JPH10118848A - Electric discharge machining method and electric discharge machining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate dead-time in rough machining to shorten the machining time, and prevent the generation of concentrated electric discharge to keep the machining stable. SOLUTION: When a machining program is prepared, the machining conditions such as machining clearance are inputted for every process, and these values are stored in a machining condition storage memory 11. In consideration of the area, the shape, etc., of an electrode 4, an amount of jump-return and its lower limit value of the electrode 4 in the finishing process are inputted, and these values are set in a jump-return amount setting part 12. During the period of electric discharge machining, an execution value calculation part 13 calculates the execution value of the amount of jump-return based on the stored data on the machining conditions and the set data on the amount of jump-return, and a feed mechanism control part 14 controls a feed mechanism 5 for the electrode 4 according to the calculation results. Thus, the electrode 4 jumps with a large amount of return as the process proceeds from rough machining to finishing machining.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge machining method and apparatus for machining a work while jumping an electrode.

[0002]

2. Description of the Related Art In electric discharge machining involving a jump operation, if the amount of jump return of an electrode (distance from a jump start position to a jump end position) is short, machining becomes unstable, for example, a concentrated discharge occurs in finishing machining. Conventionally, the amount of jump return has been set to a fixed value of 20 to 30 μm or more in consideration of safety.

[0003]

However, in rough machining, since the electrode gradually approaches the work by controlling the gap, if the amount of jump return during this period is set large,
Dead time without processing occurs. Therefore, according to the conventional electric discharge machining method, there is a problem that the machining time is longer as the removal amount of the machining portion by the rough machining is larger.

Accordingly, an object of the present invention is to provide an electric discharge machining method and apparatus capable of shortening machining time by eliminating waste time in rough machining, and stably maintaining machining without generating concentrated discharge in finish machining. To provide.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an electric discharge machining method according to the present invention provides an electric discharge machining method for machining a workpiece while jumping an electrode. It is characterized in that the electrode jumps with a larger return amount as the process proceeds from the rough processing to the finishing processing.

In order to carry out the above method, an electric discharge machining apparatus according to the present invention comprises means for storing machining conditions for each process, means for setting the amount of return of an electrode and its lower limit, storage data and setting data. Means for calculating the execution value of the jump return amount based on the calculation result, and means for controlling the feed mechanism of the electrode according to the calculation result. The feature is that the electrode jumps with a larger return amount as the process proceeds from rough processing to finish processing. And In addition, the above method can be carried out without any calculation. In this case, the electric discharge machining apparatus has means for correlating and storing the machining condition and the optimum value of the jump return amount for each process, and the electrode according to the stored data. And a means for controlling the feed mechanism.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the electric discharge machine. A table 2 is provided inside the processing tank 1, and a work 3 is placed on the table 2. Electrode 4
Is driven up and down by the feed mechanism 5 to generate an electric discharge between the work 3 and the work 3 in the working fluid 6, thereby forming a hole 3 a having a shape similar to itself in the work 3. The workpiece 3 is efficiently processed by intermittently jumping the electrode 4 during this processing. Further, ordinary electric discharge machining includes a plurality of steps from rough machining to finish machining, but a required machining surface roughness can be obtained by switching machining conditions for each process.

The electric control system of the electric discharge machine includes a machining condition storage unit 11, a jump return amount setting unit 12, and an execution value calculation unit 1.
3 and a feed mechanism control unit 14 are provided. When creating a machining program, machining conditions such as machining clearance are input for each process, and the values are stored in the machining condition storage unit 11. Also, in consideration of the area and shape of the electrode 4, the amount of jump return of the electrode 4 in the finishing process and the lower limit of the minimum required amount of jump return common to each process are input. It is set in the quantity setting unit 12. During the electric discharge machining, the execution value calculation unit 13 calculates the execution value of the jump return amount based on the storage data of the machining conditions and the setting data of the jump return amount, and the feed mechanism control unit 14 according to the calculation result. The feed mechanism 5 of the electrode 4 is controlled.

In calculating the execution value, for example, the following equation can be used. Je = Js- (Gc-Gf) Formula 1 Here, Je is the execution value of the jump return amount, Js is the set value of the jump return amount, Gc is the machining clearance of the current process,
Gf is the processing clearance in the final step.

