JPS5946731B2 - Electric processing equipment - Google Patents

Description

Detailed Description of the Invention The present invention involves making an electrode and a workpiece face each other with a small machining gap as in electric discharge machining or electrolytic machining, and injecting a machining fluid such as an insulating liquid or an electrolyte into this gap. The present invention relates to an energization processing device that supplies electricity and processes the workpiece by passing current between the electrode and the workpiece.

Conventionally known devices of this type perform machining by moving the electrode and the workpiece toward or away from each other in a single axis, but in this case, the relative positions of the electrode and the workpiece are electrically controlled. For example, when the clearance between the male and female molds is 0.1 to 2, as in a drawing mold, etc.
If it also becomes wlB, make male and female types separately, or
As shown in Fig. 1, the workpiece 2 and the electrode 1 can be moved relative to each other perpendicularly or parallel to the Z-axis direction (arrow Z) in which the electrode 1 is fed to machine the workpiece 2. A method of obtaining clearance has been proposed. That is, by moving the outer circumference 3 of the electrode 1, the inner circumference 4 of the workpiece 2 corresponding to the outer circumference 3 is moved.
In order to process the workpiece, the outer circumference 3 is first moved from position Po to P and brought into contact with the inner circumference 4 of the workpiece 2. At this time, the external points A, B, and C on the electrode 1 also move by the displacement vector corresponding to P4 from Po. Next, each point A, B, C,
By rotating with a radius equal to the vector dl around its original position, the clearance between the electrode 1 and the workpiece 2 in a plane perpendicular or parallel to the z-axis is all equal to the length of the vector dl. Become. If the same operation is repeated at each position, all surfaces of electrode 1 facing workpiece 2 will be processed at the same distance. It is recognized for its characteristics of extremely high processing accuracy and excellent productivity, taking advantage of the features of processing. By the way, in general, in electrical machining, in order to remove the workpiece powder or electrolytic sludge generated between the electrodes, the machining fluid is applied to the electrode or the workpiece in advance by liquefying H, H2, H3, etc., as shown in Figure 2. - is opened, and the pump 6 injects or suctions from the tank 5 through the squeeze valve □, and depending on the shape of the workpiece, a large number of liquefied liquids are opened.

However, in the above-mentioned processing method in which the relative positions of the electrode and the workpiece are constantly changing, depending on the relative positions of the electrode and the workpiece, the liquids of each liquefied H4, H2, H3, etc. A phenomenon occurs in which the amount becomes the maximum in the non-machined gap G1 and the minimum in the machining gap G2, which causes a problem in the machining content. In other words, the machining gap G2 generates the largest amount of machining powder and has a large amount of liquid, which is critical, but the opposite phenomenon occurs, and it has the major drawback of generating arcs and reducing machining speed. It was hot. The present invention has been made in view of the above points, and the machining electrode and the workpiece are opposed to each other through a machining gap, and the machining electrode and the workpiece are given relative motion to partially close the machining gap. In an electrical processing device that performs processing in a processing gap narrowed to
Machining is performed by ensuring the flow rate of machining fluid in the machining gap, and the fluid pressure is detected for each of the multiple fluid holes to determine the gap length, and the fluid flow rate is optimized and controlled, thereby preventing insufficient fluid volume. An object of the present invention is to provide an electrical machining device which prevents abnormal arcing caused by such a problem and a decrease in machining speed that accompanies it, and also prevents abnormal consumption caused by an excessive increase in hydraulic pressure.

An embodiment of the present invention shown in FIG. 3 will be described below.

