JPH0253526A - Wire cut electric discharge machine - Google Patents

Abstract

PURPOSE:To enable a machine to be automatized by combining a workpiece in its quality and thickness with a wire in its quality and diameter, reading a machining data in accordance with a number of finish machining times or final machining surface roughness and setting a condition from the machining data and a wire offset amount. CONSTITUTION:A setting part 10, first by input combination of a workpiece 7 in its quality and thickness with an electrode wire 4 in its quality and diameter, selects a corresponding machining condition table 11 next reads a machining data, corresponding to a number of finish machining times or final finish surface roughness, from the selected machining condition table 11. Using one part of the read machining data, an offset amount of the electrode wire 4 in each finish machining is obtained, and an adequate electric discharge machining condition is set from this offset amount and the machining data and given to a power unit device 3 and an NC device 14. While using a condition correction table 12 by a signal from a fluid pressure sensor 13, an electric discharge machining condition is automatically reset. Thus a wire cut electric discharge machine enables its automatization to be contrived.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wire-cut electric discharge machine, and more particularly, to a wire-cut electric discharge machine that can automatically set appropriate electric discharge machining conditions.

[Conventional technology]

The conditions for wire-cut electrical discharge machining are greatly influenced by the material and thickness of the workpiece and the material and diameter of the wire. Therefore, conventionally, the pulse conditions of the machining power source are set in accordance with each combination of these four conditions.

A table is provided in which various machining data such as wire running speed, wire tension, and machining fluid supply are registered.

Processing conditions were searched and set by inputting the four conditions.

On the other hand, if the amount of machining fluid is the same as that during normal machining at the start of machining, the amount of fluid will be too large and the fluid flow will be disturbed, leading to machining problems such as air intrusion. Insufficient discharge of the wire may result in wire breakage.Therefore, in order to obtain machining data according to these machining conditions, a table is created in which machining data for these machining conditions are registered. In other words, the machining conditions corresponding to the 5 machining conditions are treated as one machining condition that is exactly the same as the normal machining conditions.1 For example, various machining data at the start of machining for one of the combinations of the four conditions are It was registered as one processing condition.

[Problem to be solved by the invention]

According to the prior art described above, processing data that can be set according to one of the combinations of the four conditions is a standard one.
It was only the processed data.

Therefore, operators can perform high-speed machining and low hydraulic precision machining.

It is necessary to correct the machining data that has been set depending on the type of machining such as primary, secondary, etc. finishing machining.

You can also specify the number of finishing operations or the roughness of the final finished surface.
Finishing process (skim cut) that goes through several steps,
It was impossible to automatically set processing conditions. That is,
When using skim cutting to reduce machining data and repeat machining to improve dimensional accuracy and finish the machined surface, it is necessary for the operator to obtain and register the machining data for each cutting step in advance. Met.

Furthermore, the machining conditions depending on the machining state vary depending on the type of machining in addition to the combination of the four conditions described above.
Conventionally, this was not possible due to the huge number of processing conditions.

As described above, in the past, it was necessary for the operator to frequently intervene in setting the machining conditions, which caused problems in that setting the machining conditions was troublesome and that it was not always possible to set the machining conditions to appropriate conditions.

An object of the present invention is to provide a wire-cut electric discharge machine that can automatically set appropriate electric discharge machining conditions.

[Means to solve the problem]

In order to achieve the above object, in the present invention, a wire functioning as an electrode is passed through a workpiece.

The wire is held on both sides of the workpiece, and the workpiece is electrically discharge-machined by electric discharge between the workpiece and the wire while supplying machining fluid to a portion where the workpiece and the wire face each other. In wire-cut electrical discharge machines, at least.

a plurality of machining condition tables provided corresponding to the combinations of the material and thickness of the workpiece and the material and diameter of the wire, each of which stores machining data corresponding to a plurality of machining types; and the electric discharge machining. and a setting section for setting conditions for.

The setting section selects the settings according to the input of the combination of the material and thickness of the workpiece, the material and diameter of the wire, the number of finishing operations, or the roughness of the final finished surface.

