directly. Calling from a device, reading a current command value from a linear motor drive control device, obtaining a deviation between the reference thrust value and a current command value, A step of outputting a pressure setting signal to the supply pressure setting means in accordance with the above, until the reference thrust value and the current command value match, and the deviation value obtained by repeating the calling step, the reading step, and the step of obtaining the deviation. Is output to a supply pressure setting means to set a cylinder pressure of an air cylinder to apply a required auxiliary thrust to the moving object.

According to the thrust assisting method of the linear motor drive electric discharge machine of the present invention, the quill of the machining head is constituted as a movable element of the linear motor, and the quill of the linear motor acting on the quill is substantially on the center axis. To provide a pulling force of the air cylinder directly substantially coaxially with the axis, to prevent a couple from acting on the shaft feed mechanism,
The current command value of the linear motor driving device is read in accordance with the operation state of the electric discharge machining device such as during the machining preparation work after the power supply of the electric discharge machining device or after the replacement of the electrode and during the operation of the NC program or the electric discharge machining. The air pressure supplied to the air cylinder is automatically adjusted to an appropriate air pressure so that the current command value substantially matches the current reference value stored in advance, and the pulling force generated by the air cylinder is always applied to the quill. The auxiliary thrust according to the operation state reduces the load on the linear motor, and the output of the linear motor is effectively used as the driving force of the shaft feeder.

According to a fourth aspect of the present invention, there is provided a thrust assisting method according to the present invention, wherein an axial feed of an electric discharge machining apparatus provided with a numerical controller for performing a relative movement operation between an electrode and a workpiece by a linear motor. In the thrust assisting method, on a substantially central axis of an axial driving thrust acting on a moving body configured as a movable element of a linear motor provided to be movable in a vertical direction with respect to a processing table on which a workpiece is mounted. Arranging the thrust of the air cylinder to act directly, reading the position deviation value of the moving object from the linear motor drive control device at the time of NC program operation or electric discharge machining, and reading the read position deviation value. Comparing with a predetermined position deviation value, outputting a signal for increasing the supply pressure to the air cylinder to the supply pressure setting means when the position deviation value is equal to or more than the predetermined value, Wherein by changing the cylinder pressure in the cylinder is thrust assist method of the linear motor driving the electric discharge machining apparatus comprising a step of imparting a required auxiliary thrust to be mobile.

According to the thrust assisting method of the linear motor drive electric discharge machine of the present invention, the quill of the machining head is constituted as a movable element of the linear motor, and the quill of the quill is substantially on the center axis of the driving thrust of the linear motor acting on the quill. An air cylinder is provided to directly apply the pulling force of the air cylinder substantially coaxially with the axis to prevent a couple from acting on the shaft feed mechanism. The value is read from the linear motor drive control device, and the read position deviation value is compared with a predetermined position deviation value. When the position deviation value is equal to or larger than the predetermined value, the supply pressure to the air cylinder is increased.
As the supply pressure increases, the pulling force generated by the air cylinder increases, and an auxiliary thrust against the negative pressure acting on the moving object is given. The auxiliary thrust compensates for the shortage of the thrust of the linear motor, and the output of the linear motor is effectively used as the driving force of the shaft feeder, and the quill is quickly jumped.

According to a fifth aspect of the present invention, there is provided a thrust assisting method according to the present invention, wherein a working head for mounting a working electrode is directly suspended by an air cylinder so as to be axially fed, and the electrode and the work to be processed are suspended. In the axial feed thrust assisting method for an electric discharge machine provided with a numerical controller for performing a relative movement operation of an object by a linear motor, a step of setting and inputting a required auxiliary thrust according to a machining mode or an operation state of the electric discharge machine. Calling an auxiliary thrust value stored in a storage device corresponding to the input value; outputting a pressure setting signal to a supply pressure setting means based on the called auxiliary thrust value; Changing the supply pressure to substantially match the thrust value, and supplying the air pressure changed in the step to the air cylinder to generate a required auxiliary thrust. Tsu running and flop, a thrust assist method of the linear motor drive electric discharge machining apparatus for imparting a required auxiliary thrust movable body of the shaft feeder.

According to the thrust assisting method of the linear motor drive electric discharge machine of the present invention, the quill of the machining head is constituted as a movable element of the linear motor, and the quill of the quill is substantially on the center axis of the driving thrust of the linear motor acting on the quill. An air cylinder is provided to directly apply the pulling force of the air cylinder substantially coaxially with the axis to prevent a couple from acting on the shaft feed mechanism. A required auxiliary thrust according to the machining mode or operation state of the electric discharge machine is set and input, an auxiliary thrust value corresponding to the input value stored in advance is called, and pressure is supplied to the supply pressure setting means based on the auxiliary thrust value. Output the setting signal. The supply pressure of the air cylinder is adjusted to an appropriate air pressure based on the thrust value, and the pulling force generated by the air cylinder is constantly applied to the quill, and the auxiliary thrust according to the operation state reduces the load on the linear motor. The output of the linear motor is effectively used as the driving force of the shaft feeder.

According to a sixth aspect of the present invention, there is provided an electric discharge machining apparatus driven by a linear motor, comprising a numerical controller for performing a relative movement operation between an electrode and a workpiece by a linear motor. In the apparatus, air provided so as to directly apply a pulling force to a moving object including a quill configured as a mover of a linear motor provided to be movable in a vertical direction with respect to a processing table on which the processing object is mounted. A cylinder, a supply pressure setting means for setting a pressure supplied to the air cylinder, and the discharge in response to at least one of a power-on signal, an electrode replacement signal, an NC program operation start signal, or a machining start signal of the electric discharge machine. A storage device in which a control program for setting a supply pressure of an air cylinder in accordance with an operation state of the processing device is stored; An electric discharge machining apparatus of the linear motor drive, characterized in that it comprises a processing unit (CPU) for outputting a signal relating to the supply pressure setting to the supply pressure setting means.

According to the linear motor driven electric discharge machining apparatus of the present invention, the quill of the machining head is constituted as a movable element of the linear motor, and the air cylinder is provided substantially on the center axis of the driving thrust of the linear motor acting on the quill. Thus, the pulling force of the air cylinder is directly applied substantially coaxially with the axis.
With this configuration, the followability is secured, the couple is not applied to the shaft feed mechanism due to the thrust of the air cylinder, the linearity of the shaft feed is maintained, and no vibration occurs during the high-speed jump operation. Then, a program for changing and controlling the thrust to be started in response to at least one of a power supply signal of the electric discharge machine, an electrode replacement signal, an NC program operation start signal or a machining start signal is calculated. The processing device executes and determines a set value of a supply pressure to the air cylinder according to an operation state of the electric discharge machining device. The set value is output to the supply pressure setting means for supplying the air cylinder so that the supply pressure becomes the determined supply pressure. The supply pressure setting means supplies air at the set pressure to the air cylinder to reduce the load on the linear motor, and the output of the linear motor is effectively used as the driving force of the shaft feeder. Sex can be maintained.

