JPH10263933A - Wire electrical discharge machining method and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a worker with little experience to apply machining excellent in shape accuracy by preparing parameters prior to machining, calculating a correction path, and moving the center of a wire on the correction path of a corner section. SOLUTION: The position apart from the point F by the distance registered on a data storage device and an offset quantity on a path FG is set as a correction completion point K (step S140), and the coordinates of the correction completion point K and the inclination of the path FG on the XY coordinate system are substituted in the outlet side correction equation g(X, Y) registered on the data storage device to establish the g(X, Y) (step S150). The intersection of the inlet side correction equation f(X, Y) and outlet side correction equation g(X, Y)is obtained (step S160), and when the intersection exists, a stored path S50 is substituted for the correction path (step S170).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire electric discharge machining method and a wire electric discharge machine for machining a work by relatively moving a wire and a work by NC control.

[0002]

2. Description of the Related Art The wire electric discharge machining method is a method in which a voltage is applied between a wire and a work which are opposed to each other with a gap therebetween, and the work is machined by generated discharge energy. Such a wire electric discharge machining method will be described with reference to FIG. FIG. 5 is a system diagram of a conventional wire electric discharge machine. In the figure, 1
Is the workpiece to be processed. 2 is a work mounting table. 3 is a table to which the mounting base 2 is fixed. 4X and 4Y are motors for moving the table 3 in the X-axis and Y-axis directions, respectively. 5
Is a wire and a reel 6a with a predetermined tension applied.
And wound up on the reel 6b. 7a, 7b
Is a guide for positioning the wire 5. Reference numeral 8 denotes a processing power supply for supplying electric power between the work 1 and the wire 5. 9
Is an NC device, which includes a computing unit 9a, a storage unit 9b, and a control unit 9c, and performs various controls for automatically performing machining. Reference numeral 10 denotes a keyboard for inputting commands and numerical values necessary for the NC device 9.

Next, the processing procedure of the above-mentioned conventional wire electric discharge machine will be described. FIG. 6 is a front view of the work 1.
Reference numeral 11 denotes a product, which is a square whose vertices are indicated by solid lines A, B, C, and D. In the case of finishing the product 11 by two processes, usually, first, emphasis is placed on the machining speed rather than the quality of the machined surface, and under machining conditions in which the discharge energy is large, a square abcd indicated by a dotted line slightly larger than the product size is formed from the work 1. Cut out (hereinafter called first cut). Next, emphasizing the quality of the machined surface rather than the machining speed, and under the machining conditions where the discharge energy is small, the square ABCD indicated by the solid line indicating the square abcd
(Hereinafter referred to as second cut).

In both the first cut and the second cut, additional information and a shape program necessary for the processing are input to the NC unit 9 before the processing. The additional information items include the processing condition determined by the diameter and material of the wire 5, the material and plate thickness of the work 1, and the surface roughness of the processing surface, the diameter of the wire 5, and which side of the traveling direction the wire 5 is offset. And so on. If the storage unit 9b is provided with a database for selecting processing conditions, when the diameter and material of the wire 5, the material and thickness of the work, and the surface roughness of the processed surface are input to the NC device 9, If an appropriate processing condition is selected by the calculation unit 9a and the database is not stored in the storage unit 9b, the operator refers to the processing condition data book and inputs the processing condition to the NC device 9. In each of the above cases, a unique processing condition number is assigned to each processing condition and the processing conditions are arranged. When the processing conditions are determined, the power supply method, the size of the processing gap, the magnitude of the tension to be applied to the wire 5, and the like are determined. In the case of the first cut in FIG. 6, the contents of the shape program include vertices a, b, c, and d, a machining start point S, and an intersection t of a perpendicular drawn from the machining start point S to the line segment da and the line segment da.
And the coordinates of the processing end point and the processing order.

At the time of the first cut, the NC device 9 sets the offset k to the sum of the radius of the wire 5 and the size of the machining gap determined by the machining conditions from the accompanying information, analyzes the shape program, and determines the distance from the square abcd to the offset. Path SR-RL-LM-MN, shown in phantom in the figure, which is quantity k
-NP-PR is calculated, and the table 3 is moved in the X-axis and Y-axis directions so that the center of the wire 5 moves on the above-mentioned path at a constant speed, thereby processing the square abcd. At the time of the second cut, similarly to the above-described first cut, a path (not shown) for moving the center of the wire 5 is calculated from the supplementary information and the shape program to finish the square ABCD.

