JPS60108231A - Electrode feed control system of electric discharge machine - Google Patents

Abstract

PURPOSE:To control the synchronous feed without any special interface by converting the detected output of a gap voltage into a digital value so as to input it into a numerical control device and commanding an electric discharge machine tool to feed at a command feed rate converted into an overide value. CONSTITUTION:While an electrode EP is controlled at a command feed rate, a gap voltage detected by a gap voltage detecting circuit 110 is converted into a digital value by an AD-converter 111. An output Va of the converter 111 is converted into an overide value alpha by a processor 102a, a new command feed rate F is obtained, and a feed rate of a travel command Zc is altered to F in an NC- device 102. As a result, the pulse-distributor 103 and subsequent components are controlled by the above command rate and a motor 105 is also controlled by a new command feed rate to alter the feed rate controlling the electrode EP in response to the gap electric voltage.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an electrode feed control system for electric discharge machining machines such as die-sinking and wire cutting, and particularly relates to electric discharge machining in which the feed speed is changed according to the gap voltage. Regarding the electrode feed control method of the machine.

(Prior art) Electrical discharge machines include a wire-cut electrical discharge machine that performs electrical discharge by moving a wire electrode relative to a workpiece along a command path, and a wire-cut electrical discharge machine that performs electrical discharge by moving a wire electrode relative to a workpiece along a command path. There is a die-sinking electric discharge machine that moves the electrode in the direction of the cutting depth and generates an electric discharge between the electrode and the workpiece to perform a 71u machining process on the workpiece that has the same shape as the electrode.

FIG. 1 is a schematic explanatory diagram of the latter two-legged turtle processing machine. The electrode EP serving as a punch is supported by a spindle SP, and a machining feed is applied in the direction of the arrow by a surfo motor (not shown). A rectangular wave machining voltage is applied from a power source PS in a machining liquid between the workpiece WK and the electrode EP. Therefore, by further feeding the electrode while forming a minute gap between the workpiece WK and the electrode EP, the workpiece WK is machined into the same shape as the electrode EP by the number of sparks. The workpiece WK can be easily enlarged to a desired size by controlling processing pulses, energy, etc., and if necessary, the workpiece WK can be enlarged to any size by eccentrically interlocking the electrode EP. To perform such electrical discharge machining, it is necessary to optimally control the relative speed between the electrode EP and the workpiece. Two conventional methods are known for controlling this electrode (die engraving, wire) feeding. The first method is called command speed feeding.
Obtain the optimum feed rate After retreating like this,
This controls the movement to advance again. This method is
If the electrode is fed at the optimum commanded speed, electrical discharge machining can be performed without causing a short circuit.If the gap between the electrode and the workpiece deteriorates and a short circuit occurs, the electrode will be moved backwards and the electrode will be fed at the old commanded speed. It has the advantage that the feed control technology of numerical control devices conventionally used in machine tools can be used. The second method is so-called synchronous feeding, in which the gap voltage is detected and the feeding speed is changed accordingly. This will be explained using tfJ2 diagram.

When the electrode EP and the workpiece WK come closer than a predetermined distance, the gap detection voltage Vd decreases from the voltage Va in the normal state, and when it becomes equal to or less than the limit voltage vb, the gap detection voltage Vd starts to retreat. Electricity 7 at this time
The moving speed V of the pole EP is proportional to the gap detection voltage Vd. As the electrode EP retreats, the distance between the electrode EP and the workpiece WK widens, the gap detection voltage Vd rises, and when the gap detection voltage Vd returns to the control voltage b, the electrode EP stops retreating.
Start moving forward again. The re-advance speed V of this verse is proportional to the gap detection voltage Vd.

(Problems with the prior art) With the conventional first electrode feeding method, no special interface is required to connect the electrical discharge machine to the multi-M control device, and it is easy to numerically control the electrical discharge press machine. Although it has the advantage of being able to configure an inexpensive system, it is difficult to set the optimal feed speed because it feeds at a constant speed regardless of the size of the gap between the electrode and the workpiece. To change the speed, the override switch is manually operated, the override amount is set, and the feed speed is changed accordingly, but this is done by eye, and the problem is that it is difficult to respond to changes in electrical discharge machining conditions because it is originally a constant speed feed. was there. On the other hand, in the conventional second electrode feeding method, the electrode is fed at a speed that corresponds to the actual gap, so it has the advantage that the optimal speed is commanded moment by moment according to the electrical discharge machining conditions. In order to apply voltage digitally, a two-phase signal is generated when the gap detection voltage or reference voltage is exceeded, and when it is below it.
Since the positive (+) direction pulse and negative (-) direction pulse are read from this two-phase signal and the feed speed is changed according to the amount, a special interface for two phases is required. There were problems in that the device configuration was complicated and expensive.

(Objective of the Invention) An object of the present invention is to provide an electrode feed control method for a discharge pressurizer that allows synchronous feed control to be performed by a numerical control device without using a special interface.