According to a seventh aspect of the present invention, there is provided an electric discharge machining apparatus driven by a linear motor according to the present invention, comprising a numerical controller for performing a relative movement operation of an electrode and a workpiece by a linear motor. In the apparatus, air attached so as to directly apply a pulling force to a moving object including a quill configured as a mover of a linear motor provided to be movable in a vertical direction with respect to a processing table on which the processing object is mounted. A cylinder, a supply pressure setting means for setting a pressure to be supplied to the air cylinder, a storage device storing a reference value of a current command corresponding to a pressure set value suitable for an operation state of the electric discharge machining device, A current command value from the linear motor drive control device in response to at least one of a device power-on signal, an electrode replacement signal, an NC program operation start signal, or a machining start signal. A storage device storing a control program for setting the supply pressure of the air cylinder so that the current command value becomes the reference value, and executing the control program and outputting a required pressure setting signal to the supply pressure setting means. An electric discharge machine driven by a linear motor, comprising an arithmetic processing unit (CPU).

According to the linear motor drive electric discharge machine of the present invention, the quill of the machining head is constituted as a movable element of the linear motor, and the air cylinder is provided substantially on the center axis of the driving thrust of the linear motor acting on the quill. Thus, the pulling force of the air cylinder is directly applied substantially coaxially with the axis.
Then, in response to at least one of a power-on signal of the electric discharge machine, an electrode replacement signal, an NC program operation start signal or a machining start signal, the pressure supplied to the air cylinder is adjusted to a pressure suitable for the operation state of the electric discharge machine. The reference value is called from a storage device storing a reference value of the current command corresponding to the set value, and the current command value is read from the linear motor drive control device so that the air command value becomes the reference value. The arithmetic processing unit executes a program for setting the supply pressure of the cylinder, and determines a set value of the supply pressure to the air cylinder according to the operation state of the electric discharge machine. The set value is output to the supply pressure setting means for supplying the air cylinder so that the supply pressure becomes the determined supply pressure. The supply pressure setting means supplies air at a set pressure to the air cylinder, and the air cylinder directly applies a required auxiliary thrust to the quill without causing a couple to act on the shaft feed mechanism.

According to another aspect of the present invention, there is provided an electric discharge machining apparatus driven by a linear motor, comprising a numerical controller for performing a relative movement operation between an electrode and a workpiece by a linear motor. In the processing device, the auxiliary thrust is directly applied to a moving object including a quill configured as a mover of a linear motor provided to be movable in a vertical direction with respect to a processing table on which the processing object is mounted. An air cylinder, supply pressure setting means for setting a pressure to be supplied to the air cylinder, and a position deviation value at the time of movement of the moving object from the linear motor drive control device in response to a processing start signal, the position deviation being monitored. A storage device storing a control program for changing and controlling the supply pressure of the air cylinder when the value exceeds a predetermined value; and An electric discharge machining apparatus of the linear motor drive, characterized in that it comprises a processing unit (CPU) for outputting a required pressure setting signal to the setting means.

According to the linear motor driven electric discharge machining apparatus of the present invention, the quill of the machining head is constituted as a movable element of the linear motor, and the air cylinder is provided substantially on the center axis of the driving thrust of the linear motor acting on the quill. Thus, the pulling force of the air cylinder is directly applied substantially coaxially with the axis.
At the time of electric discharge machining, the position deviation value of the moving object during movement is read from the linear motor drive control device, and the read position deviation value is compared with a predetermined position deviation value. The arithmetic processing unit executes a program for increasing the supply pressure to the cylinder, and outputs a setting signal for increasing the supply pressure to the air cylinder to the supply pressure setting means. As the supply pressure increases, the pulling force generated by the air cylinder increases, and an auxiliary thrust against the negative pressure acting on the moving object is given. This supplementary thrust compensates for the lack of thrust of the linear motor without the couple acting on the shaft feed mechanism,
The output of the linear motor is effectively used as the driving force of the shaft feeder, and the quill is quickly jumped.

According to a ninth aspect of the present invention, there is provided an electric discharge machining apparatus driven by a linear motor, comprising a numerical controller for performing a relative movement operation of an electrode and a workpiece by a linear motor. In the apparatus, air attached so that an auxiliary thrust acts directly on a moving object including a quill configured as a mover of a linear motor provided to be movable in a vertical direction with respect to a processing table on which the processing object is mounted. A cylinder, input means for inputting data relating to a machining mode determined by a machining shape, a machining electrode shape, a machining electrode weight, etc. or an operation state of the electric discharge machine, and a supply pressure setting means for setting a pressure supplied to the air cylinder A storage device storing a set value for setting a supply pressure of an air cylinder corresponding to the input value; and a processing mode from the storage device. Others are discharge machining system for a linear motor drive, characterized in that it comprises a processing unit (CPU) for executing a control program to be outputted to the supply pressure setting means retrieves the required set value corresponding to the operating state.

According to the linear motor driven electric discharge machining apparatus of the present invention, the quill of the machining head is constituted as a movable element of the linear motor, and the air cylinder is provided substantially on the center axis of the driving thrust of the linear motor acting on the quill. Thus, the lifting force of the air cylinder is directly applied substantially coaxially with the axis. Then, when data relating to the machining mode determined by the machining shape, machining electrode shape, machining electrode weight, etc. or the operating state of the electric discharge machining device is input from the input means, the arithmetic processing unit reads air corresponding to the input value from the storage device. A set value for setting the supply pressure of the cylinder is called, and the set value is output to the supply pressure setting means. The supply pressure setting means supplies air at a set pressure to the air cylinder, and the air cylinder directly applies a required auxiliary thrust to the quill without causing a couple to act on the shaft feed mechanism.

According to a tenth aspect of the present invention, there is provided a linear motor driven electric discharge machining apparatus for achieving the above object.
10. The electric discharge machine according to claim 6, further comprising an electropneumatic regulator provided in supply pressure setting means for setting a pressure supplied to the air cylinder. It is.

According to the electric discharge machining apparatus driven by the linear motor according to the present invention, the supply pressure setting means for setting the pressure supplied to the air cylinder is an electropneumatic regulator, and the numerical control device outputs the voltage value as a precise value. Thrust can be given to the quill.

According to the eleventh aspect of the present invention, there is provided a linear motor driven electric discharge machining apparatus for achieving the above object.
10. The electric discharge machine according to claim 6, wherein the supply pressure setting means for setting the pressure supplied to the air cylinder comprises a high relief air regulator and a solenoid valve. It is a driven electric discharge machine.