[0006]

By the way, at the time of machining, the wire 5 bends in a bow shape between the guides 7a and 7b due to the discharge reaction force, and the wire 5 at the part facing the work 1 is bent.
It deviates from the straight line connecting a and 7b. In the case of the first cut, the discharge reaction force is applied almost uniformly to the front semicircular portion in the traveling direction of the wire 5, and its magnitude hardly changes. As a result, the magnitude of the deflection of the wire 5 hardly changes, and almost desired processing can be performed.

[0007] However, in the case of the second cut, as shown in FIG. 7, the length of the oblique line between the wire 5 and the product 11 on the side toward the vertex A, that is, the processing amount is gradually reduced. The discharge reaction force f indicated by the arrow gradually decreases, and the discharge reaction force gradually increases on the side away from the vertex A. Since the tension of the wire 5 is constant, the amount of deflection of the wire 5 gradually decreases on the side toward the vertex A, and gradually increases on the side away from the vertex A. As a result, the center of the wire 5 (actually, the guide 7
Even if a and 7b) are moved, the machined surface is as shown by the solid line in FIG.

Therefore, in the prior art 1, the processing conditions (for example, processing speed, wire tension, processing fluid pressure, etc.) in the corner portion are changed without changing the path obtained by the calculation. Also, the prior art 2 does not change the processing conditions,
The shape accuracy was improved by changing the path at the corner with a shape program.

[0009] However, in any of the above-mentioned prior arts, it is necessary to perform actual machining with another work to collect data. Usually, it is not possible to find an appropriate processing condition or path in one test processing, so that the working efficiency is reduced. Furthermore, in order to select appropriate processing conditions or routes in a short time, experienced workers were required.

[0010] An object of the present invention is to solve the above-mentioned problems in the prior art and improve the working efficiency.
Another object of the present invention is to provide a wire electric discharge machining method and a wire electric discharge machine which enable even an inexperienced operator to perform machining with excellent shape accuracy.

[0011]

In order to achieve the above object, a first aspect of the present invention is to calculate a path at a distance of an offset amount with respect to a finished shape, and to move a wire center along the path. In the machining method, the path correction formula and parameters of the corner part are prepared for each machining condition,
Prior to machining, a correction path is calculated using the path correction formula and the parameter, and the corner moves the center of the wire along the correction path instead of the path.

According to a second aspect of the present invention, there is provided a wire electric discharge machine for calculating a path at a distance of an offset amount with respect to a finished shape, and moving a center of a wire along the path. A data storage unit having a correction formula and parameters; and a control unit for calculating a correction route based on the route correction formula and the parameters, and the corner unit moving the center of the wire along the correction route instead of the route. It is characterized by.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a system diagram of a wire electric discharge machine according to an embodiment of the present invention, in which the same reference numerals as those in FIG. Reference numeral 21 denotes a data storage device, as shown in FIG. 2, a corner angle θ to be applied for each processing condition, and a path correction formula f (X, Y) on the entrance side.
And the path correction equation g (X, Y) on the exit side, and the parameters of the entrance distance p, exit distance q, entrance angle α and exit angle β are registered. The signs of the entrance angle α and the exit angle β are reversed depending on the direction of the offset.

Next, the operation of the present embodiment will be described with reference to FIGS. 3 and 4 for a case where a second cut is performed according to the processing condition number 1001 in FIG. FIG. 3 is a flowchart showing a control procedure, and FIG. 4 is a plan view of a corner portion.
The vertex A in FIG. 6 is enlarged. Prior to the processing, the supplementary information and the shape program are input to the NC device 9 (procedure S10 shown in FIG. 3), and then the correction of the corner path is input to the NC device 9 (procedure S20).
When the route calculation start button is turned on (step S30),
The NC device 9 has a path SE-E centered on the wire 5 as in the prior art.
F-FG ... are calculated (step S40), and the result is stored (step S50). The steps up to step S50 are the same as those in the related art.

Next, it is confirmed whether or not the corner section needs to correct the path (step S60). If it is, the process of step S70 is performed, and if not, the process ends (step S200). In step S70, the presence or absence of a corner portion of the route is searched from the machining start point S to the end point.
The process of 0 is performed, and when there is no corner portion, the process ends (step S200). In step S80, the processing start point S
From the to the processing end point (i is 1, 2, 3 ...)
Is calculated at the intersection of the path (i) and the (i + 1) -th path at the connection point, and it is determined whether 30 ≦ θ (step S90). If 30 ≦ θ, the process of step S100 is performed, and if θ <30, an alarm is displayed and the operation ends (step S110). In step S100, it is determined whether or not θ ≦ 170. If θ ≦ 170, the process in step S120 is performed. If 170 <θ, the process in step 70 is performed without performing correction in the corner. In the case of FIG. 4, first, in step S80, it is calculated that the angle between the first path SE and the second path EF is θ _E = 270 degrees, and the procedure returns to step 70 via steps S90 and S100. That is, the path is not corrected at the connection point E between the path SE and the path EF.