Read machining data from the machining condition table, determine the offset amount of the wire in each finishing machining based on the machining data, and use the read machining data and the offset amount to determine conditions for electric discharge machining in each finishing machining. The purpose is to set the .

[Effect]

According to the above means, the setting section sets the electrical discharge machining conditions as follows.

First, a processing condition table corresponding to a combination of four input conditions (hereinafter referred to as main classification conditions) of the material and thickness of the workpiece and the material and diameter of the wire is selected.

Next, the input number of finishing operations or final finished surface roughness (
or machining type).

Read from the selected processing condition table. At this time, the final finished surface roughness is converted into the number of finishing operations, and then the processing data is read out.

Then, using part of the read machining data, the amount of wire offset in each finishing machining is determined. Appropriate electrical discharge machining conditions are automatically set from this offset amount and machining data.

〔Example〕

FIG. 1 shows an embodiment of the invention.

In FIG. 1, 1 is a wire cant electrical discharge machine.

2 is a machining fluid supply nozzle, and 3 is a power source for electrical discharge machining.

4 is a wire, 5 is a wire traveling device, 6 is a machining fluid supply device, 7 is a workpiece = 8 is an XY child table 9 is a conductor, 1
0 is a setting section, and 101 is a condition search calculation section.

102 is a condition correction processing section, 11 is a processing condition table, 12 is a condition correction table, 13 is a hydraulic pressure sensor, 14 is an NC device, and 15 is a servo circuit.

(a) Outline of configuration The wire 4 serves as one electrode of the discharge.

It is made to penetrate through the workpiece 7 which serves as the other electrode. The wire 4 is held on both sides of the workpiece 7 and is caused to travel in the direction of the arrow by a wire traveling device 5. The wire traveling device 5 includes a wire feeding device, a wire winding device, etc. 1
Give the wire a predetermined running speed and a predetermined tensile strength.

In the part where the wire 4 and the workpiece 7 meet.

There are two machining fluid supply nozzles (hereinafter referred to as
A machining fluid having a predetermined hydraulic pressure and a predetermined conductivity is supplied from a machining fluid supply device 6 through a nozzle (referred to as a nozzle) 2.

Between the traveling wire 4 and the workpiece 7, a single electron 9 is connected from the power source 3 with a predetermined pulse width, a predetermined pause time,
A pulse with a predetermined supply voltage and a predetermined peak current is applied. As a result, an electric discharge is generated between the first workpiece 7 and the wire 4, and the workpiece 7 is subjected to electric discharge machining.

The NC device 14 drives the XY child table on which the workpiece 7 is placed in the X direction and the Y direction, thereby moving the wire 4 and the workpiece 7 relative to each other at a predetermined speed. Servo circuit 15
detects the voltage between the wire 4 and the workpiece 7, compares it with a reference voltage (servo voltage), and adjusts the gap between the wire 4 and the workpiece 7 so that the voltage is suitable for machining. A signal for maintenance is sent to the NC device 14.

The setting unit 10 receives main classification conditions as its input.

Given the machining type, status, and hydraulic pressure, the power source 3. NC device 14. Controls the machining fluid supply device 6 and the wire traveling device 5. That is, the electrical discharge machining conditions are automatically set.

A plurality of processing condition tables 11 are provided corresponding to each combination of main classification conditions. One machining condition table 11 stores machining data corresponding to each of a plurality of machining types. This processed data is obtained in advance through experiments and the like.

Condition correction table! A plurality of number 2s are provided corresponding to each special processing state. One condition correction table 12 stores correction values for correcting each piece of machining data in the machining condition table 11 according to each of a plurality of machining types. This correction value is 1
For example, it is expressed as a percentage (%).

In order to use the condition correction table 12, an address indicating the condition correction table 12 corresponding to each machining state is stored in the machining condition table 11.

The hydraulic pressure sensor 13 detects the injection pressure (hydraulic pressure) of the machining fluid in both or one of the upper and lower nozzles 2, and feeds this to the setting section 10.