(Summary of the Invention) In the present invention, a gap voltage detection means and an analog-to-digital conversion means for converting this detection output into a digital value are provided in an electric discharge heating system in which a numerical control device commands a feed rate to an electric discharge machine. The gap detection voltage is input to the numerical control device as a digital value, and the numerical control device inputs this manually input gap detection voltage to the overwrite step 1.
6, and the command feed rate changed by the override value is commanded to the electric discharge machine. Therefore, in the present invention, since the gap detection voltage is given by the digital input 16, there is no need for a special interface, and the override value can be set as a parameter within the number 4 + ff controller angle, so fine-grained feeding is possible. becomes.

(Example) Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 3 is a diagram showing one embodiment of the present invention, and although a die-sinking electrical discharge machine is explained as an electrical discharge machine, it can also be applied to a wire-cut electrical discharge machine in the same way.
is a paper tape with number 16 control (NC) command data perforated, positioning information for processing, M, S, T
102 is a numerical control (NC) device that stores NC command data such as function information, and reads NC data from a paper tape 101 using a tape reader (described later), and also decodes the read NC data. ,parable? fM,S,
If it is a T function command (not shown), it is sent to the machine side via the power board, and if it is a movement command Zc (↓ command speed, command sending company), it is output to the subsequent stage Norse distributor. The NC device 102 includes a processor 102a that executes arithmetic processing according to a control program, a program memory 102b that stores a predetermined control program, a data memo 1) 102c that stores data, and an operation panel 102d for operation. Tape reader/puncher 102e and single person output port 1
02f and 102g, a current position counter 102h, a display device 102i, and an address/data bus 102j that connects them.

The program memory l02b is composed of a read-only memory (ROM) or a non-volatile memory, and stores a numerical control program for numerically controlling the machine. A machining control program for controlling table feeding, machining voltage, etc. is stored. On the other hand, the data memory 102c is composed of a non-volatile internal memory, and in addition to storing the NC data (inlet position data, etc.) of the paper tape 101, it also stores the inlet program programmed with parameters and user macros in the area PM.

This area PM stores a conversion table between the gap detection voltage Va and O/<Ride arrival α, and this relationship can be set freely. 103 is a pulse distributor, and based on the movement command Zc, the conversion table is stored. A pulse distribution calculation is executed to generate a distribution pulse Ps with a frequency corresponding to the command speed f. 104 is a known acceleration/deceleration circuit that linearly accelerates the pulse speed of the distribution pulse train Ps when the pulse train is generated, and decelerates the pulse speed linearly at the end of the pulse train to generate the pulse train Pi; 105 is an electric discharge machine EDM; A DC motor that processes and feeds the electrode EP; 106 a pulse distributor that generates one feedback pulse EP every time the DC motor rotates by a predetermined amount; 107;
is an error calculation storage unit, which is composed of, for example, a reversible counter, and which stores input pulses and signals generated from the acceleration/deceleration circuit 104.
The difference Er between the number of Pi and the feedback pulse FP is stored. In addition, this error calculation storage unit is stored as shown in FIG.
It may be configured with an arithmetic circuit 107a that calculates r and an error register 107b that stores Er. That is, if the DC motor 105 is instructed to rotate in the forward direction and is rotated accordingly, the error calculation memory □ section 107 counts up the pulse Pi every time a human power pulse Pi is generated, and also performs feedback. Every time a pulse FP occurs, its content is counted down and the number of manual pulses and fee I.
The difference Er in the number of packed pulses is stored in the error register 107b. 108 is a digital-to-analog (DA) converter that generates an analog voltage proportional to the contents of the error register 107b, and 109 is a speed control circuit. In addition, 108.109
constitute the motor drive circuit. EP is electric discharge machine ED
In this electric discharge machine, the electrode EP, which serves as a punch, is supported by a spindle SP, and the machining feed is changed in the direction of the arrow by a servo motor 105, so that the machining electrode EP, which becomes a punch, is changed in the direction of the arrow. Electricity is supplied between WK and electrode EP from a power source PS.

110 is a gap voltage detection circuit, which connects the electrode EP and the work W
Something that detects the gap voltage Va from the applied voltage between K, 11
Reference numeral 1 denotes an analog or digital (AD) converter, which converts the analog gap voltage Va into a dental value.