According to the electric discharge machining apparatus driven by a linear motor of the present invention, the supply pressure setting means for setting the pressure supplied to the air cylinder is constituted by the high relief air regulator and the solenoid valve, and the supply pressure set value is set by the solenoid valve. The switching signal is used to switch to the high relief air regulator in which the desired supply pressure is set, so that a required auxiliary thrust can be directly applied to the quill even when the load of the linear motor suddenly changes.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing the overall configuration of a mechanical portion of a die-sinking electric discharge machine according to the present invention in which a linear motor is mounted as a drive source of a Z-axis feeder. In FIG. 1, 1 is a bed, 2 is a column standing upright on the rear side or upper surface of the bed 1, and 3 is a saddle provided on the bed 1 on the front of the column 2 so as to be movable in one horizontal (Y-axis) direction. Reference numeral 4 denotes a ram provided on the saddle 3 so as to be movable in the other horizontal one axis (X-axis) direction. Reference numeral 5 denotes a processing tank provided on the front side of the column 2 of the ram 4.
A work table (not shown) is provided, and a work table is provided to face the work electrode E in a state of being immersed in a work fluid.

Reference numeral 7 denotes a processing head attached to the column front surface 2A extending toward the processing tank 5 on the upper part of the column 2, and is a hollow columnar body as a whole, and has a substantially square shape having a mounting means 8A for the processing electrode E at the lower end. It includes a quill 81 made of a lightweight material such as a columnar ceramic. And quill 8
Reference numeral 1 denotes a linear guide device (not shown) provided between the rear surface of the quill 81 and the front surface of the column 2 or the inner surface of the processing head 7 so as to be freely linearly movable in the vertical direction. 10
Are provided on both side surfaces of the processing head 7 so as to face, via a minute gap, permanent magnets (not shown) arranged in a predetermined number in the moving direction on the opposing side surfaces of the quill 81 at right angles to the vertical direction. A pair of electromagnet devices including a yoke and a winding excitation coil, that is, an excitation stator of a so-called linear motor, which moves a quill 81 on which a permanent magnet is attached as a movable element. 61 is a quill 8 described later.
1 is an air cylinder that is attached to 1 and constitutes a part of a thrust assist device that generates a thrust in an upward direction in the figure.

FIG. 2 is a cutaway view showing the structure of a substantially central portion of the processing head 7 shown in FIG. In FIG. 2, a base member 7A is attached to a front surface 2A of the column 2, and stators 10 are attached to inner surfaces of two side walls perpendicular to the column 2 of the base member 7A. The upper and lower portions of the base member 7A have openings, and a quill 81 that constitutes the mover 8 that can move in the vertical (Z-axis) direction through the openings is provided. This quill 81
The electrode attaching means 8A is attached to the lower side.

The stator 10 includes a coil yoke, and coils formed by winding a wire with a predetermined number of turns on the coil yoke are arranged at predetermined intervals. On the other hand, the mover 8 includes a quill 81 and a magnet plate 42 fixed to the quill 81 at a position facing the coil yoke. On the magnet plate 42, a plurality of permanent magnets 43 are arranged at predetermined intervals. Then, a predetermined current adjusted to match a desired command value from a motor drive control device (not shown), which will be described later, flows through the coil and is excited to generate a predetermined magnetic force with the permanent magnet 43 of the magnet plate 42. Then, the quill 81 moves in the vertical direction by the magnetic force. The position of the quill 81 is detected by the quill 81 and a position detecting device LS attached to the base member 7A, and the position information is sent to the motor drive control device and the quill 81 is moved to a position instructed by the numerical control device.
Is controlled. As described above, the quill 81 in which the magnet plate 42 on which the plurality of permanent magnets 43 are fixed is mounted on the pair of side surfaces is provided with the electrode mounting means 8A, and the moving object of the Z-axis feeder is constituted as a whole.

On the front surface 2A of the column 2, two linear motion ball bearing guides 52 for guiding the moving object in the Z-axis direction are provided. Two bearing blocks 52A are provided so as to be engaged with the side surfaces of the quill 81 facing the quill 81, respectively. The quill 81 is slidably guided in the vertical direction by the engagement between the linear motion ball bearing guide 52 and the bearing block 52A provided on the quill 81.

An air cylinder 61 constituting a part of the thrust assist device is suspended from above the base member 7A together with the quill 81. By supplying and exhausting the air pressure in the air cylinder cylinder 61a while maintaining a desired air pressure by a supply pressure setting device described later, the air pressure is adjusted and a predetermined thrust is given to the quill 81. The air cylinder 61 mainly includes a cylinder cylinder 61a, a piston 61b reciprocally housed in the cylinder cylinder 61a, a seal member 61c between the piston and the cylinder inner wall, and a piston rod 61d connected to the piston.

In this embodiment, the flange of the air cylinder 61 is mounted on the upper end of the quill 81 with several bolts.
Firmly fixed. The connection member 47 is provided on the upper part of the quill 81, and the piston rod 61d is suspended or held. In the configuration shown in FIG.
1, the upper cylinder cylinder 61a with the piston 61b in between.
The quill 81 fixed to the air cylinder 61 is supported by a desired thrust by supplying air at a desired pressure from the supply port 61e. When the quill 81 largely moves in the vertical direction, the upper air in the cylinder 61a is supplied or exhausted in accordance with the change in the position, and the upper air pressure in the cylinder 61a is reduced to the desired pressure. Is to be maintained.

With the above construction, the quill 81 has high responsiveness as the mover 8 of the linear motor, the thrust of the air cylinder 61 acts directly on the quill 81 and the center of the linear motor thrust. A machining head capable of assisting thrust in a form suitable for an electric discharge machine having excellent followability and good straightness of axial movement by substantially matching the position. By using the air cylinder 61 as an auxiliary thrust source, the pressure of the air in the air cylinder 61 is set such that the quill 81 does not move due to the weight of the moving body portion including the electrode of the processing head during the preparation work. In other words, irrespective of the position of the quill 81, the quill 81 does not fall downward and may damage the mechanical device without generating a magnetic force for holding the position between the stator 10 and the mover 8. Absent. Since this thrust is always maintained during movement, the quill 81
When the workpiece is moved, the weight of the moving object of the processing head 7 is not added as a load. Therefore, the stator 1
The magnetic force between the zero and the mover 8 need only be approximately the thrust for moving the inertial mass of the mover 8.
Since no thrust is required to counteract gravity, the linear motor can be reduced in size and the processing head does not increase in weight. In addition, since the counterweight is directly applied to the mover 8 instead of connecting the counterweight with a wire rope as in the conventional balance device, it has good followability and can generate vibration even when performing a high-speed jump operation. There is no.

Further, in the configuration of the present invention, since the thrust of the air cylinder is provided so as to act substantially at the center of the mover 8, there is no fear of bending moment and the linearity of the shaft feeder can be maintained. Further, as will be described later, the operating state of the electric discharge machine and the form of machining, that is, a machining electrode shape, a weight or a machining shape, or a pressure value set according to machining with a minute electrode or machining with a large machining area are set. If it does, the performance of the linear motor obtained by directly driving the quill 81 will not be impaired.

Next, the overall configuration of the electric discharge machine including the thrust assist device of the present invention will be described with reference to FIGS.