(b) Input for automatic setting Next, each input to the setting section 10 will be explained.

The input "main classification condition" specifies the material and thickness of the workpiece 7 and the material and diameter (thickness) of the wire 4 to select one of various combinations of main classification conditions.

The input "processing type" can be considered as a secondary bone type condition for the main classification condition, and specifies one of a plurality of processing types. Here, an example of processing type will be shown.

High-speed machining: Machining that places particular emphasis on speed and allows for wire breakage Standard machining: Speeds up to the extent that the wire does not break and precision machining that does not emphasize accuracy = machining between single nozzles that achieves a certain degree of accuracy in one cut (1st cut): Both nozzle open machining where either the upper or lower nozzle must be at least 1 mm away from the workpiece surface; both upper and lower nozzles must be separated from the workpiece surface
1st cant that must be separated by 1 or more: Rough cutting based on the premise of precision and finishing of the machined surface with skim cutting 2nd to 5th cuts: Each of the 2nd to 5th finishing operations after the above rough cutting 1st force 7 to 5th From rough machining to finish machining of a cut, and even in the same rough machining, the purpose of machining, such as whether to emphasize speed or accuracy, and the state in which machining fluid pressure can be applied (size of workpiece, workpiece edge, etc.) The machining conditions differ depending on the distance from the machined hole to the machining position).

Note that the designation of the number of finishing processes corresponds to designating either an ISt cut (first finishing process) or a 5th cut (fifth finishing process). Further, when specifying the final finished surface roughness, conversely, one of the 1st cut and the sth cut is specified based on the specified surface roughness.

Therefore, the final finished surface roughness is included in the processing type.

The input "state" is 2. One of the four states of special machining that is contrasted with the normal machining state: start of machining, servo bank corner machining, and taper machining, as needed (special machining state). Specify when entering the machining state).

The input "hydraulic pressure" is a detection signal of the hydraulic pressure that is sequentially input from the hydraulic pressure sensor 13 that monitors changes in the hydraulic pressure during the 5 machining operations.

Enter the main classification conditions and machining type before starting electrical discharge machining.
Performed by the operator. In addition, the input "state" and "hydraulic pressure" are respectively input to the NC device 14 (or servo circuit 15) during electrical discharge machining.
and obtained from the hydraulic pressure sensor 13.

(C) Machining condition table and condition correction table Next, regarding machining condition table 11 and condition correction table 12, the second
This will be explained using figures.

The processing condition table 11 is provided for each combination of main classification conditions, and the combination of main classification conditions is used as the title (table name) of the processing condition table 11.

This is used when searching. In the horizontal direction of the machining condition table 11, each of the aforementioned machining types is shown, and in the vertical direction, various machining conditions are shown. Therefore, by specifying a combination of main classification conditions and a machining type, machining data for various machining conditions can be obtained.

What are the processing conditions here?

(i) Electrical or mechanical processing conditions: pulse width, pulse rest time, supply voltage 1 peak current,
Servo system, servo voltage, wire running speed, wire tension, machining fluid pressure.

as well as.

(ii) Conditions (data) regarding machining performance (or machining standards) obtained by combining the various conditions described above: machining surface roughness, machining expansion allowance, skim cut depth, machining voltage, machining current, machining fluid pressure, machining fluid conductivity Every time.

The processed data for each of these.

Processing conditions are shown in Table 11.

By providing processing data regarding the items shown in (ii) above, it becomes possible to calculate the amount of wire offset,
Additionally, it is possible to automatically set the finishing process by specifying the (final finishing) surface roughness.

Further, in the vertical direction of the processing condition table 11, the above-mentioned four states are shown. Then, by specifying the type of machining and the state of machining, the page height of the nine-condition correction table 12 can be obtained.