In FIG. 3, 1 is an electrode and 2 is a workpiece. The gap length between the electrode 1 and the workpiece 2 in the Z-axis direction is determined by a hydraulic cylinder 8 and a servo valve 9 that controls the oil amount. It is controlled by a hydraulic servo mechanism. The workpiece 2 is placed on an X-Y cross table 10, and the cross table 10 is connected to drive motors 13x, 13y via ball screws 11X, 11y and gearboxes 12x, 12y connected thereto. Inside Z
Machining can be performed while changing the relative position with respect to the workpiece 2 even in directions other than the axial direction. A processing power source 14 is connected to the electrode 1 and the workpiece 2, which includes a DC power source 15, a switching element 16 connected in series, a current limiting resistor 17, and a power source for controlling pulse generation. The oscillation circuit 18 can supply an intermittent pulsed current between the electrode 1 and the workpiece 2 (hereinafter referred to as the gap), so that the electrode 1 can process the workpiece 2. The hydraulic servo mechanism can determine the state of the electrodes, such as short circuit, normal discharge, and other phenomena by detecting the voltage V between the electrodes. When the inter-electrode impedance decreases, the inter-electrode gap is opened, and if normal, the inter-electrode gap is stopped, and when the inter-electrode impedance is open, the inter-electrode gap is closed. Further, the position detection element 20 attached to the main shaft 19 detects the electrode position on the Z axis, and furthermore, the Z axis is detected by analog calculation with the extreme state detection output Es.
A circuit 21 for servoing in the axial direction is provided, and
The relative position of the electrode and the workpiece is controlled by a position control device 22 in relation to the movement in the Y plane. Generally, the position control device 22 uses a numerical control device, a tracing control device, or the like. The tank 23 is filled with machining fluid 24, and there are always fluid holes H in the machining gaps Gl, G2, and G3.
Processing liquid is supplied through 1, H2, H3, and so on. A liquid flow rate control element E is provided between each liquid hole and the pump 6.
l. E2, E3... are inserted, and each liquid flow rate control element ElE2, E3 has a flow rate limiting resistor Rl, R, respectively.
2, R3... are connected in parallel. Further, each element El, E2, E3 is controlled by a flow rate control circuit 25. Furthermore, the hydraulic pressure in each hole is measured by hydraulic pressure detection elements Kl, K2, K3, and the signals are transmitted to the flow rate control circuit 25. Here, the liquid flow rate control circuit 25 will be explained using FIG. 4.

In FIG. 4, E2 and E3 are voltages corresponding to a certain hydraulic pressure value, and by comparing these voltages with the output voltage of the hydraulic pressure detection element K by comparators 26 and 27, the output of the comparator 26 becomes E3. Corresponding hydraulic pressure, e.g. 0.1
When the output of K is greater than kg/Cd, it is output as logic level 21', and the output of 27 is equivalent to E2, for example 0.01 kg/
Similarly, when the output of K is greater than Cd, it is output as 12. These outputs are AND gates 28, 29 and NNO
The signal is logically determined by the T element 30 and the 0R gate 31, and is inputted to the amplifier 33 that drives the liquid flow rate control element E1 through the delay circuit 32, and is also connected to the logic circuit composed of 28, 29, 30, and 31. Although not shown, the liquid pressure detection elements K2 and K3 and the liquid flow rate control element E
A circuit similar to that described above is also connected between E2 and E3. In such a circuit configuration, the flow rate limiting resistors Rl, R2, R
The reference voltage E3 for low fluid pressure detection determines whether the gap between the poles at each fluid hole position is wide or narrow due to the flow of machining fluid only by E3.
If the gap between the electrodes is narrow, the liquid flow rate control element E is driven. If the area is wide, it is assumed that liquid supply is not necessary and the current state is maintained. After the carrier liquid flow rate control element E has been operated, it is determined whether to continue or stop driving the liquid flow rate control element E by comparing it with a reference voltage E2 for detecting an appropriate pressure. That is, when the gap between the poles becomes wider, the liquid flow rate control element E
Stops driving. At this time, since it takes some time for the liquid pressure to reach a steady value when the liquid flow rate control element E is turned on and off, a delay circuit 32 is provided. As the liquid flow rate control element E, a constant flow rate valve is used so that an appropriate amount of machining liquid is constantly supplied to the gap between the poles where machining is to be performed, regardless of the hydraulic pressure. Also, a method of simply using constant flow rate characteristics elements as the liquid flow rate control elements El, E2, and E3 without providing a special control circuit 25 has the same effect, but the liquid does not flow even in an open gap where there is no need for liquid supply. Since the liquid flows, the flow of this liquid may interfere with the gap during machining, making machining unstable.