FIGS. 3 and 4 are block diagrams showing the overall structure of the present invention including a thrust assist device. The supply pressure setting device using an electropneumatic regulator for setting the pressure of the air cylinder 61 is provided. The first embodiment of the present invention, and the second embodiment having a supply pressure setting device using a supply pressure switching circuit for performing a plurality of pressure settings in order to set pressure instead of the electropneumatic regulator 64. Is shown. In addition,
In the configuration described in the embodiment of FIG. 2, the air cylinder 61 is fixed to the quill 81 at the upper end of the quill 81, and the quill 81
3 and 4, the air cylinder 61 is directly fixed to the stationary portion (column 2) of the machine main body, and the piston A configuration in which the rod 61d is connected to the quill 81 via the connecting member 47 is shown. Depending on whether the air cylinder 61 is the moving side or the fixed side, the supply port 61e to which the air is supplied is upside down, but in any case, the air is supplied to the cylinder chamber on the supply port 61e side. There is no change.

In FIG. 3, the thrust assisting device includes an air dryer 62a for drying air from an air source supplied to an air cylinder 61, and a filter 62 for removing dust.
b, Oil mist filter 6 for removing oil mist
2c and an air regulator 63 for stabilizing the supply pressure, and an electropneumatic regulator 64 and an electropneumatic regulator for setting the air pressure to be supplied as a part of the supply pressure setting device for controlling the air pressure of the thrust assist device. A D / A converter 65 that converts a command value of the numerical controller 100 into an analog signal and outputs the same to the numerical controller 64, and a numerical controller 10 that controls a set voltage of the electropneumatic regulator 64.
0 of the thrust control program stored in the storage device 102. Like the conventional control device, the numerical control device 100 includes a CPU 101 and a storage device 102 such as a hard disk in which a control program required for NC program operation such as an NC program decoding processing function and a display function of the numerical control device is stored. , RAM for temporary storage memory
103, an input device 104 for inputting an NC program and various settings necessary for the program operation, a display device 10 for displaying a machine operation status, an input screen for performing various settings, and the like
5. I / O unit 10 for inputting / outputting to / from motor drive control device 110 and hardware part for performing thrust assist control of the present invention
6. The numerical control device 100 has an I / O 10
6, a position command is output to the motor drive control device 110, the necessary position information and the current command value of the exciting coil of the stator 10 of the linear motor are output from the motor drive control device 110,
Receives position deviation values during axis feed.

The conventional apparatus always uses the counterweight for the purpose of balancing so that the balance force is equal to the weight of the moving object, whereas the apparatus of the present invention uses the operation of the machine. An attempt is made to enable the setting of the thrust assist according to the state (during preparation operation or NC program operation including electric discharge machining), according to a change in the weight of the machining electrode or machining electrode, or according to the machining shape or machining type. Things. Therefore, in the preparatory work before machining, the current flowing through the exciting coil of the linear motor is reduced to save energy and suppress heat generation, assuming that the weight is balanced or slightly higher than the balance force. In order to achieve this object, it is desirable to adjust the auxiliary thrust as needed when turning on the power of the apparatus, replacing electrodes, processing, or operating the NC program. Further, more preferably, when a large negative pressure acts during a jump operation of the electrode when the machining area is large during electric discharge machining, the thrust assist is set high to reduce the load on the linear motor, and the pressure in the air chamber is increased. Is set larger by one or more steps. Also, in the case of processing that requires a high-speed jump with a long distance, the air supply to the air cylinder 61 due to the jump operation is increased by similarly setting a relatively high value to compensate for the pressure fluctuation in the air chamber.

Next, the operation of the apparatus of the present invention configured as described above will be described with reference to FIGS. 5, 6, 7, 8 and 9.

FIG. 5 shows the thrust assisting control operation performed by the apparatus of the present invention after the power of the numerical controller 100 is turned on (hereinafter referred to as “source power ON”). This shows the entire flow of the control operation performed from the time when the power is turned on (hereinafter, referred to as power ON) to the time when the power is turned off (hereinafter, referred to as power OFF) in the other parts. Numerical control device 1
When the source power of 00 is turned on, the CPU 101 initializes each setting and makes the power ON possible (S101).
1). Then, in S2, the CPU 1 operates until the power is turned on.
01 continues the standby state, and when the power is turned on, processing S3 for setting the air pressure when the power is turned on is executed.

Here, the process of S3 will be described with reference to FIG.

In FIG. 6, the thrust assist control execution flag is set to "1" in S51, the thrust assist control program is called from the storage device 102, and the processing is started by the CUP 101. In the process at the time of power ON, the quill 81,
The weight of the moving object of the processing head 7 including the electrode mounting means 8A is balanced by the thrust of the thrust assist device, and the current value flowing to the excitation coil of the stator 10 of the linear motor is reduced from 0 or a value close to it, for example, to the weight. It is desirable to set the value to about 10 kg higher to suppress heat generation due to unnecessary current. Here, the higher pressure is set such that a lifting force in the normal Z-axis direction acts on the moving object in consideration of a case where the electrode E is manually attached by the operator or a power failure during the preparation work. It is to keep. Hereinafter, a case where the reference value is 0 will be described in the present embodiment. In S52, the motor drive control device 1
In order to set the current command value from 10 to the coil of the electromagnet apparatus to 0, the current reference value is set to 0 using the current command value as a thrust assist reference value to be compared. Note that a current value flowing through the coil may be detected using a detector instead of the current command value. Next, the current command value of the motor drive control device 110 is brought into a state where it can be taken in via the I / O 106 (S5).
3). When the power is turned off, the lock device for preventing the moving body from dropping is released (S54), and the thrust assist control is performed (S55).

Here, the thrust assist control process will be described with reference to FIG. The processing of the thrust assist control program in FIG. 9 is performed in the linear motor drive controller 110 which is proportional to the current reference value as the thrust assist reference value stored in the storage device 102 and the output of the linear motor controlled by the motor drive controller 110. The output value to the electropneumatic regulator 64 is changed while performing the feedback control until the thrusts coincide with each other.
This is a process for setting the air pressure to be supplied to 1.