10 to 20 condition correction tables 12 are displayed for each state, and a page name is attached to each condition, which is used at the time of search. The horizontal direction of the condition correction table 12 is the same as the horizontal direction of the machining condition table 11, and the vertical direction is the same as the item shown in (1) above in the vertical direction of the machining condition table 11. Therefore, by specifying the page number and processing type, correction multipliers for various processing conditions can be obtained. Correction multiplier is 1 as a percentage
It is set as 0 to 900 (%) and is multiplied by this in order to correct the corresponding processing data.

Here, an outline of the correction in each state will be shown.

Machining start condition correction: During the set distance after starting machining.

Reduce processing conditions.

Corner machining condition correction: Correct the conditions set according to the size of the angle at a part of the corner of the machining shape.

Taper machining condition correction: During taper machining, the conditions set according to the taper angle are corrected. Servo back condition correction: The wire and workpiece are short-circuited, the machining trajectory is reversed, and the short circuit is recovered and the machining path is returned to the position where it started to reverse. Reduce machining conditions until recovery.

It is as follows.

This correction is performed only during the condition correction distance X shown for each processing type in the condition correction table 12, and after passing this distance Mx, the processing conditions are returned to the original (state without correction).

By providing processed data as described above.

(i) A huge amount of data can be easily managed. Processing data can be easily read out using ``combination of main classification conditions'' + ``processing type.''

This can be done even more easily by encoding these.

Further, the two-condition correction table 12 stores correction multipliers (%) rather than processing data itself.

The number of tables can be significantly reduced.

(ii) Processed data is systematically organized.

Easy to change and add.

Note that the processing condition table 11 and the condition correction table 12 are as follows.

Actually, it is stored in the storage device within the setting unit 10.

(d) Automatic setting of processing conditions Next, automatic setting of processing conditions when final finished surface roughness is designated as the processing type will be explained using FIG.

■ Main classification conditions and final finished surface roughness are input. Then, the condition search calculation section 101 of the setting section 10 performs the following processing.

■ Search processing condition table 11 using the main classification conditions.

Select one.

■ Search the machined surface roughness column of the selected machining condition table 11 and select one machining type that has machining data that satisfies the input "final finished surface roughness."

If the selected processing type is primary finishing processing (n is usually about 5, but can be 10 or more if necessary), the number of skim cuts is set to n (read the number of skim cuts).

■ Determine the wire offset amount O3 for each finishing process using the following formula.

O3,=WD/2+OC,l+ΣCD However, osi: Wire offset amount WD for primary processing:
Wire diameter QC, ,: processing expansion allowance ΣCD for primary finishing machining: total sum of skim cut depths from (i+1) to primary finishing machining Here, each term in this equation can be easily explained using Fig. 4. explain.

41 and 42 are loci of the center of the wire 4 during the (i-1)th and primary processing, respectively, and 71 is the final machined surface to be obtained by the final finishing process. In addition, OC, and OC are the gaps between the wire 4 and the machined surface of the workpiece 7 (i.e., machining expansion allowance) generated during the (i-1) and primary machining, respectively, and OS ;-+ and O3+ are each (i-
1) Wire offset l, CD, during the next and first machining
(i-1) When moving from the next machining to the first machining, the wire 4
This is the distance at which the object 7 is brought closer to the workpiece 7 (i.e., the depth of cut).

The wire offset amount O8 corresponds to the distance between the Ik final processing surface 71 and the center locus of the wire 4, and indicates the position of the wire 4 from the final processing surface 71 at each processing time. wire orasen)! ? tOS is the remaining distance after removing the machining expansion allowance OCゎ and the radius WD/2 of the wire 4 during Wk final (in this case, n-th) finishing machining from the distance between the final machining surface 71 and the machining start surface. is determined to be assigned to n skim cuts.

In the above equation, the wire diameter WD can be known from the main classification condition, and the machining enlargement allowance OC and the sum ΣCD of the skim cut depths can be known from the machining condition table 11.

■ Create one machining condition for each finishing process from 1st to nth. That is, for each finishing process, machining data is read from the machining condition table 11 and associated with the 5-wire offset IQs.