FIG. 2 is a flowchart showing the processing contents of the execution value calculation unit 13. In each step, the operation unit 13 reads the set value (Js) and the lower limit value of the jump return amount from the jump return amount setting unit 12, and also reads the processing clearance (Gc) of the current step and the processing of the final step from the processing condition storage unit 11. The clearance (Gf) is read, and the execution value (Je) of the jump return amount is calculated using the above equation (1).
When the execution value is smaller than the lower limit, the execution value is corrected to be equal to the lower limit.

Therefore, according to the electric discharge machining method of this embodiment, the amount of jump return of the electrode 4 during machining is changed in accordance with machining conditions in the process, that is, machining clearance. Since the machining clearance is set to be larger for rough machining and smaller for finish machining, as shown in FIG. 3, during actual electric discharge machining, the electrode 4 jumps at the lower limit or a return amount close to the lower limit in the rough machining start step. As the process proceeds from the rough machining to the finishing machining, the jump is performed with a larger return amount, and in the final process of the finishing machining, the jump is performed with the returning amount of the set value.
Therefore, in roughing, waste time without processing is omitted,
The machining time can be greatly reduced, and the machining can be maintained in a stable state without causing a concentrated discharge in the finish machining.

FIG. 4 illustrates a comparison result of machining time between the electric discharge machining method of the present invention and the prior art. The working mode is such that the workpiece is steel, the electrode is copper of φ30, and the swing radius is 0.25.
mm, processing depth 10mm, final finished surface roughness 6μmR
max, and the jump return amount is 3 for both the present invention and the related art.
The lower limit was set to 5 μm. As is evident here, according to the method of the present invention, the processing time can be shortened by several tens of percent compared with the conventional method, especially in the rough processing.

FIG. 5 shows another embodiment of the electric discharge machine according to the present invention. This electric discharge machining apparatus includes a storage table 16 that stores machining conditions and an optimum value of the amount of jump return for each process in a correlated manner, and the feed mechanism control unit 14 controls the feed mechanism 5 according to the stored data. The electrode 4 is configured to jump with a larger return amount as the process proceeds from the rough processing to the finishing processing.

In the above embodiment, the processing clearance is used as the processing condition. However, for example, the processing current is large in the rough processing and small in the finishing processing. Alternatively, the execution value of the jump return amount may be calculated so as to increase in the finishing processing. In addition, the configuration of each unit may be appropriately changed and embodied without departing from the spirit of the present invention.

[0015]

As described above in detail, according to the electric discharge machining method and apparatus of the present invention, as the process progresses from rough machining to finish machining, the electrode jumps with a large return amount, so that the dead time is reduced in the rough machining. It can save processing time by omitting it,
In the finishing machining, there is an excellent effect that machining can be stably maintained without generating concentrated discharge.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of an electric discharge machine according to the present invention.

FIG. 2 is a flowchart showing processing contents of an execution value calculation unit in FIG. 1;

FIG. 3 is a characteristic diagram showing an actual jump return amount by the electric discharge machining method of the present invention.

FIG. 4 is a table illustrating comparison results of processing times according to the present invention and a conventional method.

FIG. 5 is a schematic view showing another embodiment of the electric discharge machine according to the present invention.

[Explanation of symbols]

1. Processing tank, 2. Table, 3. Work, 4.
Electrode, 5 ··· Feed mechanism, 11 ·· Processing condition storage unit, 12
..Jump return amount storage unit, 13 ... Execution value calculation unit, 1
4 ··· Feed mechanism control unit, 16 ·· Storage table.

Claims (3)

[Claims] In an electric discharge machining method for machining a workpiece while jumping an electrode, an amount of jump return of the electrode is changed according to machining conditions, and the greater the amount of the electrode jumps as the process progresses from rough machining to finish machining. An electric discharge machining method characterized by performing the following. 2. An electric discharge machining apparatus for machining a workpiece while jumping an electrode, means for storing machining conditions for each process, means for setting a return amount of the electrode and its lower limit, storage data and setting data. Means for calculating the execution value of the jump return amount based on the calculation result, and means for controlling the feed mechanism of the electrode according to the calculation result. The feature is that the electrode jumps with a larger return amount as the process proceeds from rough processing to finish processing. Electrical discharge machining equipment. 3. An electric discharge machining apparatus for machining a workpiece while jumping an electrode, means for correlating and storing machining conditions and an optimum value of a jump return amount for each process, and controlling an electrode feed mechanism according to the stored data. An electric discharge machining apparatus, comprising: means for jumping the electrode by a large return amount as the process progresses from rough machining to finish machining.