When the thrust assist control program starts, first, n = 1 is set as the first process (S8).
1), the thrust assist reference value S set in S51 of FIG. 6 is taken (S82), and the current command value DA inside the motor drive control device 110 is taken (S83). In S84, the first deviation Δe1 between the reference value S and the current command value DA is obtained, and the process proceeds to S85. The determination in S85 is Yes, that is, the deviation Δ
If e1 is 0, it is assumed that the value already matches the reference value.
The setting is returned to n = 0, the control is terminated (S90), and the process proceeds to S56 in FIG. If the determination in S85 is NO, the process proceeds to S86, in which a value obtained by adding the current deviation Δen and the previous deviation Δen-1 (0 in the first processing), that is, an integrated value Δein of the deviation value is obtained ( S86). Next, in S87,
Δein multiplied by integral gain Ki and current deviation Δe
The value obtained by multiplying n by the proportional gain Kp is calculated by the integral control process and the proportional control process, and these are added by the adder to obtain the control amount Cn (S88). The calculated control amount Cn
Is sent to the D / A conversion unit 65 via the I / O 106,
The voltage value is converted to a voltage value by the / A conversion unit 65, and the voltage value is output to the electropneumatic regulator 64 (S88). Then, 1 is added to n, and the process returns to S83 to perform the second process. In the second process, S83 and S84 are executed again, and S85
To make a second determination. If they do not match, the above processing is repeated until the deviation Δen becomes zero. This S8
When the processing from S3 to S89 is repeated, the deviation gradually decreases, and finally the processing ends in a state where the value obtained by multiplying Δein by the integral gain is held as the output value. Where K
The values of i and Kp are set to appropriate values that do not cause a delay in the control system and do not cause a vibration phenomenon. Thus, the pressure in the air cylinder 61 supplied and exhausted by the electropneumatic regulator 64 is
To the pressure specified by the thrust auxiliary reference value,
The pressure converges to substantially balance the weight of the moving object. Therefore, if the thrust assist reference value is set slightly larger, the pressure in the air cylinder 61 converges to a pressure larger than the pressure substantially balanced with the weight of the moving object.

Returning to FIG. 6, when the thrust assist control process is completed, the process proceeds to S56, where the taking of the current command value is stopped, the thrust assist control execution flag is set to 0, and the process of S3 in FIG. It is in a state of waiting for a driving command by the operator. of course,
At this time, a comment indicating that the thrust assist control has ended may be displayed.

Returning to FIG. 5, when the processing of S3 is completed, S4
It is determined whether the electrode replacement command has been issued by the operator. Here, when the operator replaces the electrode with another electrode set in the electrode replacing device, the thrust assist control is executed based on the electrode replacement input of the operator. In S4, when an electrode replacement is instructed by the operator, the automatic electrode replacement device provided in the electric discharge machine is operated to replace the electrode, and after the electrode replacement is completed, the process proceeds to S4a. In S4a, the CP
U101 calls and executes the electrode replacement process shown in FIG. 7 stored in the storage device 102.

FIG. 7 is a flow chart showing the thrust assist control when the electrode is replaced. This process is executed when an electrode replacement command is input by an operator or when there is an electrode replacement command in the NC program, and is executed particularly when the electrode weight changes greatly. If the electrode weight does not change much, there is no need to execute control.
The change in the electrode weight can be known from the change in the current command value. Therefore, the numerical controller can also obtain the electrode weight.

In FIG. 7, when an operator issues an electrode replacement command (operation on the electrode automatic replacement device) or an electrode replacement command during the operation of the NC program, the electrode replacement is performed.
After the electrode replacement operation, the thrust assist control execution flag is set to 1 and the thrust assist program is executed (S60). next,
In S61, it is determined whether or not an auxiliary thrust has been set in advance by the operator, and if it has been set, the process proceeds to S611.

In step S611, a screen for requesting the operator to input information such as a machining mode, for example, a machining projection area, an electrode weight, a deep hole machining, a micro machining, or a directly input thrust assist reference value or a set pressure value. The information input by the input device 104 is called from the storage device 102. As the input screen, for example, items related to the above-described processing modes are displayed in a list together with selection numbers, and an input screen for selecting one of the numbers or a screen for directly inputting the electrode weight and the set pressure value can be used. In S612, based on the called selection number or input value, CP
U101 performs a process of converting to a voltage value to the electropneumatic regulator. Then, the converted voltage value is sent to the D / A conversion section 65 via the I / O 106, and the set voltage is output from the D / A conversion section 65 to the electropneumatic regulator. And the process returns to S5 in FIG.

The thrust assist reference value stored in the storage device 102 is determined in advance by experiments or the like to determine the correspondence, or is determined as a theoretical reference value and is determined by the storage device 102.
What is necessary is just to store it.

Returning to S61 in FIG. 7, if no auxiliary thrust has been input, the current command value of the linear motor drive control device 110 can be read (S62).
The current command value DA is read (S63). Then, it is determined whether the next step current command value DA has changed by a predetermined value or more (S64). In the process of FIG. 6 described above, the moving object is already in a state in which the weight of the electrode before replacement is balanced with the electrode before replacement. Therefore, if the weight of the electrode after replacement changes, the current command value also changes. ing. Here, it is desirable to always adjust the auxiliary thrust with respect to the change in weight. However, in this embodiment, in order to perform the process promptly, although it depends on the rated thrust value of the linear motor, for example, a change of about 5 kg or more in weight is required. In this case, an example in which the adjustment of the auxiliary thrust is performed, and if it is less than that, the adjustment is not performed again and the process ends at that time is illustrated.

When the weight change of the electrode is equal to or more than a predetermined value,
If the determination is YES, the current command value is stored (S65).
At this time, the tool numbers may be stored in association with each other, and used when the same electrode is specified later.

At S66, the current command value as the thrust assist reference value is set to zero. In S67, the process shown in FIG. 9 is performed, and the current command value reading state is terminated (S68).
The thrust assist control flag is set to 0, and the process ends (S6).
9). When the series of processing in FIG. 7 ends, the process proceeds to S5 in FIG.

In the case of FIG. 6, the thrust assist control process shown in FIG. 9 was performed using the current command value as the thrust assist reference value. However, in the case of FIG. In addition to the control process, the thrust assist value corresponding to the machining mode is directly output as a voltage value to the electropneumatic regulator 64 without using the current command value. When used in the embodiment of FIG. 4 described later, a solenoid valve selection signal to be opened is output as a thrust assist value.

In S5, the CPU 1 of the numerical controller 100
01 is in a standby state of the apparatus operation by the NC program, and repeats the processing of S4 and S5 until the execution instruction of the NC program is issued. In S5, if there is an NC program execution command, the NC program is decoded and the operation is started. And
Proceeding to S6, it is confirmed whether or not a program code relating to the exchange operation (ATC operation) relating to the electrode exchange is present in the NC program. If there is, the tool exchange operation of S6a is executed, and the process proceeds to the electrode exchange process of S6b. . This S6b
Is the same as the above-described processing of S4a, and therefore the description is omitted.

If there is no electrode replacement command, then in S7,
It is determined by the NC program whether or not to perform electric discharge machining. If the electric discharge machining is not the NC program, the program for one block is executed and the process proceeds to S9. If the NC program is completed, the process proceeds to S10, and if the power is turned off, all the thrust assist control operations are completed. S9
If the NC program does not end, the process returns to S6 to repeat the processing. If the power is not turned off in S10, the process returns to S4 and waits for the processes in S4 and S5 to enter a standby state.

Returning to S7, if it is the execution of electric discharge machining, the judgment is Yes, and the process enters into the electric discharge machining process S7a shown in FIG.