As a result, a skim cut processing process to obtain the input final finished surface roughness is automatically created. That is, it complied with the main classification condition. Number of processing (how many finishing steps to perform)
The machining data and wire offset amount for the stent for each finishing process are automatically set.

In addition, if the number of finishing machining (how many rounds of finishing machining is to be performed) is input as the input "machining type", after performing the process ■ in Figure 3, omitting the process ■, the following process will be performed. be exposed.

In addition, if 1, for example, high-speed machining, standard machining, precision machining, 1-nozzle open machining, 5-nozzle open machining is entered as the machining type, after performing the process ■ shown in Figure 3, processes ■ and ■ will be omitted. Processing (2) is performed and the corresponding machining process is automatically created.

Among the automatically set processing conditions, the pulse width, pulse rest time, supply voltage and peak flow are sent to the power supply 3, the servo method and servo voltage are sent to the servo circuit 15, and the wire running speed and wire tension are sent to the wire running device 5. , machining fluid pressure and machining? (!The electrical conductivity is sent to the machining fluid supply device 6, and the wire offset amount is sent to the NC device 14, respectively, and used to control them.

(e) Processing for correcting machining conditions Next, the case of correcting the automatically set machining conditions according to the machining state will be described with reference to FIGS. 5 to 8.

This correction process is performed by: receiving information regarding the machining state from the NC device 14 (or servo circuit 15);

This is performed by the condition correction processing section 102 of the setting section 10.

■ When machining is started, it is checked once whether or not machining has started.

(2) If it is in the machining start state, a machining start condition correction process is performed, and after the process is completed, process (2) is performed again.

■ If it is not in the machining start state, it is checked whether or not it is in the servo back state.

(2) If it is in the servo bank state, servo bank machining condition correction processing is performed, and after the completion of the processing, processing (2) and subsequent steps are performed.

■ If the servo bank state is not present, it is checked whether or not corner machining is being performed. For this purpose, as shown in FIG. 6, it is determined whether the direction change angle θ when moving from the end point of the line segment currently being executed to the next line segment on the machining path is 150 degrees or less. When θ is 150 degrees or more, it does not affect the discharge of machining fluid, so there is no need to correct the conditions even when machining corners.

■ If the corner angle 0 is smaller than 150 degrees, corner machining condition correction processing is performed, and after the completion of the processing,
Process ■Do the following.

(2) If the corner angle θ is 150 degrees or more, it is checked whether or not it is tapered.

(2) In the case of taper machining, a 1-taper machining condition correction process is performed, and after the completion of the process, process (2) and subsequent steps are performed.

If taper machining is not being performed, the machining conditions are automatically corrected according to the machining state by repeating the process (1) and the following steps during electrical discharge machining.

Note that a plurality of the four correction processes (processes ①, ②, ①) are not performed at the same time.

FIG. 7 shows details of the machining start condition correction process.

(2) When the correction process is executed, one machining condition table it is selected using the input "main classification condition". This machining condition table 11 is combined with the input “machining type” and the “machining type” determined as a result of examination in the 5-condition correction processing unit
Search by ``state'' to find out the page limit of the 2-condition correction table 12.

(1) Search the one condition correction table 12 of the page hidden by the above-mentioned "processing type J, and first know (read) the two-condition correction distance X.

■ In the same way, find out (read) the correction multiplier for each machining condition of the "machining type". And the correction multiplier is
Multiplying the corresponding machining conditions that have already been set,
Find the correction value.

(2) Among the machining paths (line segments), the path from the start point of the correction process to the range of the condition correction path Mx is divided from the others.

For example, as shown in FIG. 8, from the machining start point SP to the end point E
If processing start condition correction processing is to be performed on the processing path up to P (all given by coordinate values), a path of distance X from the processing start point (that is, the starting point of correction processing) is divided from the others. Due to this.

Among the machining paths given as one line segment 5P-EP in the NC device 14, a machining path with a starting distance of X from SP is divided.

(2) Output the correction value to the electronic FA3, etc., and set each processing condition to the corrected value. As a result, electric discharge machining is performed under the corrected machining conditions.

