JPS632613A - Electric discahrge machining method and attachment thereof - Google Patents

Abstract

PURPOSE:To keep a swarf quantity below the level at all times as well as to aim at stabilization in a machining state and reduction in the discharge time, by installing a swarf quantity detecting function detecting the worsening of the machining state in a workpiece, and making an electrode's jump condition so as to be varied at the time of accumulation of the swarf quantity being more than the specified level. CONSTITUTION:A difference (memory 3) between a position (memory 1) where an electrode at the time of its jump motion performed lately and the deepest position (memory 2) where it goes down till leading to its latest jump motion is found. Next, the product 4 of a difference X between this difference (memory 3) and swarf quantity optimum value (memory 6) and a difference between swarf quantity counting time and a preceding counting time is found. In addition, integral critical value (memory 7) is set, comparing time integral value (memory 8) until the latest counting time of the said X with the integral value (memory 7) by a comparator 5, and the jump condition is altered when the time integral valve (memory 8) is equal to the integral critical value (memory 7). Thus, the swarf quantity between electrodes is always kept to less than the reference level and a machining state is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric discharge machining method and an apparatus therefor.

[Conventional technology] Conventionally, processing powder such as metal processing powder and decomposition products of processing fluid generated between the machining electrodes during electric discharge machining is usually treated by pumping due to the explosive pressure generated by machining, forced circulation of the processing fluid, and jumping movement of the electrode. As a result of this action, it is removed from the machining gap and the machining condition is restored. The jump motion of the electrode is normally at regular intervals, and the period and jump amount are variable and can be set by the user based on the machining area, depth, etc.

[Problems to be solved by the invention] Conventional electric discharge machining is performed as described above, and the electrode jump conditions are only set by the user, so the set values are dependent on the workpiece, machining depth, or machining depth. It is very difficult to find appropriate setting values because it depends on the conditions and the machining speed may vary depending on the setting method, or arcing may occur.

This invention was made in order to solve the above-mentioned problems, and it determines whether the machining condition of the workpiece is good or bad, and when deterioration of the machining condition is detected, it changes the machining conditions by changing the machining conditions. The object of the present invention is to obtain an electric discharge machining method and an apparatus therefor capable of stabilizing the electric discharge machining process.

[Means for Solving the Problems] In this invention, in an apparatus in which a workpiece is electrically discharge-machined in a machining fluid using electrical discharge energy with an electrode, the position △n where the electrode has descended during a recently performed jump The difference between △n−■k=ε
Find n, then calculate the difference between this εn and the optimum processed powder amount α,
Find MX of the difference between the processed powder amount measurement time tn and the previous measurement time kn-1, and further set the integral limit value β to calculate the sum of the above X up to the latest measurement time tn, that is, the time integral value Σ up to tn. (where α≦Σ≦β) is determined, and this time integral value Σ is compared with the integral limit value β, and when Σ is equal to β, the jump condition is changed.

In addition, the device of the present invention includes (a) a memory in which the position △n where the electrode descended during the most recently performed jump movement is recorded; , a memory in which the deepest position aj at which the electrode has descended is recorded (however, during the first jump movement, the position at which the electrode has descended is the deepest position, that is, 1 = Δl), and (c) the above-mentioned electrode descending position Δn and a memory in which the difference △n-1h k=εn is recorded between
(e) A memory in which the processed powder amount optimum value α is recorded; and (e) a memory in which the processed powder amount measurement time kn-1 is recorded.

(f,) The above processed powder amount measurement time tn and the previous measurement time kn
-1, a memory in which the result x of the difference between εn in the above-mentioned (c) term and the above-mentioned optimum processed powder amount α is recorded, (g) a memory in which the 711 minute limit value β is recorded, and (h ) A memory for recording the sum of X in the above Cf) term up to the most recent measurement time tn, that is, the time integral value Σ up to tn (however, α≦Σ≦β); (i) calculating the above εn + X *Σ; and calculation means that can be used.

Compare the integral limit value β on the above time integral value on the CD, and Σ is β
and a comparison means for conveying information if .

[Function] According to the present invention, when the amount of processed powder between the machining electrodes accumulates above a certain level, the jump conditions of the electrodes are changed, thereby making it possible to always maintain the amount of processed powder between the machining electrodes at a level below the reference level.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a block diagram of the electrical discharge machining device, Figure 2 is a flowchart for one jump movement of the electrode, Figures 3 and 4 are graphs for the jump operation principle and jump movement, and Figure 5 is a diagram of contamination. It is a graph showing the relationship between the amount and the contamination m value. In Figure 1, (12) is the processing J
fi(13) indicates the workpiece, and (14) indicates the workpiece (
12) shows an electrode for electrical discharge machining. Now, at the start of machining the workpiece, memories (1) to (3) are cleared to zero. When machining is started and the first electrode jump movement is performed according to the user settings, the machining electrode Δ1 at the end of the jump movement is stored in memory (1) and deepest position recording memory (2).
). From the second time onwards, the electrode position △n at the end of the most recent jump is always recorded in memory (1), and at the same time,
The deepest position of the electrode at the end of the jump movement performed in the past
Xk is compared by a comparator (5), and if Δn is equal to λ, the electrode position Δn is regarded as the deepest position and recorded in the memory (2).