The process of S7a is a control process for increasing the auxiliary thrust to be activated at the time of electric discharge machining. In the jumping operation during normal sinking electric discharge machining, the electrode is moved at the highest possible acceleration when the electrode is retracted, and a sharp machining fluid flow is generated in the machining gap, thereby discharging the machining debris remaining in the machining gap. Is significantly increased. However, if the electrode is retracted in a short time (0.1 to 0.5 seconds), a large negative pressure acts on the electrode when the processing area is large, because a large amount of processing liquid is sucked between the electrodes. When the weight is large, considerable thrust is required due to the inertial mass of the electrode itself. In such a case, it is determined that the position deviation (so-called accumulation pulse) with respect to the position command of the linear motor when the moving object is being fed and moved by the linear motor is large, and it is determined that an overload is applied. The operation stops working. However, in reality, it is not an overload due to a collision between the electrode and the workpiece, but rather because a predetermined movement amount is not performed due to a negative pressure and a position deviation exceeding a predetermined amount has occurred. By taking into account the above, it is possible to avoid an overload state by applying an auxiliary thrust when the electrode is retracted. The process flow shown in FIG. 8 is a control for monitoring the position deviation of the linear motor drive control device 110 and increasing the auxiliary thrust when the position deviation exceeds a predetermined value so that a required high-speed jump operation can be performed.

In FIG. 8, in S70, required electric discharge machining conditions are set, and electric discharge machining is started. Then, at a predetermined cycle, for example, the position deviation value of the linear motor drive control device is fetched in accordance with the jump operation (S71), and S7
In step 2, it is determined whether the deviation value is equal to or greater than a predetermined value. However, the reference deviation value is set to a value lower than the set value at which the protection circuit operates. If the determination result is NO, the process proceeds to S80, and if not completed, the process returns to S71. S
If the determination at 72 is YES, there is a possibility that the negative pressure may further increase as the machining proceeds, so that the thrust assist execution flag is set to 1 and the current command value is read as in the above-described processing (S73, S74). , S75). Here, in S76, since the thrust is insufficient with the value at the time of the thrust assist control, the set value for increasing the predetermined reference value stored in advance in the storage device by one step is called, and the thrust in the backward direction acts on the moving object. As described above, the thrust assist control shown in FIG. 9 is performed (S77). After raising the auxiliary thrust by one step, stop taking in the current command value,
The thrust assist control flag is set to 0 (S79), and the routine proceeds to S80. If the processing is completed, the processing at the time of processing ends and S
Then, the process returns to S72, and the above-described processing is repeated until the processing is completed.

Here, as another embodiment, when the position deviation is equal to or larger than the predetermined value in the judgment of S72, the process proceeds from S73 to S79.
Instead of executing a series of thrust assist control, the storage device 10
2 is stored in advance with an output voltage value for increasing the supply / discharge air pressure of the electropneumatic regulator 64 by one step, and when the position deviation exceeds a predetermined value, the output voltage is increased stepwise according to the magnitude of the position deviation. It is also possible to perform a process of calling a value and outputting the value directly to the electropneumatic regulator 64 via the D / A converter 65. It is also possible to store a voltage value against the negative pressure in advance and switch to the set value for output. In the processing in this case, it is not necessary to gradually increase the auxiliary thrust and repeat the thrust auxiliary control until the position deviation becomes equal to or less than a predetermined value. Further, as another embodiment, the integral gain Ki multiplied by the above-mentioned control amount Cn may be increased by one step only during the upward jump, or a predetermined amount according to the magnitude of the position deviation may be added to the control amount Cn. It is valid. Thus, the air pressure controlled in accordance with the thrust assist reference value is further increased to compensate for the thrust shortage of the linear motor. high speed,
The same thrust assist control can also be employed in machining that requires a large stroke jump.

If the determination in S80 is YES, the process proceeds to S80 in FIG.
Return to 8 and the above processing turns off the power of the EDM
It continues until it is done.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. FIG. 4 shows an embodiment in which a pneumatic pressure switching circuit is provided as a supply pressure setting device instead of the relatively expensive electropneumatic regulator 64, and thrust assist control is performed step by step. In FIG. 4, the same reference numerals as those in FIG. The difference from the embodiment shown in FIG. 3 is that a plurality of air regulators with relief valves (hereinafter referred to as high relief air regulators) 66 a to 66 d provided for adjusting the air pressure and an air supply line to the air cylinder 61 are switched. This is a processing program stored in the storage device 102 in the numerical control device 100 and the plurality of solenoid valves 67a to 67d. In the drawing, the case where four high relief air regulators are used is illustrated. However, if it is desired to set the air pressure more accurately, more high relief air regulators may be provided and the number may be determined as necessary. good. The air dryer 62a is
This circuit need not be used.

The air pressure of each of the high relief air regulators 66a to 66d for supplying air to the air cylinder 61 is set by adjusting the relief valve of the high relief air regulator with an adjustment knob (not shown).

For example, when the weight of the movable element 8 including the electrode mounting means 8A is about 50 kg and the air cylinder having a sectional area of 25 cm ² is used, the set pressure is set to one high relief air regulator 66a. The pressure of the air is 2 kg / cm ² to 2.4 kg / cm ² and is used to balance the weight of the moving object. The other high relief air regulators 66 b and 66 c are sequentially provided with the electrode weight and processing form. In consideration of the above, a high supply pressure is set in a stepwise manner as appropriate. Also, the processing area is 100 ~
An air pressure of 4 to 6 kg / cm ² is also prepared as a setting against the negative pressure acting when working with a 150 cm ² electrode. Since the electrode weight and the size of the electrode used in the electric discharge machining device are substantially determined by the size of the mechanical device, an air cylinder having a larger sectional area may be adopted for a large mechanical device. As described above, the high relief air regulator, the supply pressure of which has been adjusted in a plurality of stages, is switched and controlled by the solenoid valves 67a to 67d as necessary, and the required thrust assist is performed.

When the thrust assist is not performed, all the solenoid valves are closed, the relief valve (not shown) is opened, and the air in the air cylinder 61 is exhausted.

Next, the operation of the embodiment of FIG. 4 will be described. When the power is turned on, in the case of the present embodiment, the control flow shown in FIG. 6 is connected to the high relief air regulator in which pressure is set to balance the weight of the mover 8 among the high relief air regulators described above. The process can be completed only by opening the solenoid valve and supplying air pressure to the air cylinder. In contrast to the operation at the time of electrode replacement of FIG. 7, in the case of this embodiment, when the operator specifies and inputs the auxiliary thrust, the solenoid valve connected to the high relief air regulator that supplies the specified pressure is opened. If there is no designation by the operator, steps S61 to S63 shown in FIG. 7 are executed first, and it is determined whether or not the current command value DA has exceeded a predetermined value due to electrode replacement. If the value is equal to or greater than the predetermined value, the solenoid valve of the high relief air regulator whose pressure setting is set to be higher by one step is opened instead of the thrust assist control of S65 and S67 (the currently opened electromagnetic valve). The valve is closed), and the processes of S62 and S63 are executed again.
If it is determined that the current value is equal to or more than the predetermined value, the process is repeated until the current command value becomes equal to or less than the predetermined value to perform appropriate pressure setting.