However, it is sufficiently effective and suitable as a method that can be easily implemented. As stated above, according to this invention,
The machining electrode and the workpiece are opposed to each other through a machining gap, and relative motion is applied to the machining electrode and the workpiece to partially narrow the machining gap and machining is performed in the machining gap. and supplying machining fluid to the machining gap from a plurality of machining fluid supply holes provided in at least one of the machining electrode and the workpiece, and passing the machining fluid between the machining electrode and the workpiece. In machines that perform machining while being energized, a fluid pressure detection element detects the fluid pressure in the machining fluid supply hole for each of the plurality of machining fluid supply holes, and a fluid pressure detection element detects the fluid pressure in the machining fluid supply hole, and the fluid A liquid flow rate control element is provided to control the amount of machining fluid in the machining fluid supply hole so that the amount of machining fluid increases when the pressure increases and decreases when the fluid pressure decreases. The amount of machining fluid supplied at the point where the machining fluid is being processed or has reached the appropriate gap is kept constant so that the flow rate remains constant even if the fluid pressure in the gap changes due to changes in the gap length. In the gaps where no electrical discharge can occur, the flow rate is kept extremely low to prevent excess machining fluid from being supplied and to ensure that machining is possible at any time. Even if the condition occurs, it can be detected immediately, so that an appropriate machining fluid is always supplied to the machining gap. The above explanation has been given using electric discharge machining as an example, but the same applies to electrolytic machining, because if gas is mixed into the machining fluid, almost only gas will be blown out in a wide gap. , the apparent resistivity increases, almost no machining is done, and therefore no integral effect occurs, making it possible to achieve extremely high accuracy. It has the advantage of producing a uniform surface over the whole area. Furthermore, even if the electrode area is large, the corresponding area during actual machining is small, so even with a small capacity machining power source, the current density on the machining surface can be high. In addition, the large current density leads to a narrow electrolytic gap, which is expected to improve the shape consistency of the electrode. As described above, according to this invention,
Since machining fluid suitable for the machining gap length is supplied, abnormal arcing due to insufficient fluid volume and the associated decrease in machining speed are prevented, and abnormal erosion due to excessive increase in fluid pressure is eliminated, among other effects.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the principle of clearance machining, Fig. 2 is a sectional view showing the main parts of a conventional electrical processing device, Fig. 3 is a configuration diagram showing an embodiment of the present invention, and Fig. 4 is the above FIG. 4 is a circuit diagram showing one embodiment of the liquid flow rate control circuit shown in FIG. 3; In the figure, Kl, K2, K3 are hydraulic pressure detection elements, Rl,
R2 and R3 are flow rate limiting resistors, El, E2 and E3 are liquid flow rate control elements, 6 is a pump, and 25 is a flow rate control circuit.

Claims (1)

[Claims] 1. Electrical machining in which a machining electrode and a workpiece are opposed to each other through a machining gap, a relative movement is given to the machining electrode and the workpiece, the machining gap is partially narrowed, and machining is performed in the machining gap. and supplying machining fluid to the machining gap from a plurality of machining fluid supply holes provided in at least one of the machining electrode and the workpiece, and passing the machining fluid between the machining electrode and the workpiece. A hydraulic pressure detection element for detecting the hydraulic pressure of the machining fluid supply hole for each of the plurality of machining fluid supply holes, and according to an output signal of the fluid pressure detection element, It is characterized by the provision of a liquid flow rate control element that controls the amount of machining fluid in the machining fluid supply hole so that the amount of machining fluid is increased when the fluid pressure increases, and is decreased when the fluid pressure decreases. Electrical processing equipment.