Next, a second route EF and a third route F
The angle θ _F at the connection point F of G is calculated, and since θ _F = 90 degrees, the process of step S120 is performed. That is, on the route EF, a position separated from the point F by the distance p and the offset amount k registered in the data storage device 21 is set as the correction start point I, and the coordinates _XI , YI of the correction start point _I and the XY coordinate system are used. The inclination γ of the path EF is substituted into the entrance-side correction formula f (X, Y) registered in the data storage device 21 to determine f (X, Y) (step S130). Further, the distance q and the offset amount k registered in the data storage device 21 from the point F on the route FG.
Is set as the correction end point K (step S140),
The coordinates X _K , Y _{K of the} correction end point K and the slope δ of the path FG in the XY coordinate system are substituted into the exit-side correction formula g (X, Y) registered in the data storage device 21 to obtain g (X, Y). Is determined (step S150). Next, the intersection Q of the entrance side correction equation f (X, Y) and the exit side correction equation g (X, Y) is obtained (step S16).
0), when the intersection Q exists, the path EF-FG stored in step S50 is replaced with the correction path EI-IQ-QK-KG (step S170), and the process of step S70 is performed. If the intersection Q does not exist, that is, if the entrance-side correction formula f (X, Y) and the exit-side correction formula g (X, Y) are parallel, the process of step S110 is performed. Hereinafter, similarly, the correction path of the corner portion is calculated, and the path stored in step S50 is replaced with the correction path.

At the time of machining, the NC device 9 moves the table 3 in the X-axis and Y-axis directions so that the center of the wire moves along the stored path. Excellent processing can be performed.

In the above embodiment, before the machining, the path through which the wire 5 passes is calculated in advance. For example, even if the angle θ of the corner portion is less than 30 degrees or there is no intersection Q, the machining is not interrupted. In addition, it is possible to perform processing with excellent shape accuracy.

In the above description, all the routes are straight lines. However, when one of the routes is a straight line and the other is a curve, the angle at which the tangent of the curve at the connection point intersects the straight line is determined. Just do it. Further, the function formula for calculating the correction paths on the entrance side and the exit side is not limited to the linear expression, and may be an n-order expression or another functional expression, and the angle θ is 30 ≦ 30.
The range is not limited to θ ≦ 170, and may be further expanded. If θ <30 in step S90, the process of step S70 may be performed instead of displaying an alarm (step S110). Similarly, step S160
In the case where there is no intersection in step, an alarm is displayed (step S11).
Instead of 0), the process of step S70 may be performed. Further, the selection of the correction control may be performed on a program, or the data table may be stored in the storage unit 9b of the NC device 9 without providing the data storage device 21. Further, a correction path of a corner portion to be processed may be calculated while processing is being performed.

[0020]

As described above, according to the present invention,
A path correction formula and parameters are prepared for each processing condition, and before processing, a correction path of a corner portion is calculated using the path correction formula and parameters, and is adjusted according to a change in the amount of deflection of the wire due to a change in discharge reaction force. Since the path is corrected, it is not necessary to perform test processing, and the work efficiency can be improved. Further, since it is not necessary to change the processing conditions at the corners or to change the input of the path on a program, even an inexperienced operator can perform processing with excellent shape accuracy.

[Brief description of the drawings]

FIG. 1 is a system diagram of a wire electric discharge machine according to an embodiment of the present invention.

FIG. 2 is a diagram showing data stored in a data storage device.

FIG. 3 is a flowchart showing a control procedure.

FIG. 4 is a plan view of a corner portion.

FIG. 5 is a system diagram of a conventional wire electric discharge machine.

FIG. 6 is a front view of a work.

FIG. 7 is a diagram showing a magnitude of a discharge reaction force at a corner portion and a machining result.

[Explanation of symbols]

 5 wire 21 data storage device

Claims (2)

[Claims] 1. A wire electric discharge machining method for calculating a path at a distance of an offset amount with respect to a finished shape and moving a center of a wire along the path, wherein a path correction formula and parameters for a corner portion are prepared for each machining condition. In addition, prior to machining, a wire compensation machining method is characterized in that a compensation route is calculated based on the route compensation formula and the parameters, and the corner moves the center of the wire along the compensation route instead of the route. 2. A wire electric discharge machine for calculating a path at a distance of an offset amount with respect to a finished shape and moving the center of a wire along the path stores a path correction formula and parameters of a corner portion for each machining condition. And a control section for calculating a correction path based on the path correction formula and the parameters stored in the data storage section, and controlling the corner to move the center of the wire along the correction path instead of the path. And a means for providing a wire electric discharge machine.