Next, the processing operation during processing will be described.
In this case, S70, S71, S72 of the processing flow of FIG.
Is executed similarly. In S71, the position deviation value accompanying the movement of the moving object is monitored at predetermined time intervals, for example, in accordance with the cycle of the jump operation. If the position deviation value is equal to or more than the predetermined value in the determination of S72, the process proceeds to S7.
In place of the processing of steps S4 to S78, the solenoid valve of the high relief air regulator whose pressure setting is set higher by one step is opened (the currently opened solenoid valve is closed), and the processing of S71 and S72 is executed again. I do. If the next determination is also equal to or greater than the predetermined value, this process is repeated until the positional deviation value becomes equal to or less than the predetermined value. The solenoid valve of the high relief air regulator set at an appropriate pressure against the negative pressure acting on the electrode is opened. To If a high-relief air regulator that takes into account the negative pressure is provided, it may be switched directly.In that case, the thrust against the expected negative pressure is calculated in advance, and the high-relief air regulator is calculated. Set the pressure.

As described above, in the embodiment of FIG. 4, a plurality of high relief air regulators having different pressure settings are prepared, and the current command value and the position deviation value of the motor drive control device 110 are read by the numerical control device 100. The control is performed by switching the solenoid valve so that the supply pressure to the air cylinder becomes an appropriate pressure value, and thrust assist can be performed relatively inexpensively.
Further, in the embodiment of FIG. 4, when the current command value or the position deviation value is equal to or more than a predetermined value, a warning or a message is displayed on the display device 105, and the operator adjusts the relief valve of the high relief air regulator. It is also possible to configure so that the air pressure setting can be changed. In this case, the CPU calculates the required pressure value from the current command value and the deviation value, and displays a preferable set pressure value together with a message on a display device. In this case, the required pressure value can be easily set.

As described above, according to the present invention, the configuration is such that the thrust can be appropriately assisted depending on the operation state of the Die-sinker EDM apparatus. In the case where the same type of processing is continuously performed without changing the processing mode, the supply pressure set once is stored in the storage device, and after the power is turned on, the set value is set. The supply pressure can be set by calling.

[0077]

According to the method of the present invention, as described above, the quill of the processing head is constituted as a movable element of the linear motor, and the air cylinder is provided substantially on the center axis of the driving thrust of the linear motor acting on the quill. Thus, the lifting force of the air cylinder is directly applied substantially coaxially with the axis to prevent the couple from acting on the shaft feed mechanism. Then, the air pressure supplied to the air cylinder is set to an appropriate air pressure according to the operation state of the electric discharge machining device, and the pulling force generated by the air cylinder is constantly applied to the quill to reduce the load on the linear motor, and to reduce the output of the linear motor. Is effectively used as the driving force of the shaft feeder, so that advantages can be obtained without impairing the performance of the linear motor.

Further, at the time of electric discharge machining, while preventing a couple from acting on the shaft feed mechanism, the supply pressure to the air cylinder is increased to increase the pulling force generated by the air cylinder.
This compensates for the lack of thrust of the linear motor because it opposes the negative pressure acting on the moving body, and the output of the linear motor is effectively used as the driving force of the shaft feeder, and the quill high-speed jump operation is performed without hindrance. .

According to the apparatus of the present invention, as described above, the quill of the processing head is constituted as a movable element of a linear motor,
An air cylinder is provided substantially on the center axis of the drive thrust of the linear motor acting on the quill, and the pulling force of the air cylinder is configured to be directly applied substantially coaxially with the axis. Due to the thrust force, no couple acts on the shaft feed mechanism, the linearity of the shaft feed is maintained, and no vibration occurs during the high-speed jump operation. In addition, since the pressure set value suitable for the operation state of the electric discharge machine can be set, the load on the linear motor is reduced, and the output of the linear motor is effectively used as the driving force of the shaft feeder, and the linear motor can be made compact. High responsiveness can be maintained.

Further, at the time of electric discharge machining, the arithmetic processing unit executes a program for increasing the supply pressure to the air cylinder when the positional deviation value is equal to or more than a predetermined value, and the supply pressure to the air cylinder is increased to generate the air cylinder. As the pulling force increases, an auxiliary thrust against the negative pressure acting on the moving object is given without the couple acting on the shaft feed mechanism, which compensates for the lack of thrust of the linear motor, and the output of the linear motor is effectively fed. The quill can be used as a driving force of the device and the quill can quickly perform a high-speed jump operation.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an overall configuration of a mechanical part of a die-sinking electric discharge machine according to the present invention.

FIG. 2 is a cutaway view showing a structure of a substantially central portion of the processing head 7 shown in FIG. 1;

FIG. 3 is a diagram of a first embodiment provided with a supply pressure setting device using an electropneumatic regulator;

FIG. 4 is a diagram of a second embodiment using a supply pressure switching circuit for setting a plurality of pressures.

FIG. 5 is a diagram showing an overall flow of a thrust assist control operation performed by the device of the present invention.

FIG. 6 is a diagram showing a flow of a process of setting an air pressure when power is turned on.

FIG. 7 is a diagram showing a flow of a process for setting air pressure at the time of electrode replacement.

FIG. 8 is a diagram showing a flow of a control process for increasing air pressure during electric discharge machining.

FIG. 9 is a diagram showing a flow of a thrust assist control process.

[Explanation of symbols]

2 Column 7 Processing head 7A Base member 8 Mover 8A Electrode mounting means 10 Stator 42 Magnet plate 43 Permanent magnet 52 Linear motion ball bearing guide 52A Bearing block Linear motion ball bearing guide 61 Air cylinder 67a, 67b, 67c, 67d Solenoid valve 81 Quill 100 Numerical controller LS Position detector

Claims (11)