(2) Find the coordinates of the end point Ps (hereinafter referred to as one division point) of the divided machining path and output it to the NC device 14. This determines the end point of the correction process starting from SP.

■ The NC device 14 performs (relative) X up to the 1st division point Ps.
When the movement of the Y child table is completed, a movement completion signal is generated to notify the condition correction processing section 102 of this.

In response to this, output of the correction value is stopped. As a result, each machining condition is returned to the normal (previously automatically set) machining condition output by the two-condition search calculation unit 101. Therefore, electric discharge machining is performed on the machining path 5P-Ps under the corrected machining conditions.

Electric discharge machining is performed under normal machining conditions for the machining path after the dividing point Ps.

■ End point BP when it was considered as one machining path before division
The coordinates of are output to the NC device 14. As a result, the end point of one normal electrical discharge machining is set to the initial value.

With the above, the correction process is completed.

(fl Hydraulic pressure feed bank) Next, a case will be described in which processing is performed to correct automatically set machining conditions in accordance with changes in machining fluid pressure.

The hydraulic pressure during electrical discharge machining is fed back from the hydraulic pressure sensor 13 to the setting unit IO.

When the hydraulic pressure changes by a predetermined value or more, the 1 setting section 10 performs the following process.

First, select the processing condition table 11 corresponding to the main classification condition,
Search for the machining fluid pressure column. Then, machining data with a value equivalent to the feedback input hydraulic pressure is selected, and other machining data (machining [data] in the column of the same machining type) corresponding to this is read.

This read machining data is output as new machining conditions.

Thereby, even if the hydraulic pressure changes, the wire 4 can be prevented from breaking.

[Effects of the Invention] As described above, according to the present invention, a wire-cut electric discharge machine is provided with at least a machining condition table and a setting section, so that the electric discharge machining conditions can be appropriately and automatically set. Can be set. Furthermore, by providing one-condition correction, a regular table, and a hydraulic pressure sensor, it is possible to automatically reset the electric discharge machining conditions according to the machining state and changes in the hydraulic pressure during machining. Therefore, according to the present invention, automation of a wire-cut electrical discharge machine can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the present invention. FIG. 2 is a diagram showing a processing condition table and a condition correction table. FIG. 3 is a process flow for automatically setting machining conditions. FIG. 4 is an explanatory diagram of the amount of wire offset. FIG. 5 is a processing flow for correcting machining conditions. FIG. 6 is an explanatory diagram of corner machining. FIG. 7 is a process flow for correcting machining conditions. FIG. 8 is an explanatory diagram of dividing the machining path. 1 is a wire cut electric discharge machine, 2 is a machining fluid supply nozzle,
3 is a power supply for electric discharge machining, 4 is a wire, 5 is a wire traveling device, 6 is a machining fluid supply device, 7 is a workpiece, 8 is an XY child table 9 is a power supply, 10 is a setting section 2101 is a condition search a calculation unit; 102 is a condition correction processing unit; 11 is a processing condition table;
12 is a condition correction table 13 is a hydraulic pressure sensor, 14 is an NC device,
15 is a servo circuit.

Claims (1)

[Claims] A wire functioning as an electrode is passed through a workpiece, the wires are held on both sides of the workpiece, and machining fluid is supplied to a portion where the workpiece and the wire face each other. In a wire-cut electric discharge machine that performs electric discharge machining on the workpiece by electric discharge between the workpiece and a wire, at least the combination of the material and thickness of the workpiece and the material and diameter of the wire is supported. a plurality of machining condition tables each storing machining data corresponding to a plurality of machining types; and a setting section for setting conditions for the electric discharge machining, the material and thickness of the workpiece being The setting unit reads machining data from the machining condition table in accordance with the input of the combination of the material and diameter of the wire, the number of finishing machining times, or the final finished surface roughness, and based on this, performs processing in each finishing machining. A wire-cut electrical discharge machine characterized in that an offset amount of the wire is determined, and conditions for electrical discharge machining in each of the finishing operations are set using the read machining data and the offset amount.