Next, the operation of the embodiment shown in FIG. 3 will be explained. At this point, the start button on the operation panel 102d has already been pressed, the NC data is read from the paper tape 101 by the tape reader 102e, and the processor 102a sends commands such as machining voltage from the NC data to the electrical discharge machine E via a powerful electrical panel (not shown).
DM, the Z-axis movement command Zc (Z-axis movement amount ΔZ, feed speed f) is given to the input/output capo) 102g, and the electric discharge machine E
It is assumed that the DM electric discharge machining operation has started. Here, when a movement command Zc is given to the pulse distributor 103 from the input/output port 102g, the pulse distributor 103 executes a pulse distribution calculation based on the movement command Zc and adjusts the feed rate f.
Distribution pulse Ps of the number according to the amount of movement at the frequency according to
Output. The acceleration/deceleration circuit 104 receives this distribution pulse Ps, accelerates/decelerates the pulse speed, and generates a command pulse train P.
i is input to the error calculation storage section 1'07. As a result, the contents of the error register 107b are no longer zero, so a voltage is output from the DA converter 108, the motor 105 is driven by the speed +l, +I control circuit 109, and the electrode EP is moved. When the motor 105 rotates by a predetermined amount, the pulse distributor 1
A feedback pulse FP is generated from 06 and manually input to the error calculation storage section 107, and the difference Er between the number of command pulses Pi and the number of feedback pulses FP is stored in the error register 107b. Thereafter, the motor 105 is servo-controlled so that the error Er becomes zero, and the electrode E
P is processed and fed at a specified speed f and moved to a target position.

In this way, while the electrode EP is being controlled to feed at the commanded speed, the gap voltage is detected by the gap voltage detection circuit 110 from the applied voltage from the power source PS, and the detected gap voltage is digitalized by the AD converter 111. It is converted into a value (for example, 5 bits) and output. The processor 102a periodically sends the output Va of the AD converter l11 to the input/output port 102f.
Read through. Processor l 02a is data memory 1
This output Va is converted into an override value α using the conversion table of the area PM of 02C. For example, this conversion table is configured as shown in the following table.

The processor 102a obtains the override value α from this table, performs the following calculation on the preset command speed f, and obtains a new command speed F.

F= fXα Then, input this new command speed F to input/output port 102g.
give to Generally, in the NC device 102, the movement command Zc is given periodically, so at this time, the feed speed of the movement command Zc is changed to F, which is given.

As a result, the pulse distributor 103 and the following are controlled in the same manner as described above, and therefore the motor 105 is controlled to a new command speed, and the feeding speed of the electrode EP is changed in accordance with the gap voltage.

”-1% if you configure the conversion table as shown in the table above.
The override value up to ~1000% can be set to S, and the speed can be changed from 0 to 10 f for the pre-specified speed 11 (f). When the gap between the poles is poor, minute feed is possible). This specified feed rate f is
It may be specified from the paper tape lot or the operation panel 102d, or may be stored in advance in the program memory 102b. Furthermore, since the conversion table is set in memory, it can be set to any value, and can be set freely depending on the type of electric discharge machine and the object to be machined. Similarly, when the specified command speed is fixed in advance, the command speed F is set as the Saiichi variable F value.
may be stored.

Setting this override value is 1% in 1% increments as described above.
In addition to ~1000%, it may be in 10% increments, and the change range may be 0% to 100%. Furthermore, in order to use it for reverse control, the gap voltage Va should be small (for example, '00001
”, “00010”) as a negative override value (
−α%) may be set.

Although the present invention has been described using one embodiment, various modifications can be made within the scope of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As explained above, according to the present invention, in a discharge application system in which a numerical control device commands a feed rate to an electric discharge machine, a gap voltage detection means and a method for converting the detected output into a digital value are provided. Since the gap detection voltage is configured to be input to the numerical control device as a digital value by providing an analog-to-digital conversion means, it has the effect that it can be input to the numerical control device as a type of data without using a special interface. Therefore, the circuit configuration is simple and can be constructed at low cost. Moreover, in the present invention, the input numerical control device converts this manually input gap detection voltage into an override value, and instructs the electric discharge machine to command the command feed rate changed by the override value. In addition to the effect that synchronous feed control can be realized by processing similar to normal override processing, the override value can be set arbitrarily, and therefore, it has the effect that it can be applied to both approach and minute feed, No special program is required for the approach, and fine feed adjustments can be made. For this reason, the feed control function is enriched, and sophisticated electrical discharge machining is possible, and this can be easily realized at low cost, which greatly contributes to the spread of such NG electrical discharge machines.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of an electrical discharge machine, FIG. 2 is an explanatory diagram of an electrode synchronous feed control method, and FIG. 3 is a block diagram of an embodiment for realizing the method of the present invention. In the figure, EP...electrode, WK...work, 102...
・Numerical control device, 105...Feed motor, 110...
- Gap voltage detection circuit, 111...Analog-digital conversion circuit. Patent applicant Representative of FANUC Co., Ltd. Patent attorney Minoru Tsuji (1 other person)

Claims (1)

[Claims] An electric discharge machining machine that performs electric discharge heating by relatively moving an electrode to which a machining voltage is applied and a workpiece, and a number I+0 control device that commands the feed rate of the relative movement to the electric discharge machine. In the Nidis system, the I between the electrode and the workpiece is
It is equipped with a 1m gap voltage detection means for detecting the 1141 gap voltage of tJI, and an analog-to-digital conversion means for converting the detected gap voltage into a digital value, and the numerical system is An electrode feed control method for a discharge press machine, characterized in that an override value is determined from the gap detection voltage, and a command feed rate changed by the override value is commanded to the discharge press machine.