In cases other than the above, the computing unit (4) calculates the difference Y between the electrode position Δn and the deepest position λ and records it in the memory (3). That is, the amount of contamination Yn (the amount by which the electrode has retreated from the deepest position by the servo) at the end of the most recently performed jump movement is always recorded in the memory (3). On the other hand, the optimum contamination value α is input to the memory (6), and the contamination limit value β for the contamination a, which is a condition for changing the jump condition, is input to the memory (7). Furthermore, the memory (9) records the most recent contamination amount measurement time tn, and the memory (10) records the previous measurement time tn. and kn-1, and the difference between the amount of contamination and the optimum value, that is, Kn=(tn tn-+)(Yn-α), and record them in the memory (11). The memory (8) stores the sum of KO''Kn-1 up to the previous point in time, that is, the contamination integral value, Σ=Ko+K++K2+-Kn-+=(
t+ to)(Y+-α) + (tz-t+)(
Yz-α)+...+(jn-1-tn-2) (Yn
−+ −α) is recorded, to which Kn is added by the arithmetic unit (4). However, if the value of the integral value Σ exceeds the limit value β by the comparator, then Σ = β, and if it is less than the optimal value α, then Σ = α, and the integral value Σ changes from α to β.
shall not exceed the scope of This is to quickly and appropriately detect unstable conditions in machining. The yi minute value Σ is recorded again in the memory (8). Further, when the integral value Σ is equal to the limit value β, that is, when the contamination planting value Σ calculated by the calculator (4) is greater than β, the jump conditions are changed. This state corresponds to the point A in Fig. 3. This is the case, and it is thought that a large amount of processed powder was accumulated between the electrodes 8i and 8i. It is clear that if this state is left as it is, the processing speed will drop significantly as shown in FIG. However, point A shown in Fig. 4 is the same point as point A shown in Fig. 3. Changing the jump conditions means changing the jump conditions set by the user to jump conditions that further improve the processed powder discharge effect. For example, a jump where the jump interval is shortened to 4 stations and the jump amount is doubled is
etc. In FIG. 5, sections C and D are cases in which jumps are changed.

Regarding the timing of measuring the amount of contamination, the method for determining the amount of processed powder, the number of memories to be used, the jump conditions at the time of change, the configuration of the logic circuit, etc. shown in the above embodiment, those widely known within the scope of this invention are used. Modifications may be made freely, and the present invention encompasses all of these modifications. Further, in the embodiment, the explanation has been given of changing the jump conditions in order to keep the machining condition constant, but the same effect can be obtained by lengthening the pause time in the machining conditions. In other words, by extending the pause time in the machining conditions and lowering the machining current, the amount of machining powder produced can be reduced and the condition between the machining holes can be restored.

[Effects of the Invention] As explained above, according to the present invention, the amount of processed powder between the machining holes is always kept below the standard level because it is equipped with a processing powder amount detection function that detects the deterioration of the processing condition of the workpiece. This stabilizes the machining state, shortens the discharge time, and allows the user to efficiently set jump conditions.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an electric discharge machining apparatus according to an embodiment of the present invention, Fig. 2 is a flowchart showing the flow for one jump movement, and Figs. 3 and 4 are explanations of the operating principle and electrode jump movement. FIG. 5 is a graph showing the relationship between the amount of contamination and the integral value of contamination. In the figure, (1) to (3) are memories, (4) is an arithmetic unit, (5) is a comparator, (6) to (11) are memories, and (12) is a comparator.
) is the workpiece, (14) is the electrode. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Masuo Oiwa Figure 1, Figure 14; Figure 2, Figure 3, Figure 4 □Lingyan

Claims (2)

[Claims] (1) In electrical discharge machining of a workpiece in machining fluid using electrical discharge energy with an electrode, the position △_n where the electrode descended during the most recent jump motion and the most recent jap motion Difference from the deepest position ■_k where the electrode descends during the jump movement of △_n - ■_k = ε_n
Next, calculate the difference between this ε_n and the optimum processed powder amount α,
Processed powder amount measurement time t_n and previous measurement time t_n_-_1
Find the product X with the difference between An electric discharge machining method characterized in that a time integral value Σ and an integral limit value β are compared, and jump conditions are changed when Σ is equal to β. (2) In an apparatus for electric discharge machining of a workpiece in a machining fluid using electric discharge energy between an electrode and b) In the jap movement up to the recent jump movement,
A memory in which the deepest position ■_k at which the electrode descended is recorded (however, during the first jump movement, the position at which the electrode descended is the deepest position, that is, ■_1 = △_1), and (c) the above electrode descending position △ A memory in which the difference △_n−■_k=ε_n between _n and the deepest position ■ above is recorded, and (d
) a memory in which the optimum processed powder amount α is recorded; (e) a memory in which the processed powder amount measurement time t_n_-_1 is recorded; and (f) the above processed powder amount measurement time and the previous measurement time t_n.
(g) A memory in which the integral limit value β is recorded, (h ) A memory for recording the sum of X in item (f) above up to the most recent measurement time t_n, that is, the time integral value Σ up to t_n (however, α≦Σ≦β); (i) calculating the above ε_n, X, and Σ; (j) Comparison means for comparing the time integral value Σ and the integral limit value β and transmitting information when Σ is equal to β.