[Claims] In a method for assisting axial feed thrust of an electric discharge machine equipped with a numerical controller for performing a relative movement operation between an electrode and a workpiece by a linear motor, a workpiece to be configured as a movable element of a linear motor is machined. It is provided movably in the vertical direction with respect to the table, and is arranged so that the air cylinder thrust acts directly on the substantially central axis of the axial driving thrust acting on the moving object. When replacing,
In at least one stage of an operation state such as an NC program operation or an electric discharge machining, linear air is supplied to the air cylinder to supply a required pressure to the moving object to apply a required auxiliary thrust according to the operation state. Thrust assist method for motor driven electric discharge machine. 2. An axial feed thrust assisting method for an electric discharge machine equipped with a numerical controller for performing a relative movement operation of an electrode and a workpiece by a linear motor in a vertical direction with respect to a machining table on which the workpiece is mounted. The thrust of the air cylinder is arranged so that the thrust of the air cylinder acts directly on the substantially central axis of the axial driving thrust acting on the moving body constituted as a movable element of a linear motor movably provided, and the power supply of the electric discharge machine is turned on. In at least one stage of the operating state, such as when replacing an electrode, when performing an NC program operation, or when performing electrical discharge machining, the current command value of the linear motor driving device is read and the current command value is stored in a previously stored current reference value. A pressure setting signal is output to the supply pressure setting device of the air cylinder so that the pressures substantially coincide with each other, and air at a required pressure is supplied to the air cylinder, and the air is supplied to the moving object in accordance with an operation state. A thrust assisting method for a linear motor driven electric discharge machine for applying a required assisting thrust. 3. An axial feed thrust assisting method for an electric discharge machine equipped with a numerical controller for performing a relative movement operation between an electrode and a workpiece by a linear motor, in a vertical direction with respect to a machining table on which the workpiece is mounted. A power supply for the electric discharge machining apparatus, wherein the thrust of the air cylinder is arranged to directly act on the substantially central axis of the axial driving thrust acting on the moving body constituted as a movable element of a movably provided linear motor, Closing signal,
Calling a required reference thrust value from a storage device in response to at least one of an electrode replacement signal, an NC program operation start signal, or a machining start signal; and reading a current command value from a linear motor drive control device; Performing a step of obtaining a deviation between the reference thrust value and the current command value, and a step of outputting a pressure setting signal to the supply pressure setting means in accordance with the deviation value until the reference thrust value and the current command value match, An integral value of the deviation value obtained by repeating the calling step, the reading step, and the step of obtaining the deviation is output to the supply pressure setting means, the cylinder pressure of the air cylinder is set, and a required auxiliary thrust is applied to the moving body. Thrust assist method for linear motor driven electric discharge machine. 4. A method for assisting axial feed thrust of an electric discharge machine equipped with a numerical controller for performing a relative movement operation between an electrode and a workpiece by a linear motor in a vertical direction with respect to a machining table on which the workpiece is mounted. It is arranged so that the thrust of the air cylinder acts directly on the substantially central axis of the axial drive thrust acting on the moving body constituted as a movable element of a movably provided linear motor, at the time of NC program operation or electric discharge machining Reading from the linear motor drive control device a position deviation value at the time of movement of the moving object; comparing the read position deviation value with a predetermined position deviation value; Outputting a signal for increasing the supply pressure to the air cylinder to the pressure supply pressure setting means at the time of changing the cylinder pressure of the air cylinder, and A thrust assisting method for a linear motor driven electric discharge machine, comprising a step of applying force. 5. An electric discharge machine equipped with a numerical controller for performing a relative movement operation of an electrode and a workpiece by a linear motor while directly suspending a machining head to which a machining electrode is attached by using an air cylinder so as to be axially fed. A step of setting and inputting a required auxiliary thrust according to a machining mode or an operation state of the electric discharge machine, and a step of calling an auxiliary thrust value stored in a storage device corresponding to the input value. Outputting a pressure setting signal to the supply pressure setting means based on the called auxiliary thrust value; and changing the supply pressure so that the supply pressure of the air cylinder substantially matches the thrust value. Supplying the changed air pressure to the air cylinder to generate a required auxiliary thrust, thereby applying the required auxiliary thrust to the moving body of the shaft feeder. Thrust assist method for linear motor driven electric discharge machine. 6. An electric discharge machine equipped with a numerical controller for performing a relative movement operation between an electrode and a workpiece by a linear motor, wherein the electrical discharge machining apparatus is provided movably in a vertical direction with respect to a machining table on which the workpiece is mounted. An air cylinder provided to directly apply a pulling force to a moving object including a quill configured as a mover of a linear motor, supply pressure setting means for setting a pressure to be supplied to the air cylinder, and an electric discharge machine. A storage device storing a control program for setting a supply pressure of an air cylinder according to an operation state of the electric discharge machine in response to at least one of a power-on signal, an electrode replacement signal, an NC program operation start signal, and a machining start signal. And an arithmetic processing unit (CPU) for executing the control program and outputting a signal relating to the supply pressure setting to the supply pressure setting means. An electric discharge machine driven by a linear motor. 7. An electric discharge machine equipped with a numerical controller for performing a relative movement operation between an electrode and a workpiece by a linear motor, wherein the electrical discharge machining apparatus is provided movably in a vertical direction with respect to a machining table on which the workpiece is mounted. An air cylinder mounted so that a pulling force acts directly on a moving object including a quill configured as a mover of a linear motor, supply pressure setting means for setting a pressure to be supplied to the air cylinder, and an electric discharge machine. A storage device storing a reference value of a current command corresponding to a pressure set value suitable for an operation state, and at least one of a power-on signal, an electrode replacement signal, an NC program operation start signal, or a machining start signal of the electric discharge machine The control program reads a current command value from the linear motor drive control device in response to the control signal and sets the supply pressure of the air cylinder so that the current command value becomes the reference value. A storage device in which the program is stored;
An electric processing device (CPU) for executing the control program and outputting a required pressure setting signal to the supply pressure setting means. 8. An electric discharge machine equipped with a numerical controller for performing a relative movement operation between an electrode and a workpiece by a linear motor, wherein the electrical discharge machining apparatus is provided so as to be vertically movable with respect to a machining table on which the workpiece is placed. An air cylinder mounted so that an auxiliary thrust acts directly on a moving object including a quill configured as a mover of a linear motor, supply pressure setting means for setting a pressure supplied to the air cylinder, and a processing start signal. In response, the linear motor drive control device monitors a position deviation value of the moving object during movement and stores a control program for changing and controlling the supply pressure of the air cylinder when the position deviation value exceeds a predetermined value. And a processing unit (CPU) for executing the control program and outputting a required pressure setting signal to the supply pressure setting means. EDM machine driven by a linear motor. 9. An electric discharge machining apparatus provided with a numerical controller for performing a relative movement operation between an electrode and a workpiece by a linear motor, the apparatus being provided movably in a vertical direction with respect to a machining table on which the workpiece is placed. An air cylinder mounted so that auxiliary thrust acts directly on a moving object including a quill configured as a mover of a linear motor, and a machining form or electric discharge machining determined by the machining shape, machining electrode shape, machining electrode weight, etc. Input means for inputting data relating to the operation state of the device, supply pressure setting means for setting a pressure supplied to the air cylinder, and a set value for setting a supply pressure of the air cylinder corresponding to the input value are stored. A control device for extracting a required set value corresponding to a processing mode or an operation state from the storage device and outputting the set value to the supply pressure setting means. An electric discharge machining apparatus driven by a linear motor, comprising an arithmetic processing unit (CPU) for executing a program. 10. The electric discharge machine according to claim 6, wherein the supply pressure setting means for setting the pressure supplied to the air cylinder is an electropneumatic regulator. Electric discharge machine. 11. The electric discharge machine according to claim 6, wherein the supply pressure setting means for setting the pressure supplied to the air cylinder comprises a high relief air regulator and a solenoid valve. EDM machine driven by a linear motor.